Cummins EFC Troubleshooting Guide

CUMMINS INDIA LIMITED

ELECTRIC FUEL CONTROL GOVERNOR

CUMMINS DIESEL SALES & SERVICE (I) LTD

35A/ 1 / 2 , Erandwana, Pune 411 038.

1

FOREWORD

The electric fuel control ( EFC) governor is used on the PT fuel system. The EFC

governor can be adjusted for isochronous or droop applications.

This TROUBLE SHOOTING GUIDE contains a list of trouble symptoms & their

solutions for solving problems on both indigenous & imported EFC governors fitted

on Generator drive applications.

Cautions & Warnings!

1. Do not connect governor Power supply terminals directly to the battery

charger. Connect the Power supply terminals with the correct polarity to the

battery directly, without looping with the other equipments. Do not

disconnect battery while engine is in running condition. For checking

continuity & resistances of any EFC Components , Please disconnect the

battery supply.

2. Do not apply external supply / 24 V directly across the controller terminals 6 ,

7,(for indigenous) & 3 & 4 (for imported) ---- Actuator connections.

For giving 24 V to actuator for testing purpose, remove the connections of the

actuator terminals & then give supply to the actuator .

3. Use proper screwdriver for adjustment of potentiometers.

4. Check the ripple voltage on D.C. supply using AC range on a DIGITAL

MULTIMETER, on Power supply terminals of the controller. It should be

less than 1.5 Vac

5. Handle the actuator with great care, never hold it by its sleeve. Always hold it

by its base only.

6. When battery supply to the Solid State Potentiometer ( SSP) is disconnected , it

has be set again when reconnected. Do not disconnect the power supply to the

SSP .

7. While reporting a problem or for a warranty claim duly filled check list of the

related symptom & the basic checks must accompany the service report.

2

PREFACE

Majority of the problems are generated because of ...

• Dirt & air entry in the fuel system

• Improper DC voltage supply.

• RPM signal distortion due to improper shielding.

• Improper adjustment on the EFC controller.

• Improper wiring.

The following Basic checks will take care of the above mentioned causes. These checks

are mandatory for all problems related to EFC

Tools required:

Digital multimeter(Do not use analog meter)

EFC Manual.

Small screwdriver.( Taparia Make - No.911)

Allen key size - 3/ 32"

Remember! Once set properly, EFC controller does not

need frequent adjustments ! ! !

Please float all your querries / suggestions / additions / deletions / improvements /

feedbacks, to the Electronics Cell at CDS&S (I) Ltd. PUNE

3

Basic Checks.

Wiring Checks. ( Cold Checks )

1 : Check wiring as per the wiring diagram of the engine model . Please refer the

respective product user manual for correct wiring part number.

For Indeginious EFC Controller : Bulletin No. 3243692-00

For Imported EFC Controller : Bulletin No. 3379231-03

2 : Check end to end continuity of the harness at the same time see that the particular

wire is not shorted with any other wire and is not showing continuity with it. This test is

to conform electrical connections. Also check end to end continuity of the shield ( wire)

& make sure that only one end of the shield is connected to negative of the battery, the

other end remains open.

1 : Mag Pick up

Part Desired reading Actual reading Action

a : Resistance of Mag. Pick Up 80 - 1600 Ohms -------Ohms Replace in

with & with out connector. case of Deviation

b : Check for body short* > 100K Ohms --------Ohms Replace in

case of Deviation

c : Gap between the tip of the 0.028” to 0.042” --------More /less Correct

pick up and ring gear tooth tip.

4

2 : Actuator


a : Actuator Resistance 7 to 9 Ohms -------Ohms Replace in

case of Deviation

b : Check for body short* >100K Ohms -------Ohms Replace in

case of Deviation

3 : Remote Potentiometer( For KCL controller)


a : Total Resistance 10 K Ohms -------Ohms Replace in

case of Deviation

b : With respect to variable terminal 0 - 10K Ohms -------Ohms Replace in

case of Deviation

4: Remote Potentiometer (For Imported Controller)


a : Total Resistance (120 + 5) K Ohms ------Ohms Replace in

case of Deviation

b : With respect to variable terminal 0 to (120 + 5)K Ohms ------Ohms Replace

incase of Deviation

SOLID STATE POTENTIOMETER :

FOR INDIGENOUS CONTROLLER ( 3873853 ) USE SSP WITH P.No. 3877372.

