B3277GS Pressure Washer Pumps by Generac

Familiarization & Troubleshooting GuidePRESSURE WASHER

BRIGGS & STRATTON CORPORATIONMilwaukee, WI 53201

Part No. B3277GS Rev. 0 11/98Printed in U.S.A.

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This guide has been written and published by Briggs & Stratton Corporation to aid our dealers' mechanics andcompany service personnel when servicing the products described herein.

It is assumed that these personnel are familiar with the servicing procedures for these products, or like or similarproducts, manufactured by Briggs & Stratton Corporation. It is also assumed that they have been trained in therecommended servicing procedures for these products, which includes the use of mechanics hand tools and anyspecial tools that might be required.

Proper service and repair is important to the safe, economical and reliable operation of all engine driven systems.The troubleshooting, testing, service and repair procedures described in this guide are effective methods ofperforming such operations.

We could not possibly know of and advise the service trade of all conceivable procedures or methods by which aservice might be performed, nor of any possible hazards and/or results of each procedure or method. We havenot undertaken any such wide evaluation. Therefore, anyone who uses a procedure or method not described bythe manufacturer must first satisfy himself that neither his safety, nor the safety of the product, will beendangered by the service or operating procedure selected.

All information, illustrations, and specifications contained in this guide are based on the latest productioninformation available at the time of publication. However, Briggs & Stratton Corporation reserves the right tochange, alter, or otherwise improve the product at any time without prior notice.

Some components or assemblies of the product described in this guide may not be considered repairable.Disassembly, repair and reassembly of such components may not be included in this guide.

Copyright 2003 Briggs & Stratton Corporation

All rights reserved.

No part of this material may be reproduced or transmitted, in any form or by any means, electronic ormechanical, including photocopying, recording or by any information storage and retrieval system, without priorpermission in writing from Briggs & Stratton Corporation.

11 Operation 5

2 Pressure Washer Components 7Power Source 7

Pressure washer pumps 7

Inlet and Outlet Check Valves 8

Unloader - Pressure Regulator 8

Thermal Bypass System 9

Chemical Injection 9

Easy Start Valve 10

High Pressure Hose 11

Spray Guns 11

Spray Wands and Nozzles 12

3 General Information 13

Part 1 - General Maintenance 13

Chemical Injection System 13

Inlet Water Supply Connector 13

Inlet Supply Filter/Strainer 13

Hose, Spray Gun and Wand Systems 13

Spray Nozzle Servicing 14

Part 2 - Lubrication 15

Check Pump Oil Level 15

Change Pump Oil 15

Part 3 - Storage 16

Pump Storage 16

Protection Against Freezing 16

Purging Air From the System 16

4 Small Frame Electric Pump 17

Part 1 - Specifications and Views 17

Performance Specifications 17

Cross-Sectional View 18

Exploded View 20

Part 2 - Disassembly 22

General Information & Special Tools 22

Pump Head 22

Piston Housing Removal 23

Piston Housing Disassembly 24


Auto Start Switch Assembly 25

Axial Cam 26

Part 3 - Inspection 27

Seals, O-Rings, and Gaskets 27

Piston & Spring Assemblies 27

Pump Head and Piston Housing 27

Axial Cam Drive Components 28

Part 4 - Reassembly 29

Pump Head Assembly 29

Auto Start Switch Assembly 29

Chemical Inject Assembly 30

Piston Housing Assembly 31

Pilot Spacer Installation 31

Pump Head Bolts 32

Assemble Axial Cam 32

Oil Fill 32

Main Component Assembly 32

Final Assembly and Test 33

Part 5 - Troubleshooting 34

TABLE OF CONTENTS

Table of Contents

Portable Pressure Washer Familiarization and Troubleshooting Guide

Small Frame Gas Pump 35



Cross-Sectional view 36

Exploded View 38



Pump Head 40

Piston & Unloader Housing Removal 40

Piston & Unloader Housing Disassembly 41


Unloader 42

Engine Adapter 43




Engine Adapter, Pump Head and Piston/Unloader Housing 44



Engine Adapter 45

Unloader Assembly 45

Chemical Injection Assembly 45

Piston & Unloader Housing Assembly 46



Pilot Spacer Installation 48

Pump Head Bolts 49

Oil Fill 49


5 Medium Frame Pump 51




Exploded View 55



Pump Head 56


Pistons and Piston Springs 57

Pump Head 58

Spacer Plate 58

Inlet Check Valves 59

Outlet Check Valves 59

Unloader Spindle Assembly 59


Thermal Bypass Actuator Removal 60



Seals 61

Check Valves 61

Head Gasket 61

Engine Adapter O-Rings 62

Engine Adapter, Pump Crankcase and Spacer Plate/Head 62



High Pressure Outlet/Chemical Injection Assembly 63


Engine Adapter 64

Piston Oil Seals and Pistons 65

Spacer Plate 67

High Pressure Seal Assembly 67

Check Valve Assembly 68

High Pressure Outlet and Chemical Injection Assembly 69

Unloader Spindle Assembly 69

Pump Head Installation 70


Oil Fill 72


2

Table of Contents


TABLE OF CONTENTS

36 Large Frame Pump 75




Exploded View 78



Pump Head 80

Axial Cam Drive Components(Tapered Engine Shaft) 81

Axial Cam Drive Component (Straight Engine Shaft) 82

Pistons and Piston Springs 82

Regulator/Unloader Valve 82

Cylinder Head 84

Thermal Bypass Actuator Removal 85

Spacer Plate 86



Oil Seals 87

Inlet Check Valve Seals 87

Outlet Check Valve Seals 87

Head Gasket 88

Engine Adapter Gasket 88

Engine Adapter, Pump Crankcase, Spacer Plate and Head 88



Unloader-Pressure Regulator Valve 90


Engine Adapter 91

Piston Oil Seals and Pistons 94

Spacer Plate 96


Pump Head Installation 98

Unloader-Pressure Regulator Valve 99


Oil Fill 101


Glossary 105

TABLE OF CONTENTS

Table of Contents


4Table of Contents


5Operation of a pressure washer system may be brieflydescribed as follows. Please refer to Figure 1.1 for visualcomponent identification:

1. An inlet hose delivers water to the motor-driven, piston-type pump. An inlet strainer (item 6) protects the pump(item 5) against damage from solid impurities. The motordriving the pump (item 9) may be gas or electric.

2. Rotary motion of the motor crankshaft is converted toreciprocating motion of the pumps pistons using an axialcam.

On a pistons suction stroke, an inlet valve opens andwater is drawn into the piston chamber. On the pistonspressure stroke, that pistons inlet check valve closes andits outlet check valve is forced open so pressurized watercan leave the chamber. There is one inlet check valve andone outlet check valve for each piston.

PRESSURE WASHER OPERATION

Section 1 Operation

Pressure Washer Familiarization and Troubleshooting Guide

Item Name1 Spray nozzle2 Hi-Lo nozzle collar3 Spray gun extension wand4 Spray gun with locking trigger5 Pump, including optional thermal relief and/or

easy start valve

Item Name6 Inlet strainer7 Unloader/pressure regulator valve8 Chemical inject fitting (optional)9 Engine on cart

10 High pressure hose

Figure 1.1 Example Pressure Washer System

63. The linear movement of the pistons pump a fixed volumeof water through the pressure washer system. Thevolume of water flow depends on

a. piston diameter

b. length of piston stroke

c. number of pistons

d. number of piston strokes per minute.

4. The pressure that builds up in the system then dependson the size of the spray nozzle orifice (item 1).

5. The fixed volume of water flows past anunloader/pressure regulator valve (item 7), an optionalchemical injection assembly (item 8), through a high-pressure hose (item 10), and to a spray gun (item 4).

6. The spray gun permits the operator to turn the flow ofwater on or off.

7. If the water flow is turned off, water pressure within thepump will increase until the unloader/regulator valve (item 7) is moved off its seat. Flow is then bypassed backto the pump inlet through an internal bypass channel.Fluid bypass continues as long as the spray is turned off.

8. Recirculating bypass water can become hot enough todamage seals and other pump parts. Some pressurewasher systems may be equipped with an internal thermalrelief valve which automatically replaces hot water withcool water.

9. The optional chemical injection assembly (item 8) permitsdetergents or other chemicals to be drawn into the waterstream and (along with the water) discharged from thenozzle.

10. The nozzle collar (item 2), a part of the spray gunnozzle, permits easy selection of high or low velocityspray or a fan or stream spray pattern.

11. An optional easy start valve relieves pump outletpressure during cranking for quicker and easier starts.

12. As a nozzle is used, it often becomes clogged withvarious types of matter. A clogged nozzle obstructs thewater flow causing a reduction in outlet pressure. It alsomay cause the water stream to pulsate while the gun istriggered. Therefore, the nozzle should be checked andcleaned before every use, using the cleaning kit providedwith every Generac Portable Productspressure washer system.

13. The flow of water through the nozzle will gradually wearaway the nozzle orifice, causing the orifice to becomelarger. This enlargement will eventually cause a reductionin system pressure. For this reason, the nozzle should bereplaced periodically and always replaced with thecorrect nozzle.