FOR IMPORTED CONTROLLER (3062322 ) USE SSP WITH P.No 3392055.

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SERVICE PARTS TOPICS : FOR INDIGENOUS SYSTEM USE SPT No. 3242526.

:FOR IMPROTED SYSTEM USE SUPPLEMENTNo.3379231.

CABLES TO BE USED WITH SSP'S :

a. For connecting out put & ground terminals ( of SSP ) to controller terminals 1 & 2

( for indigenous controller) / 8 & 11 of imported controller --use 2 core 1.5 sq. m.m

shielded cable.

b. For connecting -- Raise input & lower input on to the panel --- use 1 Sq. m.m wire.

a. Power supply connection : Use 1.5 Sq. m.m wire.

Check the above wiring & replace in case of any deviation.

For detailed connection -- Refer respective diagrams enclosed herewith.

For checking the Solid State Potentiometers :

1. Give 24 Vdc supply to the Power supply terminals of the SSP.

2. Connect the multimeter ( d.c.range --40V ) to terminals output & common of the SSP.

3. Press the raise button on the SSP & observe the voltage rise on your multimeter,

simultaneously see that the Raise LED on the SSP is Glowing. Also observe the Limit

red LED glowing when the Out put reaches the limit. ----

4. For SSP with P.No. 3877372 --- O/p varies from 0Vdc to 2Vdc.

For SSP with P.No. 3392055 --- O/p varies from 4Vdc to 6Vdc.

5. Similarly press the lower button & check if the voltage goes down & the limit LED

glows when the voltage reaches the lower limit.

IF ANY LED'S OF THE SSP IS NOT GLOWING WHEN THE PARTICULAR

FUNCTION IS ON THEN REPLACE THE SSP.

For Ex : When the Raise button is pressed -- the raise LED should glow.

: When the raise limit is reached --the raise LED with the Limit LED should Glow.

CAUTION : IF THE POWER SUPPLY TO THE SSP IS DISCONNECTED,

THE SSP HAS TO BE SET AGAIN IF RECONNECTED. THEREBY POWER

SUPPLY TO THE SSP SHOULD NOT BE DISCONNECTED AT ANY TIME.

In cases of problems like hunting or engine overspeeding etc , please disconnect the

Potentiometer & carry out the trouble shooting. Potentiometer can also be the cause

of the problem.

5 : Run / Idle Switch ( Continuity between two terminals )

6


a : In RUN mode ( open) >100K Ohms ------Ohms Replace

incase of

Deviation

b : In Idle mode ( Close ) <100 Ohms ------Ohms Replace

incase of

Deviation

( Repeat the test for 5 to 6 times rapidly to confirm the switch operation)

*Procedure to check for body short : Attach one probe to one of the terminals of the

component & other probe to the body of the component under test. There should be very

high resistance shown between these two probes ( more than 100 K Ohms ). In some

case you may get “OL” reading on your multimeter which indicates that body test of that

part is OK.

6 : Battery to controller- cable

Part Desired reading Actual reading

Action

a : DC Voltage supply to controller Directly from Battery Yes / No.

Correct

b : Cable size 1 Sq. mm Multistrand ....... Sq. mm Correct Note : Supply should be directly taken from the battery ( without any toggle switch or

battery

charger in between).

7 : Remote Potentiometer-cable


a : Cable specifications 1sq mm, 3 core , Give specs... Replace

incase of

flexible, shielded Deviation

Voltage Checks ( Hot Checks )

8 : Battery Voltage.

7


a : When engine is running 20 to 28 Volts DC .........Volts DC Restore

/Replace

b : At the time of cranking 18 Volt DC minimum ........Volts DC Restore

/Replace

9 : Ripple voltage on Battery.


a : AC ripple on Battery < 2 volts AC. ..........Volts AC Restore

/Replace

( Measure the terminal voltage of the battery with AC range on the multimeter. )

Steps to Detect & Eliminate the ripple source : 1. External Charger : With the charger ON check the ripple voltage. Then disconnect

the charger & again check the ripple voltage again. If the value is lesser than the

earlier reading then replace / repair the charger.

2. Battery Charging alternator : With all the connections intact check the ripple

voltage, if this voltage is more then disconnect the charging alternator connections at

the alternator end & check the ripple. Now if the ripple voltage is in limits then repair/

replace the charging alternator.