Section 1 Operation


7Power SourceGenerac Portable Products uses severalengine manufacturers and different pump types on itspressure washers. Generac Portable Productsalso uses an electric motor on some models.

The motor horsepower rating is designed into the overallrating of the pressure washer. Pressure pumps require aspecified amount of horsepower for the pressure rating ofthe pump. It is important to remember that engineperformance may be miss-diagnosed as a failed pump, and afailed pump may also be miss-diagnosed as a faulty engine.

This manual does not cover service and repair of the engine.Refer to the engine manufacturers service manual for enginerepair specifications.

Pressure washer pumpsGenerac Portable Products pressure washerpumps are positive displacement, piston type pumps. Theyuse an axial cam to impart a reciprocating motion to itsthree (3) pistons. The volume of water moved by the pumpdepends on:

1. The axial distance each piston moves on its pressurestroke

2. The diameter of each piston bore

3. The rotating speed of the axial cam (RPM of the engine orelectric motor)

4. The number of pistons

Theoretically, a pump will always move the same volume ofwater, regardless of flow restrictions.

The pumps axial cam is coupled to the engine crankshaft, sothat it revolves at the same speed as the engine. Figure 2.1depicts a simplified cross-sectional diagram of a typicalpressure washer pump mechanism.

If the pump simply discharges water to atmosphere, nopressure will be created. A pressure buildup in the systemoccurs when flow is restricted downstream from the pump.By adding a nozzle to the system, pressure will increase toforce the same volume of water through the nozzle orifice.The smaller the nozzle orifice, the greater the pressureneeded to force the pumped volume through the nozzle.

PRESSURE WASHER COMPONENTS

Section 2 Pressure Washer Components


Figure 2.1 Pressure Washer Pump

Item Name

1 Pressure adjust knob

2 Thermal bypass actuator

3 Inlet check valve

4 Garden hose connector/strainer

5 Thermal bypass outlet

6 Axial cam

7 Engine drive shaft

8 Engine adapter bearing assembly

9 Piston shoe bearing assembly

10 Piston spring retainer

11 Piston return spring

12 Piston

13 Outlet check valve

14 High pressure discharge port

8Inlet and Outlet Check ValvesA set of six (6) inlet and outlet check valves work inconjunction with the pump pistons to create volume flow.As a piston is moved toward the axial cam by its returnspring during its suction stroke, that pistons inlet checkvalve opens and allows water to enter the pumpingchamber. During the suction stroke, that pistons outletcheck valve is forced closed, as depicted in Figure 2.2.

When the piston is pressed forward by the axial cam on itspressure stroke, its inlet check valve is forced closed and itsoutlet check valve is forced open, as seen in Figure 2.3.

Unloader - Pressure RegulatorOutput water pressure can be adjusted using the pressureadjust knob on the Unloader-Pressure Regulator assembly.Turn the knob clockwise to increase pressure (up to therated maximum pump pressure), counterclockwise todecrease pressure.

The pressure washer is provided with an unloader -pressure regulator valve to protect the pump and hosesystem whenever water flow is blocked upstream. Blockageis caused when the spray gun trigger is normally closed orby a kinked pressure hose or a clogged nozzle. Without anunloader system, water pressure could increase until theengine stalls or part of the system ruptures to relieve thepressure.

As shown in Figure 2.4, the unloader valve will open at apreset maximum pressure to divert all or part of the flowback to the pump inlet. During such shutdown conditions,the water will circulate from the pumping chambers to thepump inlet and then back to the pumping chambers.



Figure 2.4 Typical Unloader - Pressure Regulator System

Figure 2.2 Inlet Check Valve - Suction Stroke

Figure 2.3 Outlet Check Valve - Pressure Stroke

Item Name

1 Inlet check valve

2 Outlet check valve

9Thermal Bypass SystemWhen the trigger on the gun is not squeezed, the water inthe pump is recirculating and under pressure. This conditioncauses the water in the pump to become hot. Excessivelyhot water may cause damage to the pressure washer pumpelements. To resolve this problem, someGenerac Portable Products pressure washersare equipped with a thermal bypass system. Figure 2.5depicts components of such a system.

At a water temperature of approximately 140F, the thermalactuator stem will push the thermal piston off its seat.Heated water will then bleed out of the pump to theground. As cool water enters the pump, the thermalactuator stem retracts and the thermal piston closes againstits seat, halting the water bleed-off.

Chemical InjectionGenerac Portable Products pressure washerscommonly incorporate a means of adding wax orcleaning/sanitizing chemicals into the low-pressure waterstream. As depicted in Figure 2.6, the chemical injectionassembly includes a venturi, a spring-loaded ball and seat, achemical siphon tube, and a strainer.

As low-pressure water flows through the injector venturithroat, its velocity increases and its pressure decreases. Thesuction created by the low pressure at the venturi throatdraws the liquid chemical through a strainer into the siphontube, around and past the spring-loaded ball, through smallorifices in the venturi, and into the water stream.

Chemical injection only operates at the low pressure settingbecause detergents and chemicals require some soak orresidence time on the surface to be cleaned. Low pressurealso avoids splashing, over-spraying, and waste.



Figure 2.5 Thermal Bypass System

Item Name

1 Thermal bypass actuator

2 Thermal bypass actuator stem

3 O-ring

4 Thermal bypass piston

5 Thermal bypass spring

Item Name

1 Venturi o-ring

2 Spring

3 Check ball moved OFF valve seat

4 Chemical injection fitting

5 Chemical injection venturi

6 Discharge port

7 Chemical solution reservoir

8 Siphon tube strainer

9 Chemical siphon tube

Figure 2.6 Low Pressure Suctionof Chemical InjectionSystem

10

When the pump is in the high pressure mode, the chemicalinjector ball is forced against its seat, cutting off the siphoneffect and preventing water from back-flowing into thechemical reservoir. Figure 2.7 depicts this high pressurecondition.

The chemical injector must be carefully sized for the system.Too small of a venturi orifice will result in too low apressure and too much chemical will flow into the stream.Too large an orifice will cause too much pressure at theventuri throat and the injector will not work.

Easy Start ValveCertain larger Generac Portable Productspressure washers may be equipped with an easy start valve.This patented device relieves pump outlet pressure duringengine cranking so that it is easier for an individual to pullthe recoil starter rope.

Figure 2.8 depicts a Generac PortableProducts medium frame pump in its starting condition.Inlet water is connected to the pumps garden hoseconnector. Air has been purged from the pumps waterpassages. The check ball is attached to its restraint magnet(magnet not shown).

In this condition, the pumps internal water pressure is atgarden hose pressure. Water is free to circulate throughoutthe pump without restriction, thus permitting an easier pullon the starter rope.

As soon as the engine starts, water flow forces the checkball against its seat, closing the garden hose pressure waterpassage. Pressure within the system becomes regulated bythe unloader valve setting and the nozzle restriction.



Item Name

1 Ball shown seated, cutting off chemicalflow

2 Chemical injection fitting

3 Siphon tube

4 Check ball seat

5 Venturi throat

Figure 2.8 Starting Condition

Item Name

1 Location of restraint magnet (not shown)

2 Check ball shown attached to magnet

3 Inlet water channel

Figure 2.7 High Pressure Cut-off of Chemical InjectionSystem

11

Bypass refers to the direction of fluid flow as the waterrecirculates through the pump. Bypass occurs when thenormal flow of water through a nozzle is shut off.

Figure 2.9 depicts the pump in the bypass condition with theengine running and the spray gun trigger released.

Figure 2.10 depicts the pump in a normal operatingcondition with the engine running and the spray gun triggerdepressed.

High Pressure HoseGenerac Portable Products uses excellentquality high pressure hoses appropriate for each pressurewasher model. Hose length, hose internal diameter, andhose pressure rating are all factored into the overall designof the pressure washer system.

Hose specification factors include: gallons per minute ratingof the pump, pressure rating of the pump, and pressuredrop over the length of the hose between the pump and thespray gun. Additional factors may also be used.

Accessory hoses are available to lengthen the hose from itsstock length. Generac Portable Products doesnot recommend exceeding a total length of 100 feetbetween pump and nozzle because excessive length mayadversely affect chemical injection and adequate highpressure operation.

Spray GunsGenerac Portable Products uses several typesof spray guns for different model pressure washers. Adiagram of a typical spray gun with the trigger closed is seenin Figure 2.11.



Figure 2.11 Typical Spray Gun Mechanism

Item Name

1 High pressure inlet connector

2 Spray gun body

3 Valve body

4 Valve return spring

5 Check ball

6 Check ball valve seat

7 Wand body

8 Trigger

9 Safety latch in lock position

Figure 2.10 Normal Operating Condition

Item Name

1 Outlet pressure water stream

2 Trapped line pressure piston shown in opencondition

3 Easy start check ball against its seat

4 Unloader spindle assembly


Figure 2.9 Bypass Condition

Item Name

1 Outlet pressure water stream

2 Trapped line pressure piston shown in closedcondition

3 Easy start check ball OFF its seat

4 Unloader piston assembly


12

Pulling back on the trigger moves the spray gun check balloff of its seat, as shown in Figure 2.12. The water then flowsthrough the open valve and out of the wand to the nozzle.