10 : Magnetic Pick up output.


a : At the time of cranking 1.5 Volts AC minimum ......Volts AC Check gap/

Restore gap/

ReplaceMPU

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11 : Actuator .


a :* Click test inside the housing OK OK / Not OK

Replace

b : Click test outside the housing OK OK / Not OK

• Actuator Click Test: Make sure that the wires from the actuator terminal &

controller are disconnected. Give direct 24 volts dc supply to the actuator

terminals & listen to the click sound. Repeat this action twice / thrice. If it does

not click remove the actuator from the PT pump / housing & repeat the test. If

the actuator does not click, clean the actuator with clean diesel & repeat the test.

If still the actuator does not click ---- Replace the actuator.

• If the actuator does not click in the housing & if it clicks out side (PT Pump/

housing) then replace the actuator housing / PT Pump -- in case of imported

(Squareness of the housing is not proper).

BASIC FUEL SYSTEM CHECKS:

⇒⇒⇒⇒ Check dust, dirt, and air in fuel system...

⇒⇒⇒⇒ Check diesel level of the tank...

⇒⇒⇒⇒ Check the valves of the tank & fuel supply line for leakage's...

⇒⇒⇒⇒ Are the fuel line sizes as per engine specifications? Check restriction, height of

the return fuel lines. Also check the tank height, tank valves & tank breather.

⇒⇒⇒⇒ Find out when the filter was changed. Is the filter change due now? ...

⇒⇒⇒⇒ Check for loose connections in the supply line (Adapter, Valves, Hose’s “O”

rings etc.) & tighten the connections...

⇒⇒⇒⇒ There are the possible sources of air entry when engine is stand still...

SYMPTOMS & THEIR CAUSES

A list of causes for all the trouble symptoms are given for your ready reference in

this checklist.

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Caution: Please carry out all the checks in given sequence only.

ENGINE CRANKS BUT DOES NOT START.

Causes : ⇒⇒⇒⇒ Battery voltage too low.

⇒⇒⇒⇒ Battery contacts weak / loose.

⇒⇒⇒⇒ Wrong wiring ( In this case if the harness has a loose connection.)

⇒⇒⇒⇒ Starter problem.

⇒⇒⇒⇒ Tank valves closed & filter empty.

⇒⇒⇒⇒ Air lock.

⇒⇒⇒⇒ Improper MPU gap.

⇒⇒⇒⇒ Low idle setting too low.

⇒⇒⇒⇒ Actuator body short.

⇒⇒⇒⇒ Starter pinion not engaging properly.

⇒⇒⇒⇒ Starter key problem.

⇒⇒⇒⇒ Magnetic switch problem.

⇒⇒⇒⇒ Flywheel ring gear broken.

⇒⇒⇒⇒ Actuator sticky in the initial position.

ENGINE NOT TAKING LOAD.

Causes : ⇒⇒⇒⇒ Filter choked.

⇒⇒⇒⇒ Restriction in fuel line / Under sized fuel pipeline.

⇒⇒⇒⇒ Adulteration of diesel.

⇒⇒⇒⇒ Actuator sticky.

⇒⇒⇒⇒ Injector cup choked.

⇒⇒⇒⇒ Air cleaner choked.

⇒⇒⇒⇒ Turbocharger malfunction.

⇒⇒⇒⇒ P.T Pump problem.

⇒⇒⇒⇒ Improper droop setting / droop pot disturbed

⇒⇒⇒⇒ Improper run speed setting.

ENGINE HUNTING

Causes :

⇒⇒⇒⇒ Air in fuel system.

⇒⇒⇒⇒ Water in fuel.

⇒⇒⇒⇒ Fuel filter partially choked.

⇒⇒⇒⇒ Loose connections in fuel lines.

⇒⇒⇒⇒ Restriction in fuel lines.

⇒⇒⇒⇒ P T Pump suction adapter “O” ring damaged.

⇒⇒⇒⇒ Loose connection in wiring / Loose connection in the toggle switch.

⇒⇒⇒⇒ Shielding is not proper.

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⇒⇒⇒⇒ Incorrect wiring.

⇒⇒⇒⇒ Battery voltage too low.

⇒⇒⇒⇒ Incorrect gain setting.

⇒⇒⇒⇒ Droop/ Gain pot damaged.

⇒⇒⇒⇒ Incorrect remote pot.

⇒⇒⇒⇒ Gap between Mag. pick & flywheel ring gear is too large.

⇒⇒⇒⇒ Mag. pick up lock nut loose.

⇒⇒⇒⇒ Dirt / dust on Mag. pick up tip.

⇒⇒⇒⇒ Actuator sticky.

⇒⇒⇒⇒ Actuator springs weak ,rusty.

⇒⇒⇒⇒ Wear marks on actuator shaft.

⇒⇒⇒⇒ Actuator “O” ring damaged.

⇒⇒⇒⇒ Oversize / scored actuator housing.

⇒⇒⇒⇒ Unconnected & hanging wires from mag. pick up to digital RPM indicator.

⇒⇒⇒⇒ A C ripple more than 1.5 v ac.

⇒⇒⇒⇒ Spider coupling in the PT Pump (Loose or Cracked ).

⇒⇒⇒⇒ PT Pump Calibration due / Repairs

⇒⇒⇒⇒ Controller faulty.

⇒⇒⇒⇒ Thyristor load % high.

⇒⇒⇒⇒ Change in load pattern, erratic load, heavy welding load,CNC machine loads etc.

TYPES OF ENGINE HUNTING: --

⇒⇒⇒⇒ Only on low idle.

⇒⇒⇒⇒ Only on high idle.

⇒⇒⇒⇒ On low idle as well as on high idle.

⇒⇒⇒⇒ On load.

⇒⇒⇒⇒ On load above 50 % load.

⇒⇒⇒⇒ On low idle, high idle & load.

⇒⇒⇒⇒ Initial hunting on low idle.

⇒⇒⇒⇒ Engine hunts on load at erratic intervals.

ENGINE STARTS & OPERATES ON LOW IDLE ONLY

Causes: ⇒⇒⇒⇒ Loose wiring.

⇒⇒⇒⇒ Toggle switch short

⇒⇒⇒⇒ Incorrect idle/ run pot setting.

⇒⇒⇒⇒ Actuator stuck up in the initial position.


ENGINE STARTS & OPERATES ON HIGH IDLE ONLY /

OVERSPEEDS.

Causes:

⇒⇒⇒⇒ Wrong wiring.

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⇒⇒⇒⇒ Toggle switch open.

⇒⇒⇒⇒ High idle set too high.

⇒⇒⇒⇒ Remote pot setting too high.

⇒⇒⇒⇒ High throttle Leakage ( worn out actuator shaft).

⇒⇒⇒⇒ Actuator 'o' ring damaged.

⇒⇒⇒⇒ Internal leakage through scored actuator housing.

⇒⇒⇒⇒ Actuator voltage more than 18V.

⇒⇒⇒⇒ Actuator Stud Pin failure. ( In this case engine will overspeed.)


Simple checks for both the above problems :

1.Please disconnect the remote potentiometer before carrying out any troubleshooting.

2. Remove the actuator wires & observe if the engine comes either to

low idle, stops or runs on throttle leakage rpm ( less than the idle ).

3. Remove the toggle switch wires from the controller end. Short link

the toggle switch terminals at the controller, now start the engine.

The engine should start at low idle, if it does start at low idle then

remove the short link when the engine is still running. Now the

engine should go to high idle. This check will determine whether

there is any problem in the toggle switch or not.

4. Now check the controller settings. If these are OK.

5. Then the last stage is to remove the actuator & inspect for Excessive wear

marks, stickiness, 'O' rings, springs ,actuator stud, axial play in the bearing etc.

6. Please note that whenever the actuator is removed from its

housing or the PT pump , it should be thoroughly cleaned as per

procedure already indicated. Also clean the actuator housing.

ENGINE CRANKS BUT DOES NOT START. Have you carried out the basic checks? Yes / No.

Each time you crank check if power OK ,MPU OK LED's glow.(Indigenous

Controller)

Cause Correction

Shut down coil failure Manual override screw (fully clock wise

OR position)

Safety control Failure Check safety controls / replace faulty

safety controls.

Operate the manual screw ( fully

anticlockwise position)

Crank the engine if still engine does not

start check shut down coil replace / shut

down coil.

Air Lock Crank the engine.If it does not start open

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shut down coil plug. Crank & check for

fuel gushing out as soon as fuel comes out,

put back the plug & tighten the same.

No fuel in filter / tank valves closed. If no fuel comes out, check for presence of

fuel in filter / tanks. Check if tank valves

are closed. If still engine does not start,

No MPU signal Crank the engine & check MPU voltage

at cont. terminals ( It should be more

than 1.5 v a.c. If it is less than 1.5 v a.c.

check gap, If gap is ok the replace MPU.