When the trigger is released, the valve shuts against its seatand the water flow is stopped. This condition causes thepump to enter the bypass mode.

CAUTION: Spray guns and wands are rated formaximum pressure and flow rate. Use of anincorrect spray gun and wand can be dangerous andwill adversely affect pump performance. Ifreplacement becomes necessary, you must replacethe gun as an assembly. Use only the spray gun andwand listed in the Repair Parts section of theowners manual for the specific pressure washermodel being serviced.

Spray Wands and NozzlesThe spray nozzle is critical to proper operation of apressure washer. The nozzle restricts the liquid flow andallows the required pressure to develop. The smaller thenozzle orifice, the higher the system pressure. Use of anozzle having too large an orifice will result in a reducedsystem pressure.

In addition to establishing system pressure, the nozzlebreaks the liquid into droplets, forms the spray pattern, andpropels the liquid in the proper direction.

Several different types of spray nozzles may be used. Themost popular type provides adjustable pressure and spraypatterns. For Generac Portable Productsnozzles, slide the nozzle backward for High Pressure spray;push the nozzle forward for Low Pressure spray; twist thenozzle clockwise for a Fan Spray Pattern; and twist thenozzle counterclockwise for a Narrow Stream.

In addition, Generac Portable Products offersseveral accessory nozzles, such as a rotating brush, utilitybrush, and turbo nozzle.

DANGER: Do not attempt to adjust pressure orspray pattern while spraying. Never place your handin front of the spray nozzle to adjust pressure orspray pattern.

Refer to the Owners Manual for the specific pressurewasher model for correct operating instructions.



Figure 2.12 Spray Gun - Trigger Open

13

Section 3 General Information


Part 1 - General MaintenanceThis section describes the general maintenance proceduresrecommended for pressure washer components that arecommon across product lines.

Chemical Injection System

Before each use, inspect the chemical injection suction hosestrainer. Clean as necessary, or replace if damaged, torn orperforated.

Examine the chemical suction hose and replace if damaged.

Rinse the chemical injection system thoroughly after eachuse by siphoning several pints of clean water through thesystem.

Inlet Water Supply Connector

The pressure washer may be equipped with a QuickDisconnect type connector for convenient attachment ofthe inlet water supply. This type of connector, depicted inFigure 3.1, operates easily if the o-ring is periodicallylubricated with a petroleum jelly.

The water supply quick-disconnect must be correctlyinstalled on the supply hose and the pressure washer or itsinlet supply filter will not be effective.

Inlet Supply Filter/Strainer

Remove the quick disconnect from the hose and inspect theinlet water strainer. It should be oriented so that thepointed part (the screen) points away from the pump(towards the garden hose).

A typical inlet supply connection is seen in Figure 3.2. Clean

the strainer or replace it if it is damaged, torn, orperforated. Reassemble the connectors, using petroleumjelly as necessary to ease the connections.

Hose, Spray Gun and Wand Systems

With the pressure washer OFF, inspect the hose connectionto the spray gun. Make sure it is tight. Test the trigger bysqueezing it and making sure it springs back to the OFFposition when released. Set the safety latch to ON and andtest the trigger, making sure the trigger cannot be squeezed.

With the pressure washer ON and the trigger latched OFF,verify the absence of leaks from the spray gun.

With the pressure washer OFF, inspect the high pressurehose for cuts, leaks, abrasions, bulging, kinking, or abuse.

With the pressure washer ON and the trigger latched OFF,verify the absence of leaks from the hose.

DANGER: Water spraying from a leaking hose caninject material into the skin or cause serious injury.Never attempt to repair high pressure hoses. Replacethe hose with a high quality hose that meets theminimum pressure rating recommended by themanufacturer.

An o-ring maintenance kit for each model is available torefurbish all connection seals.

GENERAL INFORMATION

Figure 3.1 Quick-Disconnect Hardware

Figure 3.2 Inlet Supply Strainer

14

Spray Nozzle Servicing

If the spray nozzle becomes clogged with dirt, excessivepump pressures may develop. A nozzle that has becomepartly clogged will demonstrate a pulsing sensation duringuse. If the nozzle becomes clogged or partially restricted, itcan be cleaned as follows:

1. Shut down the engine and turn off the water supply tothe pump.

2. Put on your safety glasses, as there could be trappedpressure behind a totally-clogged nozzle.

3. Disconnect the wand from the spray gun.

4. As seen in Figure 3.3, use a 5/64 inch (2mm) Allen wrenchto remove the nozzle from the end of the wand.

5. Use a length of wire similar to that seen in Figure 3.3 tofree any dirt from the nozzle.

NOTE: If desired, a 5/64 inch (2mm) wrench can beordered by specifying Generac nozzle kit partnumber 96961. A length of 17 gauge (0.039 inch)wire may be used to clean the nozzle. If desired, anozzle cleaning rod may be ordered by specifyingGenerac nozzle kit part number 96869.

6. Remove any additional dirt from the wand by back-flushing with water, as described below and shown inFigure 3.4.

a. Hold the water supply against the wand and back-flushfor about 30 seconds to 1 minute.

b. While flushing, move the nozzle collar between streamand spray positions and between the low and highpressure positions.

7. Use the 5/64 inch (2mm) Allen wrench to reinstall thenozzle into the wand. DO NOT OVERTIGHTEN.

8. Reattach the wand to the spray gun.

9. Reconnect the inlet water supply to the pump and turnon the water.

10. Start the engine and test operation.



Figure 3.3 Nozzle Removal and Cleaning

Figure 3.4 Back-flushing the Wand

15

Part 2 - LubricationAll pressure washers require oil lubrication of the pistonmechanism in order to maintain long-term reliability andservice. Certain early model Generac PortableProducts pressure washers incorporate sight glassesor dipsticks to be used to monitor pump oil levels. LaterGenerac Portable Products models haveimproved designs that eliminate the need to routinelymonitor oil levels or to change lubricating oil.

This section describes how to check and change pump oil onearly Generac Portable Products pressurewasher systems. If servicing a non-Generac PortableProducts-manufactured pump, please refer to themaintenance instructions provided with that specific system.

Check Pump Oil Level

Certain pressure washers may be equipped with a glass sightgauge, as depicted in Figure 3.5.

Always check pump oil level with the unit resting on a levelsurface. Oil should be at the full mark on the sight gauge(near the center). On units equipped with an oil dipstick, oillevel should be near the full mark. Add recommended pumpoil as required, to the full mark only.

Change Pump Oil

WARNING: DO NOT change pump oil unless thepressure washer Owners Manual requires this ANDyour pump is equipped with a pump drain plug.

Please refer to the maintenance instructions that wereshipped with your non-Generac PortableProducts-manufactured pump if it is necessary tochange pump oil. Pay particular attention to themanufacturers recommended torque values when tighteningdrain plugs and breather/dipstick caps.

To change oil in Generac Portable Products-manufactured pumps, refer to Figure 3.5 and proceed asfollows:

1. Place a suitable container under the pump drain plug.

2. Remove the oil fill cap (breather cap) from the top of thepump.

3. Remove the pump drain plug from the bottom of thepump. Drain oil completely into the container.

4. When all oil has drained, reinstall the pump drain plug andtighten to the torque value specified in the Torque Chart,found on the exploded view in the chapter for yourpump.

5. Insert a funnel into the oil fill cap opening and add therecommended oil until the oil level reaches the full mark.Oil capacity and type is listed in Part 1, earlier in Section3.

6. When oil is at the proper level, install and tighten the oilfill cap to the torque value specified in the Torque Chart,found on the exploded view in the chapter for yourpump.



Figure 3.5 Sight Gauge on Side of Pump

Item Name

1 Breather cap/oil fill location

2 Drain plug

3 Sight gauge location

16

Part 3 - StoragePump Storage

Water should not be allowed to remain in the pump forlong periods of time. Sediment can become deposited onpump parts, resulting in pump freeze-up.

To protect the pump against water sediment buildup,proceed as follows after each use:

1. If the chemical injection siphon was used, flush the systemas follows:

a. While running the pressure washer with the nozzle setto low pressure mode, place the chemical siphon tubeand its strainer into a pail of clear water.

b. Permit siphon action to continue for two or threeminutes to flush the system.

c. Shut off the engine and let it cool. Squeeze the spraygun trigger to relieve trapped line pressure. Thenremove all hoses.

WARNING: Never start the engine or operatethe pump unless the proper water supply isconnected. Any attempt to run the pump without thecorrect water supply will result in damage to thepump.

2. With the engine RUN/STOP switch in the STOP position,pull the engines recoil starter about six (6) times. Thisshould remove most of the liquid from the pump.

3. Drain water from the high pressure hose, then coil thehose and stow it properly.

4. Store the unit in a clean, dry area.

Protection Against Freezing

To protect the pump against freezing, proceed as follows:

1. Draw automotive windshield washer fluid into the pump:

a. Connect a three (3) foot length of garden hose to thepump inlet.

b. While holding the open hose end higher than thepump, pour the washer fluid into the length of hose.

c. With the engine RUN/STOP switch in the STOPposition, pull the engines recoil starter handle two orthree times. This should replace most of the water inthe pump with anti-freeze solution.

Purging Air From the System

Prior to use, the pressure washer pump, hose, and spray gunshould be purged of air. To do this, proceed as follows:

1. Prepare the pressure washer for use as outlined in theOwners Manual. Make sure a proper water supply isconnected and turned ON.

2. Put on your safety goggles and remove the wand from thespray gun.

3. Pull the trigger on the gun and hold open.

4. When the water flow is steady and constant, release thetrigger to turn off the flow.

5. Reattach the wand to the gun.

The system is now ready for use.



17

This section describes the small frame pump assemblies powered by electric motors. This small frame electric pump mayalso be referred to as EE or GPW-EE or Economy Electric pumps.

The small frame electric pump has the following features:

1100 to 1300 PSI water pressure

1.5 to 1.8 Gallons per minute flow

Axial Cam Design

Stainless Steel Pistons

Fixed Pressure Unloader

Chemical Injection System or Foamer Bottle available

Grip-Start - Automatically turns on the pump when spray trigger is pressed

Safety Flow switch - Pump will not operate unless water supply is turned on.

Oil bath, helical gear drive system

14 Amp Universal motor

Designed to UL 1097 Double Insulation standards

Part 1 - Specifications and ViewsPerformance specifications for Generac Portable Products small frame electric pumps, sectional and explodedviews, and a table showing recommended torque values are provided below.

Performance Specifications

+ Pressure (in pounds per square inch) is adjustable up to the unit's rated pressure.

* Flow rate is given in gallons per minute.

Pump assemblies are listed by part number and were current at time of publication. Other pump assemblies will becomeavailable as our products evolve.

SMALL FRAME ELECTRIC PUMP

Section 4 Small Frame Electric Pump


Model Rated Pump Head Flow Rate* Piston Oil Type/Part No. Pressure+ Material Capacity

0762-0 1250 Aluminum 1.5 Stainless Steel 80W90/60ml0776-0 1300 Aluminum 1.5 Stainless Steel 80W90/60ml0766-1 1250 Aluminum 1.5 Stainless Steel 80W90/60ml0793-0 1250 Aluminum 1.5 Stainless Steel 80W90/60ml1007-0 1250 Aluminum 1.5 Stainless Steel 80W90/60ml9606-0 1100 Aluminum 1.8 Stainless Steel 15W40/150ml9737-0 1150 Aluminum 1.8 Stainless Steel 15W40/150ml

18

Cross-Sectional View A typical small frame electric pump is shown in Figure 4.1 incross-section.



Figure 4.1 Small Frame Electric Pump (cross-sectional view)

19

Cross-Sectional View Parts List

Item Qty. Description

1 1 O-ring

2 4 O-ring

3 1 Shuttle valve spring

4 1 Shuttle valve

5 3 O-ring

6 3 Outlet port check valve cap

7 1 Tie wrap

8 2 O-ring

9 1 Motor assembly, complete

10 1 Motor cover housing

11 1 Housing and switch assembly

12 1 Foam air filter

13 1 Axial cam idler shaft

14 2 Bearing washer 35 x 55 x 3mm

15 1 Needle thrust bearing 35 x 52mm

16 1 Axial cam/gear assembly



19 3 SHCS M6-1.0 x 20mm


21 3 Piston spring retainer

22 1 Piston housing

23 3 Piston return spring

24 3 Oil seal

25 3 Pilot spacer

Item Qty. Description

26 3 High pressure water seal

27 4 Lock washer, M6 ribbed

28 4 SHCS M6- 1.0 x 35mm

29 3 Piston

30 1 Pump head

31 3 Inlet check valve

32 3 Outlet check valve

33 1 Hex socket set screw w/ LocktiteDO NOT REMOVE

34 1 Taper plug DO NOT REMOVE

35 1 Pop off valve spring

36 1 Pop off valve ball seat

37 1 Pop off valve check ball

38 1 O-ring

39 4 Rubber mount

40 2 Taptite screw, M4-0.7x10mm

41 4 Plastite screw, 6-19 x 0.75

42 1 Backup ring

43 1 O-ring

44 1 Auto switch piston return stop

45 1 Auto switch piston return spring

46 1 Auto switch piston assembly

47 1 Backup ring

48 1 Retainer cap

49 1 Auto switch grommet

50 1 Auto switch

51 1 Auto switch housing



20

Exploded View A typical small frame electric pump is depicted in explodedview in Figure 4.2.



Item Torque Value

6 15-17 ft-lbs

19 7-9 ft-lbs

28 9-12 ft-lbs

33 9-12 ft-lbs

40 2-4 ft-lbs

41 2-4 ft-lbs

48 10-12 ft-lbs

54 Brass: 15-23 ft-lbs

Nylon: 10-12 ft-lbs

57 20-30 in-lbs

Figure 4.2 Small Frame Electric Pump (exploded view)

21



Exploded View Parts List

Item Qty Description1 1 O-ring

2 4 O-ring

3 1 Shuttle valve spring

4 1 Shuttle valve

5 3 O-ring

6 3 Outlet port check valve cap

7 1 Tie wrap

8 2 O-ring

9 1 Motor assembly, complete

10 1 Motor cover housing

11 1 Housing and switch assembly

12 1 Foam air filter

13 1 Axial cam idler shaft



16 1 Axial cam/gear assembly



19 3 SHCS M6-1.0 x 20mm



22 1 Piston housing


24 3 Oil seal

25 3 Pilot spacer

26 3 High pressure water seal

27 4 Lock washer, M6 ribbed

28 4 SHCS M6- 1.0 x 35mm

29 3 Piston

Item Qty. Description30 1 Pump head

31 3 Inlet check valve

32 3 Outlet check valve

33 1 Hex socket set screw w/ LocktiteDO NOT REMOVE

34 1 Taper plug DO NOT REMOVE

35 1 Pop off valve spring

36 1 Pop off valve ball seat

37 1 Pop off valve check ball

38 1 O-ring

39 4 Rubber mount

40 2 Taptite screw, M4-0.7x10mm

41 4 Plastite screw, 6-19 x 0.75

42 1 Backup ring

43 1 O-ring

44 1 Auto switch piston return stop

45 1 Auto switch piston return spring

46 1 Auto switch piston assembly

47 1 Backup ring

48 1 Retainer cap

49 1 Auto switch grommet

50 1 Auto switch

51 1 Auto switch housing

52 1 Chemical suction hose

53 1 Hose clamp

54 1 Chemical inject fitting

55 1 Chemical inject check ball

56 1 Chemical inject check spring

57 1 Chemical inject venturi

58 1 Venturi o-ring

22

Part 2 - DisassemblyGeneral Information & Special Tools

NOTE: There are no special tools required todisassemble or reassemble this pump.

CAUTION: The pump is full of oil. Whenremoving pump from motor, drain by pouring oil outof crankcase.

Pump Head

Refer to Figure 4.3 for this procedure.

Using a 5mm Allen wrench, remove the four (4) M6-1.0 x 35 cap screws to separate pump head from pistonhousing.

To disassemble pump head:

1. Remove the three (3) high pressure water seals (item 2).Seals should slide out easily.

2. Remove the three (3) inlet check valves (item 1). A 5/16-18 bottoming tap may be used to remove thesevalves.

3. Remove the o-ring (item 3) from the pop off valve boss.

4. Secure the head in a vice or with a clamp and use an 8mmwrench to remove the three (3) M8-1.5 outlet port caps(items 5 & 6).

5. Remove the three (3) outlet check valves and o-rings(items 4 & 7).

6. Do not attempt to remove the pipe plug (item 10) fromthe head (item 15). It is installed with a thread-lockingcompound to secure the pop off components and is notmeant to be removed. Should these components bedamaged or broken, the entire head assembly must bereplaced.



Item Name

1 Inlet check valve assembly

2 High pressure water seal

3 Pop off o-ring

4 Outlet check valve assembly

5 Outlet port cap o-ring

6 Outlet port cap

7 Check valve o-ring

8 Taper plug DO NOT REMOVE

9 Pop off check ball

10 Hex socket plug DO NOT REMOVE

11 Pop off valve spring

12 Pop off ball seat

13 M6 ribbed lock washer

14 SHCS, M6-1.0 x 35mm

15 Pump head

Figure 4.3 Pump Head

23

Piston Housing Removal


Before disassembling the piston assembly, do the following:

1. Remove the three (3) pilot spacers (item 3). These willjust slide off.

2. Remove the three (3) check valve o-rings (item 4).

3. Remove the shuttle valve o-ring (item 5).

WARNING: There may be up to 50 pounds ofstored energy when separating the piston housingfrom the motor. Remove these bolts slowly andevenly.

4. Using a 5mm wrench, gradually loosen each of the three(3) M6-1.0 x 20 bolts that hold the motor to the pistonhousing, as seen in Figure 4.5.

NOTE: Piston housing is full of gear oil. Take careto handle the fluid safely.



Item Name

1 Piston housing

2 Piston

3 Pilot spacer


5 Shuttle valve o-ring

Item Name

1 Electric motor

2 SHCS, M6-1.0 x 20mm

3 Piston housing

Figure 4.4 Piston Housing

Figure 4.5 Motor Removal

24

Piston Housing Disassembly

Refer to Figure 4.6 for this disassembly, as follows:

1. Remove the large o-ring (item 1) from the housing.

2. Remove the three (3) pistons, springs, and retainers. Todo this, grasp the piston springs and pull straight out. Theretainers will stay attached to the pistons.

3. Remove the three (3) piston oil seals (item 6).


Not all pumps are equipped with a chemical injectionsystem. Refer to Figure 4.7 when following this disassemblyprocedure.

Be careful not to lose check ball and spring.

1. Remove the chemical injection fitting, check ball, andspring (items 3, 4, & 5).

2. Using a large straight tip screwdriver, unscrew andremove the chemical injection venturi and o-ring (items 1& 2) from discharge port.It may be necessary to insert a sheet metal screw into theventuri hole, then pull on the screw with a pliers, toremove the venturi and o-ring.



Item Name

1 Chemical inject venturi (brass or plastic)

2 Venturi o-ring

3 Chemical inject fitting

4 Check ball

5 Check spring

6 Piston housing

Item Name

1 Housing o-ring


3 Piston

4 Piston spring

5 Piston housing

6 Oil seal

Figure 4.6 Piston Housing Disassembly

Figure 4.7 Chemical Inject System

25

Auto Start Switch Assembly

Refer to Figure 4.8 when following this disassemblyprocedure.

1. Remove the housing covering the auto switch (item 4)and disconnect two spade lugs from the switch.

2. Remove two (2) 5.5mm Taptite screws (item 3) using a5.5mm socket. Remove the switch housing (item 4) fromthe piston housing.

3. Remove the retainer cap (item 11) with a 22mm socketor box wrench. Be careful to not round the hex headcorners on this plastic part.

NOTE: The retainer cap, spring, and piston partsmay show some slight differences depending onproduction date. Newer parts are completelyinterchangeable with older models.

4. Remove the piston spring and the piston components, asfollows:

a. To non-destructively remove the components, graspthe end of the piston shaft with a soft-jaw lockingpliers and lever the assembly out of its port, pryingagainst the port rim.

b. If no soft-jaw pliers are available, a short length ofbrass tubing can be slipped over the piston shaft. Astandard locking jaw plier can be used to grasp thetubing and squeeze it against the shaft, then remove asdescribed in (a.).

Any other removal method will require replacement of allauto switch piston components.



Item Name

1 Piston housing

2 Rubber diaphragm

3 Taptite screw

4 Auto switch housing

5 Auto switch

6 Auto switch piston spring

7 Auto switch piston assembly

8 O-ring

9 Auto switch piston return stop

10 Backup ring

11 Retainer cap

12 O-ring

13 Backup ring

Figure 4.8 Auto Start Switch Group

26

Axial Cam


1. Grasp the protruding end of the axial cam idler shaft(item 1) with your fingers and withdraw it from themotor housing (item 5).

2. Remove the two thrust washers and the needle bearing.

3. Remove the axial cam/gear assembly. Because the gear ispressed onto the cam with special factory tooling, thecam and gear must be replaced as an assembly.

5. Remove the remaining thrust washers and needle bearing.



Item Name

1 Axial cam idler shaft

2 Bearing washer

3 Axial cam/gear assembly

4 Needle thrust bearing

5 Motor

6 Bearing washer

7 Bearing washer


Figure 4.9 Axial Cam Components

27

Part 3 - InspectionSeals, O-Rings, and Gaskets

Once the pump is disassembled, make a careful inspection ofall seals and o-rings for any defects that may affect theproper operation of the pressure washer.

Piston & Spring Assemblies

Referring to Figure 4.10, inspect the three (3) pistonscarefully. Reject any piston that is scratched, dented, orotherwise damaged.

WARNING: Do not strike a piston with anyobject or use a piston to strike any object.Do notdrop the piston. Dropping the piston will result indamage.

Each of the three (3) pump pistons pass through an oil sealin the piston and unloader housing. Note the oil seal andpilot spacer illustrated in Figure 4.11. The oil seal lip will facetowards the piston spring and retainer to retain the pumpoil.

Inspect the three (3) piston springs. Replace any spring thatis damaged or broken.

Pump Head and Piston Housing

Clean all parts. Inspect carefully for cracks, damage, wear,etc.. Check for corrosion. Replace any damaged, defective,or corroded part as necessary.



Item Name


2 Piston

3 Piston return spring

Item Name

1 Piston, spring, and retainer

2 Piston housing

3 Oil seal

4 Pilot spacer


Figure 4.10 Piston & Spring Assemblies

Figure 4.11 Piston Seals

28

Axial Cam Drive Components

Referring to Figure 4.12, carefully inspect axial cam bearingassemblies for wear, damage, and freedom of rotation.Replace any damaged or defective bearing assembly.

Inspect the axial cam idler shaft. Replace if worn, bent, ordamaged.

Inspect the thrust washers. Replace if damaged.

Inspect the axial cam/gear assembly. Replace if wornexcessively or damaged.

Inspect the motor assembly, particularly the axial camhousing. Ensure that the axial cam idler shaft socket is trueand not worn or cracked. Ensure that the fastening bossesare not cracked or chipped. Inspect the housing for theabsence of cracks, chips, evidence of oil leaks, or otherdamage.

Inspect the motor drive gear for evidence of wear ordamage.

Inspect the motor wires for evidence of corrosion, frayingor damaged connectors, wires, or other defects.

Replace the motor assembly as a unit if any defects arefound.



Item Name


2 Bearing washer



5 Motor

6 Bearing washer

7 Bearing washer


Figure 4.12 Axial Cam Components

29

Part 4 - ReassemblyRefer to the Torque Specifications provided on thepump sectional view found at the beginning of thissection when reassembling this product.

Pump Head Assembly

The pop off valve is not serviceable. The entire headassembly must be replaced if a problem occurs in thesecomponents.

To assemble the pump head, refer to Figure 4.13 for thefollowing steps:

1. Install three (3) outlet check valve o-rings (item 7). Ensurethey lie flat at the bottom of the cavity.

2. Install three (3) outlet check valves, with large end first(item 4).

3. Install and snug the three (3) M18-1.5 outlet caps withpre-installed o-rings (items 5 & 6).

After the pump is assembled, tighten the three (3) outletcaps to the torque value specified in the Torque Chart,

found on Figure 4.2 (Exploded View) at the beginning of thischapter.

4. Press three (3) inlet check valves (item 1) into place.Notice that the small end of the valve goes into the cavityfirst, and that the valve is pressed in until it is flush withthe head surface. It may be necessary to pre-lubricate thecheck valve o-rings with silicone spray before installation.

5. Pre-lubricate three (3) high pressure water seals (item 2)with silicone spray. Insert a seal into each piston cylindercavity with the flat side facing out. Review Figure 4.11,seen earlier, for a view of proper seal orientation.

6. Install the pop off valve o-ring (item 3). Petroleum jellywill help to hold it in place.

Auto Start Switch Assembly

Refer to Figure 4.14 for this assembly.



Item Name

1 Inlet check valve assembly


3 Pop off valve o-ring

4 Outlet check valve assembly

5 Outlet port cap o-ring

6 Outlet port cap


8 Pump head

Item Name

1 Piston housing

2 Rubber diaphragm

3 Taptite screw

4 Auto switchhousing

5 Auto switch

6 Auto switch pistonspring

7 Auto switch pistonassembly

Item Name

8 O-ring

9 Auto switch pistonreturn stop

10 Backup ring

11 Retainer cap

12 O-ring

13 Backup ring

Figure 4.13 Pump Head

Figure 4.14 Auto Start Switch

30

Before assembly, ensure the auto switch cavity is clean andfree from scale, corrosion, dirt, etc.

1. If necessary, install new backup rings and o-rings (items 8,10, 12, 13) to the auto start piston return stop (item 7).

2. Remove and do not replace the teflon rings on the autoswitch piston assembly. These rings should be removedfor optimum auto switch operation.

3. Install the auto switch piston return spring (item 6) in theauto switch cavity on the piston housing.

4. Install the auto switch piston assembly, ensuring that itengages the spring inserted in step (3.).

5. Install the auto switch piston return stop (item 9) on thepiston shaft so that the small backup ring faces out.

6. Install the retainer cap (item 11) over the piston shaft andhand thread it into the piston housing.

7. Tighten the retainer cap to the torque value specified inthe Torque Chart, found on Figure 4.2 (Exploded View) atthe beginning of this chapter.

8. Ensure that the rubber diaphragm (item 2) is not damagedor perforated, and is installed in the hole in the side ofthe auto switch housing.

9. Using a 5.5mm socket, install two (2) Taptite screws tosecure the auto switch housing to the piston housing.Make sure the auto switch housing is anchored at themidpoint of its lateral adjustment.

After the pressure washer is assembled, it may be necessaryto adjust the position of the auto switch housing to ensureproper auto switch operation.

Chemical Inject Assembly


1. Install the check ball into the chemical inject fitting,followed by the spring (with the small end of the springtowards the ball).

2. Install the chemical inject fitting into the piston housing.Be careful not to drop the ball and spring.

3. Tighten the chemical injection fitting to the torque valuespecified in the Torque Chart, found on Figure 4.2(Exploded View) at the beginning of this chapter.

4. Carefully install the chemical inject venturi o-ring onto theventuri.

5. Hand thread the chemical inject venturi into the dischargeport of the piston housing.

6. Tighten the venturi to the torque value specified in theTorque Chart, found on Figure 4.2 (Exploded View) at thebeginning of this chapter.



Item Name

1 Chemical inject venturi (brass or plastic)

2 Venturi o-ring

3 Chemical inject fitting

4 Check ball

5 Check spring

6 Piston housing

Figure 4.15 Chemical Inject System

31

Piston Housing Assembly


1. Pre-lubricate the three (3) oil seals (item 5) with siliconespray. Press the seals into the piston housing with theirflat side (the side with writing on it) facing the installer. Ifyou see the seals internal spring, the seal has beeninstalled upside down.

2. Apply a small amount of 80W90 oil to the three (3)pistons, then install the pistons, springs, and retainers intothe piston housing. The pistons are merely pushed intoplace.

3. Invert the piston housing so that the pistons protrudevertically from the housing. Place the piston housing on aflat surface.

Pilot Spacer Installation


1. Install the three (3) check valve o-rings (item 4). Use asmall amount of petroleum jelly to hold them in place.

2. Install the three (3) pilot spacers (item 3) over thepistons, with large end inserted in piston housing.

3. Install the shuttle valve o-ring (item 5). Use a smallamount of petroleum jelly to hold it in place.

4. Carefully lift the pump head assembly, invert it, and alignthe high pressure water seals with the pistons protrudingfrom the piston housing.

5. Verify that the o-rings remain in their proper position andpress the head down to the piston housing.



Item Name


2 Piston

3 Piston spring

4 Piston housing

5 Oil seal

Item Name

1 Piston housing

2 Piston

3 Pilot spacer


5 Shuttle valve o-ring

Figure 4.17 Piston Housing

Figure 4.16 Pistons and Springs

32

Pump Head Bolts

1. Grasp the head/piston housing assembly and invert itonto a flat surface.

2. Install the four (4) M6-1.0 x 35 cap screws . Tighten thecap screws to the torque value specified in the TorqueChart, found on Figure 4.2 (Exploded View) at the beginningof this chapter.

Assemble Axial Cam

Refer to Figure 4.18 for this procedure:

1. Invert the head/piston housing assembly and place it on aflat surface. Ensure that the pistons are fully inserted intothe piston housing.

2. Install the axial cam idler shaft (item 7) into its socket inthe piston housing (item 8).

3. Install a 36 x 60 x 6mm thrust washer (item 6) on theidler shaft, with chamfer towards the pistons.

4. Lay a 40 x 60mm needle bearing (item 5) on the thrustwasher, either side up.

5. Lay a 40 x 60 x 1mm thrust washer (item 4) on theneedle bearing, chamfer side up.

6. Install the axial cam/gear assembly (item 3) onto the idlershaft, gear end on top. Ensure that the axial cam engagesthe bearing and thrust washers previously installed.

7. Install a 35 x 55 x 3mm thrust washer (item 2) on theaxial cam, with chamfer towards the cam.

8. Install a 35 x 52mm needle thrust bearing (item 1) on thethrust washer (either side up).

9. Install the large o-ring into the piston housing groove.

10. Ensure that the idler shaft protrudes from the axialcam/bearing assembly about 8mm. This will make motoralignment easier.

Oil Fill

Pour the specified amount of 80W90 oil into the pistonhousing. For specific recommendations for oil type andcapacity, please refer to the table given in Part 1, at thebeginning of this section.

Main Component Assembly

1. Use a dab of petroleum jelly to adhere the remaining 35 x55 x 3mm thrust washer in its recess in the motorhousing, with chamfer towards the motor housing.

2. Grasp the motor assembly with both hands and invert itover the piston housing so that the axial cam idler shaftaligns with the mating hole in the motor housing. Gentlylower the motor and rotate the cam to ensure the gearteeth engage the motor drive gear teeth.

3. Align the mounting screw holes on the motor housingwith the threaded holes on the piston housing.



Item Name


2 Bearing washer


4 Bearing washer


6 Bearing washer


8 Pump head/piston housing assembly

Figure 4.18 Axial Cam Assembly

33

CAUTION: The motor adapter bolt holes line upwith the holes on the piston housing in one positiononly. Rotate the motor housing until properalignment is achieved.

4. Referring to Figure 4.19, install the three (3) M6-1.0 x 20socket head cap screws into the mounting screw holes onthe motor housing and thread them into the pistonhousing. Because of piston return spring tension, themotor housing will remain elevated.

5. Snug each M6-1.0 cap screw, alternating between screwsuntil the housings meet. Tighten screws to the torquevalue specified in the Torque Chart, found on Figure 4.2(Exploded View) at the beginning of this chapter.

Final Assembly and Test

NOTE: Torque the outlet caps at this time, if notdone previously. Verify that all other fasteners havebeen torqued to proper values.

1. Position the motor cover housing over the pumpassembly, feeding the two white wires up through thechannel in the housing, as show on Figure 4.1.

2. Insert the bayonet plug into its mating connector in thehousing and switch assembly.

3. Insert the spade connector into its mating spade lug in thehousing and switch assembly.

4. Fasten the housing and switch assembly to the motorcover housing with four (4) Plastite 6-19 x 0.75 screws.

5. Reassemble the pump into the pressure washer housing,taking care to avoid pinching wires, etc.

6. Cthe pressure washer to a water supply and connect thehigh pressure hose, wand, and spray gun. Connect thepressure washer to line voltage through a GFCIreceptacle.

7. The pressure washer should provide a spray when thespray gun trigger is depressed. If the unit does notproduce a spray, the auto switch may need to beadjusted, as follows:

a. Disconnect the pressure washer from line voltage andfrom the water supply.

b. Disassemble the unit so that you can get to the twotaptite screws.

c. Loosen the screws enough to be able to laterally movethe auto switch housing further away from the pistonhousing.

d. Tighten the taptite screws to recommended torquevalue.

e. Reassemble the unit, reconnect the water and linevoltage and depress the spray gun trigger again.Normal unit operation should be obtained.



Item Name

1 Electric motor

2 SHCS, M6-1.0 x 20mm

3 Piston housing

Figure 4.19 Motor Assembly

34



Part 5 - Troubleshooting

1. Water leakage between pump head andpiston housing.

a. Head bolts improperly torqued.

b. Damaged head.

c. Missing or damaged o-rings

a. Torque head bolts.

b. Replace head.

c. Install new o-rings.

2. Water leaks from pressure outconnector.

a. Connector not properly sealed.

b. Damaged connector.

a. Seal with teflon tape and tightenproperly.

b. Replace bad connector.

6. Detergent does not mix with spray. a. Nozzle is in high pressure mode.

b. Chemical suction line is not submerged.

c. Chemical suction strainer or line isclogged.

a. Reset nozzle to low pressure.

b. Insert line into fluid.

c. Clean or replace strainer or line.

3. Oil leak between motor and motoradapter.

a. Defective or missing motor adapter o-ring.

b. Motor adapter cap screws not tightenedproperly.

a. Install new o-ring.

b. Tighten to correct torque.

4. Oil leak between motor adapter andpiston/unloader housing.

a. Missing or bad o-ring seal.

b. Cap screws not tightened properly.

a. Install new o-ring seal.

b. Tighten to correct torque.

5. Pump does not produce pressure,exhibits erratic pressure, chatters, or hasa low water volume.

a. Nozzle is set to low pressure mode.

b. Incorrect spray nozzle is used.

c. Spray nozzle is obstructed.

d. Water Inlet blocked

e. Inadequate water supply to pump.

f. Water supply hose kinked or leaking.

g. Clogged inlet hose strainer.

h. Water supply too hot.

i. Worn or defective pump.

a. Reset nozzle to high pressure.

b. Replace with correct nozzle.

c. Clear obstruction from nozzle.

d. Clear inlet.

e. Provide sufficient water supply.

f. Relieve kinking or repair leak.

g. Clean strainer.

h. Reduce inlet water temperature tobelow 140oF.

i. Disassemble and repair pump.

Problem Possible Cause Corrective Action

35

This section describes the small frame pump assemblies powered by gasoline engines intended for use in light dutyapplications. This small frame gas pump may also be referred to as GPW-EG or EG or Economy Gas pumps. Most of theinformation previously printed in publication A4453 will be found here.

The small frame gas pump has the following features:

1500 to 1800 PSI water pressure

2.0 Gallons per minute flow

Axial Cam Design

Stainless Steel Pistons

Fixed Pressure Unloader

Chemical Injection System available

Thermal Relief Valve available

Oil Bath Drive System

Vertical or Horizontal Engine Mount

Part 1 - Specifications and ViewsThis section presents the torque and performance specifications for Generac Portable Products small framegas pumps. Also presented are sectional and exploded views of this type of pump assembly.

Performance Specifications

+ Pressure (in pounds per square inch) is adjustable up to the unit's rated pressure.

* Flow rate is given in gallons per minute.

A suffix denotes pumps with thermal relief valve.

Pump assemblies are listed by part number and were current at time of publication. Other pump assemblies will becomeavailable as our products evolve.

SMALL FRAME GAS PUMP

Section 5 Small Frame Gas Pump


Pump Rated Engine Pump Head Flow Rate* Piston Oil Type/Assembly Pressure+ Shaft Material CapacityPart No.

B1906A 1500 Straight Aluminum 2.0 Stainless Steel 80W90/120ml20965 1650 Straight Aluminum 2.0 Stainless Steel 80W90/120ml

20965A 1650 Straight Aluminum 2.0 Stainless Steel 80W90/120mlB1262 1750 Straight Aluminum 2.0 Stainless Steel 80W90/120ml

B1262A 1750 Straight Aluminum 2.0 Stainless Steel 80W90/120ml

36

Cross-Sectional view A typical small frame gas pump is shown in cross-section inFigure 5.1.



Figure 5.1 Small Frame Gas Pump (cross-sectional view)

37

1 3 Rubber grommet spacer sleeve

2 1 Cage needle bearing assembly

3 1 Bearing washer

4 1 Bearing washer

5 3 Oil piston seal


7 3 U-cup seal

8 1 Axial cam w/insert

9 1 Engine adapter

10 1 Piston and unloader housing


12 3 Pilot spacer

13 3 Piston

14 1 Pump head

15 1 Radial ball bearing

16 6 Rubber bushing


O-Ring seal

18 1 High pressure transfer O-Ring

20 6 Check valve assembly

21 3 Outlet check valve cap O-Ring

22 1 Thermal relief valve (if equipped)

w/sealant

23 3 Outlet check valve cap

24 1 Unloader seat

25 1 Unloader seat O-Ring

26 1 Unloader piston

27 2 Unloader split-ring seal

28 1 Unloader spring

29 1 Unloader cap O-Ring

30 1 Unloader cap

31 1 Pipe plug (if item 22 notequipped) w/sealant

32 1 Chemical injection hose barb

33 1 Plug, w/sealant

34 1 Chemical injection ball

35 1 Chemical injection spring

36 1 Chemical injection venturi

37 6 Low pressure transfer O-Ring

39 7 Lock washer

40 4 Socket head cap screw

M6-1.0 x 35


M6-1.0 x 25

43 1 Venturi O-Ring



Item Qty. Description Item Qty. Description

Cross Sectional View Parts List

38

Exploded View A typical small frame gas pump is shown in exploded view inFIgure 5.2.



Torque Chart

Item Torque

23 15-17 ft-lbs

30 Brass: 15-18 ft-lbs

Plastic: 7-10 ft-lbs

31 15-18 ft-lbs

32 9-12 in-lbs

33 12-15 ft-lbs

36 20-30 in-lbs

40 9-12 ft-lbs

42 9-12 ft-lbs

43 15-18 ft-lbs

Figure 5.2 Small Frame Gas Pump (exploded view)

39

1 3 Rubber grommet spacer sleeve

2 1 Cage needle bearing assembly

3 1 Bearing washer

4 1 Bearing washer

5 3 Oil piston seal


7 3 U-cup seal

8 1 Axial cam w/insert

9 1 Engine adapter



12 3 Pilot spacer

13 3 Piston

14 1 Pump head

15 1 Radial ball bearing

16 6 Rubber bushing


O-Ring seal

18 1 High pressure transfer O-Ring

20 6 Check valve assembly

21 3 Outlet check valve cap O-Ring

23 3 Outlet check valve cap

24 1 Unloader seat

25 1 Unloader seat O-Ring

26 1 Unloader piston

27 2 Unloader split-ring seal

28 1 Unloader spring

29 1 Unloader cap O-Ring

30 1 Unloader cap

31 1 Pipe plug (if item 43 notequipped) w/sealant

32 1 Chemical injection hose barb

33 1 Plug, w/sealant

34 1 Chemical injection ball

35 1 Chemical injection spring

36 1 Chemical injection venturi

37 6 Low pressure transfer O-Ring

39 7 Lock washer


M6-1.0 x 35


M6-1.0 x 25

43 1 Thermal relief valve (if equipped)

w/sealant

45 1 Venturi O-Ring



Item Qty. Description Item Qty. Description

Exploded View Parts List

40

Part 2 - DisassemblyGeneral Information & Special Tools

NOTE: There are no special tools required todisassemble or reassemble this pump.

CAUTION: The pump is full of oil. Whenremoving pump from engine, drain by pouring oil outof port used by the crankshaft.

Pump Head


Using a 5mm Allen wrench, remove the four (4) M6-1.0 x35 cap screws and lockwashers to separate pump head frompiston housing.

To disassemble pump head:

1. Remove the three (3) water seals. Seals should slide outby hand.

2. Remove the three (3) inlet check valves. A 5/16-18bottoming tap may be used to remove these valves. DONOT use a screwdriver as it will damage valve and head!

3. Remove the O-Ring from the high pressure transfer boss.

4. Remove the three (3) M8-1.5 outlet check valve caps andO-Rings.

5. Remove the three (3) outlet check valves and O-Rings.

6. Do not attempt to remove the pipe plug (item 7). It isinstalled with a thread-locking compound and is notmeant to be removed.

Piston & Unloader Housing Removal


Before disassembling the piston and unloader assembly, dothe following:

1. Remove the three (3) pilot spacers. These will just slideoff.



Figure 5.3 - Pump Head

Item Name

1 Water seal

2 Check valve

3 Low pressure transfer O-Ring

4 High pressure transfer O-Ring

5 Outlet check valve cap

6 Outlet check valve cap O-Ring

7 Pipe Plug - If present, DO NOT REMOVE

8 M6 lock washer

9 M6-1.0 x 35 cap screw

Figure 5.4 - Pump-Adapter Assembly

Item Name

1 Piston

2 Pilot spacer


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2. Remove the three (3) low pressure transfer O-Rings.

WARNING: There may be up to 75 pounds ofstored energy when separating the piston andunloader housing from the engine adapter housing.Remove these bolts slowly and evenly.

3. Apply a 6 C-clamp to hold the engine adapter and thepump head together.

4. Remove the three (3) M6-1.0 x 25 cap screws that holdthe engine adapter to the piston and unloader housing, asseen in Figure 5.5.

5. Slowly loosen the C-clamp until spring tension is releasedand the components separate.

Piston & Unloader Housing Disassembly

Refer to Figure 5.6 for this disassembly, as follows:

1. Remove O-Ring from housing.

2. Remove the three (3) pistons, springs, and retainers. Todo this, grasp the piston springs and pull straight out. Theretainers will stay attached to the pistons.

3. Remove the three (3) piston oil seals.

4. Remove the thermal relief valve (if present). It is notnecessary to remove the pipe plug, if installed in place ofthe thermal relief valve.



Figure 5.6 - Piston & Unloader Housing

Item Name

1 O-Ring

2 Piston and retainer

3 Spring

4 Thermal bypass valve or pipe plug

5 Piston and unloader housing

6 Piston oil seal

Figure 5.5 - Engine Adapter

Item Name

1 M6-1.0 x 25 cap screw & M6 lock washer

2 Engine adapter

42


Refer to Figure 5.7 and follow this chemical injection systemdisassembly procedure.

CAUTION: Be careful not to lose check ball andspring.

1. Remove the chemical injection fitting, check ball, andspring.

2. Using a large straight tip screwdriver, unscrew andremove the chemical injection venturi and O-Ring fromdischarge port.

Unloader


CAUTION: Unloader cap is under strong springpressure.

1. Remove the M25-1.0 unloader cap with a 24mm wrench.

NOTE: Unloader cap, unloader spring, andunloader piston parts may show some slightdifferences depending on production date. If theentire unloader system is replaced, newer assembliesare completely interchangeable with older models.

2. Remove the unloader spring and the unloader piston.These pieces should just slide out.

3. Remove the unloader seat by inserting a 90 O-Ring pickinto the orifice machined in the side of the seat, thengently pull the seat out of the housing.



Item Name


2 O-Ring

3 Unloader seat

4 Unloader piston

5 Unloader cap

6 Unloader spring

7 Split-ring seal

Figure 5.7 - Chemical Injection System

Item Name


2 O-Ring

3 Barbed nipple

4 Check ball

5 Spring


Figure 5.8 - Unloader Parts

43

Engine Adapter


1. Remove the thrust washer.

2. Remove the cage needle bearing.

3. Remove the retainer washer.

4. Remove the axial cam/radial ball bearing assembly.Because the bearing is pressed onto the cam, the cam andbearing must be replaced as an assembly.

5. If present, the pipe plug was installed with a thread-locking compound and should not be removed.

Part 3 - InspectionSeals, O-Rings, and Gaskets

Once the pump is disassembled, make a careful inspection ofall seals and O-Rings for any defects that may affect theproper operation of the pressure washer.

Piston & Spring Assemblies

Referring to Figure 5.10, inspect the three (3) pistonscarefully. Reject any piston that is scratched, dented, orotherwise damaged.

CAUTION: Do not strike a piston with any objector use a piston to strike any object.Do not drop thepiston. Dropping the piston will result in damage.



Figure 5.9 - Engine Adapter & Axial Cam

Item Name

1 Thrust washer

2 Cage needle bearing

3 Retainer washer

4 Axial cam

5 Radial ball bearing

6 Engine adapter

Figure 5.10 - Piston Assembly

Item Name

1 Retainer

2 Piston

3 Spring

44

Each of the three (3) pump pistons pass through an oil sealin the piston and unloader housing. Note the oil seal andpilot spacer illustrated in Figure 5.11. The oil seal lip will facetowards the piston spring and retainer to retain the pumpoil.

Inspect the three (3) piston springs. Replace any spring thatis damaged or broken.

Engine Adapter, Pump Head, and Piston & UnloaderHousing

Clean all parts. Inspect carefully for cracks, damage, and soforth. Check for corrosion. Replace any damaged, defective,or corroded part as necessary.

Axial Cam Drive Components

Referring to Figure 5.12, carefully inspect the engine adapterbearing and the axial cam bearing assemblies for wear,damage, and freedom of rotation. Replace any damaged ordefective bearing assembly.

Inspect the retainer washer and the thrust washer. Replaceif damaged.

Inspect the axial cam. Replace if worn excessively ordamaged.



Figure 5.11 Piston Chamber

Item Name


2 Piston

3 Oil seal

4 Pilot spacer

5 Pump head

Figure 5.12 - Axial Cam Drive Components

Item Name

1 Thrust washer

2 Cage needle bearing

3 Retainer washer

4 Axial cam

5 Radial ball bearing

6 Engine adapter

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Part 4 - Reassembly

NOTE: Refer to the Torque Specifications providedon the pump exploded view found at the beginning ofthis section when reassembling this product.

Engine Adapter

1. Install the retainer washer (thinner one) on the axialcam/radial ball bearing assembly.

2. Install the cage needle bearing (either side up).

3. Install the thrust washer (thicker one, either side up).

Unloader Assembly


1. Install the new O-Ring on the unloader seat (if replacing).

2. Install the unloader seat with O-Ring (use a small amountof petroleum jelly on O-Ring if necessary). Seat will pressitself into place when unloader piston, spring, and cap areinstalled.

3. Install the new split-ring seal onto the unloader piston (ifreplacing).

4. Install the unloader piston. It will seat itself inside of theunloader seat.

5. Install the unloader spring.

6. Install the M25-1.0 unloader cap and O-Ring.

7. Tighten the unloader cap to the torque value specified inthe Torque Chart, found on Figure 5.2 (Exploded View) atthe beginning of this chapter.

Chemical Injection Assembly


1. Install the check ball into the chemical injection nipple,followed by the spring (with the small end of the springtowards the ball).

2. Install the M10-1.0 chemical injection nipple into thepiston and unloader housing. Be careful to not drop theball and spring.

3. Tighten the chemical injection nipple to the torque valuespecified in the Torque Chart, found on Figure 5.2(Exploded View).



Figure 5.14 - Chemical Injection System

Item Name


2 O-Ring

3 Barbed nipple

4 Check ball

5 Spring


Figure 5.13 - Unloader Assembly

Item Name


2 O-Ring

3 Unloader seat

4 Unloader piston

5 Unloader cap

6 Unloader spring

7 Split-ring seals

46

4. Install the chemical injection venturi O-Ring into thepiston and unloader housing.

5. Hand thread the M14-1.25 chemical injection venturi intothe housing.

6. Tighten the venturi to the torque value specified in theTorque Chart, found on Figure 5.2 (Exploded View).

Piston & Unloader Housing Assembly


1. Refer to Figure 5.15 and install the three (3) oil seals.Press the seals into the piston and unloader housing usinga small amount of petroleum jelly.

NOTE: Do not reuse springs color coded RED. Allpiston return springs must be replaced in sets ofthree (3).

2. Apply a small amount of 80W90 oil to the three (3)pistons, then install the pistons, springs, and retainers intothe piston and unloader housing. The pistons are merelypushed into place.

3. Install the thermal relief valve (item 3).

4. Tighten the thermal relief valve (or substitute plug) to thetorque value specified in the Torque Chart, found on Figure5.2 (Exploded View) at the beginning of this chapter.

Pump Head Assembly


1. Install the three (3) low pressure transfer O-Rings. Use asmall amount of petroleum jelly to hold them in place.

2. Install the high pressure transfer O-Ring. Petroleum jellywill help to hold it in place.



Figure 5.15 - Piston & Unloader Housing

Item Name

1 O-Ring

2 Piston and retainer

3 Spring

4 Thermal bypass valve or pipe plug


6 Piston oil seal

Figure 5.16 - Pump Head

Item Name

1 Water seal

2 Check valve


4 High pressure transfer O-Ring

5 Outlet check valve cap

6 Outlet check valve cap O-Ring

7 Pipe Plug - If present, DO NOT REMOVE

8 M6 lock washer


47

3. Press three (3) inlet check valves into place, as shown inFigure 5.16.

4. Install three (3) outlet check valves, observing theirorientation, as shown in Figure 5.16.

5. Install the three (3) M18-1.5 outlet caps and O-Rings.

6. After the head is bolted to the pump, tighten the three(3) outlet caps to the torque value specified in the TorqueChart, found on Figure 5.2 (Exploded View) at thebeginning of this chapter.

Main Component Assembly


1. Place the pump head assembly on a flat surface, with theinner side up.

2. Position the piston and unloader housing on the pumphead so that the pistons line up with their respectivecylinders in the pump head.

3. Place the piston housing O-Ring into the groove on thehousing.

4. Grasp the engine adapter with both hands and invert itwhile holding the axial cam, washers, and bearing in place.

5. Place the engine adapter over the piston housing so thatthe thrust bearing is touching all three (3) pistons, and themounting screw holes on the adapter line up with thethreaded holes on the housing.

6. Referring to Figure 5.18, install the three (3) M6-1.0 x 25socket head cap screws into the mounting screw holes onthe engine adapter and thread them into the pistonhousing.

7. Tighten the M6-1.0 cap screws to the torque valuespecified in the Torque Chart, found on Figure 5.2(Exploded View) at the beginning of this chapter.

NOTE: The engine adapter bolt holes line up withthe holes on the piston housing in one position only.Use the widest of the three openings between theengine adapter legs as a reference. This openingshould line up roughly with the chemicalinjection/thermal relief valve side of the pistonhousing.



Figure 5.18 Installing Engine Adapter Bolts

Item Name

1 M6-1.0 x 25 cap screws & M6 lock washers

2 Engine adapter

3 Widest opening between three (3) engine adapterlegs aligns with the chemical injector-thermal relief side of piston and unloader housing

4 Pump head

Figure 5.17 Main Component Assembly

Item Name

1 Engine adapter assembly with axial cam, bearings,and washers held in place.

2 Assembled piston and unloader housing withpistons, seals, and O-Ring

3 Pump head assembly placed on flat surface

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Pilot Spacer Installation

1. Grasp the complete pump assembly with both hands andturn it over onto the three (3) engine adapter legs, asshown in Figure 5.19.

2. Carefully lift the pump head from the pump and slide thethree (3) pilot spacers over the pistons, which will beprotruding from the piston housing.

3. Install the three (3) low pressure transfer O-Rings aroundthe inlet openings on the piston housing, as seen in Figure5.20.



Figure 5.19 Invert Pump Assembly

Figure 5.20 Install Pilot Spacers/O-Rings

Item Name

1 Pump head

2 Pilot spacer


4 Piston

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Pump Head Bolts

Referring to Figure 5.21, reposition the pump head andinstall the four (4) M6-1.0 x 35 cap screws.

Tighten the M6-1.0 cap screws to the torque value specifiedin the Torque Chart, found on Figure 5.2 (Exploded View) atthe beginning of this chapter.

NOTE: Torque the outlet check valve caps at thistime, if not done previously.

Oil Fill

As shown in Figure 5.22, set the pump on its head. Pour inthe specified amount of 80W90 oil through the port used bythe engine crankshaft.

Verify that the oil level reaches the upper lip of the pistonhousing, as shown in Figure 5.23. The pump can now beinstalled onto the engine.

For specific recommendations for oil type and capacity,please refer to the table given in Part 1, at the beginning ofthis section.



Item Name


2 M6 lock washer

3 Piston & unloader housing attached toengine adapter

Figure 5.23 Oil Level

Figure 5.22 Oil FillFigure 5.21 Head Bolt Installation

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Part 5 - Troubleshooting

1. Water leakage between pump head andpiston housing.

a. Head bolts improperly torqued.

b. Damaged head.

c. Missing or damaged o-rings

a. Torque head bolts.

b. Replace head.

c. Install new o-rings.

2. Water leaks from pressure outconnector.

a. Connector not properly sealed.

b. Damaged connector.

a. Seal with teflon tape and tightenproperly.

b. Replace bad connector.

6. Detergent does not mix

B3277GS Pressure Washer Pumps by Generac

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Transcript of B3277GS Pressure Washer Pumps by Generac