Low idle setting too low. Bring idle pot to it is mid position.

Check act. resistance ---------ohms If act. resistance is not in the range of 7 to

9 ohms. Replace act.

check actuator for body short.

Act. voltage ------------ V d.c. If actuator voltage is less than 8 volt.

Check idle setting ( In case of doubt bring

idle pot to it is mid position ).

Crank the engine. If act. voltage is less than 8-volt replace

controller.

Act, stickiness in initial position. If act. voltage is less than 8 volt & if

engine does not start. Remove, clean &

refit act. as per procedure.

Engine Starts & operates on Low Idle

Have you carried out the basic checks?. Yes / NO

Cause Correction

Toggle Switch short Disconnect the toggle switch from the

controller & check if Engine reaches to

High idle RPM .

13

Idle/ Run setting Keep the idle & run pots at mid position.

Slowly increase the run pot untill H I

RPM is reached.

Actuator stuck up Remove actuator & clean it with. clean

in the initial position . diesel as per procedure given below.

�� Actuator Cleaning Procedure: Remove the actuator from the actuator hsg / PT

Pump. Remove the springs. Remove the allen screws with 5/32" allen key. Take

clean diesel in a clean bucket ( preferably after the filter). Dip the actuator in the

bucket holding the actuator at the base with the actuator shaft dipped in the

diesel. Shake the actuator in this position rigorously for about 2 minutes. Also

clean the springs , allen screws, 'O'rings, sleeve ( in the same manner as the

actuator. Assemble the actuator. Clean the actuator hsg area where the actuator

fits. Refit the actuator on the hsg.

ENGINE STARTS & OPERATES ON HIGH IDLE ONLY / ENGINE

OVERSPEEDS.

Cause Correction

Toggle Switch Open Short terminal No.4 & 5 ( ind.

Controller) & terminal no. 7 & 10 ( imp.

Controller) check if the RPM comes

down to Low idle.

1.Actuator sticky. ( Remove the actuator wires from the

actuator & check if the RPM comes

down or not..) If the actuator is sticky,

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clean the same with* clean diesel (as

per procedure given). Cleaning should

be done after opening the actuator

sleeve

2. Actuator 'O'ring damaged. Replace both the 'O'rings.

3. High throttle leakage Open the sleeve of the actuator & check

for scoring on the actuator shaft. If

scoring is present then actuator has

developed high throttle leakage due to

which the engine may go may go

directly to high idle, which if prolongs

will lead to engine overspeeding

In this case get the diesel sample

checked. Replace the actuator.

4.Actuator stud pin Failure If the actuator retaining stud pin

has failed then engine will over speed.

In this case if the engine has imported

EFC then replace the actuator , EFC

governor (imported with indegenious),

wiring harness,remote pot.

5. Internal leakage through If none of the above has occurred, then

Scored actuator housing replace the actuator hsg & check the

performance.

ENGINE HUNTING :

Have you carried out all basic checks.?.. Yes / No

The steps mentioned below are common to all types of hunting.

∗ Hunting on idle only.

Install fuel sight glass to detect air in the system.( Between P T pump suction

adapter & fuel filter) Start the D.G. on low idle .

Cause Correction

15

Air in fuel Remove air by loosing shunt down

valve plug.

Improper Gain setting Adjust the gain pot.

In case of imported controller Short link A & B & re-adjust gain.

Damaged 'O' rings Remove actuator, inspect ‘O’ rings,

springs, check for stickiness ,clean all

the components & refit as per

procedure. Replace the'O'rings &

springs if damaged as per procedure.

Scored Actuator housing Replace act. hsg.

Controller Faulty Replace the controller & refit the old

Housing & check for hunting.

P T pump calibration /Repair Check for calibration / repairs /

replacement of PT Pump.

ENGINE HUNTS ON LOAD.

Carry out basic checks ( i.e. Wiring & Power Supply Checks , Basic Fuel System

Checks ) before attending to any problem.

The steps mentioned below are common to all types of hunting.

Install fuel sight glass to detect air in the system.( Between P T pump suction

adapter & fuel filter) Start the D.G. on low idle .

Cause Correction

Air in system Remove air

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Sequential operation of Loads Readjust gain pot & confirm.

( is the sequence altered ? )

For imported controller put short link between A & B terminals. & check if engine

hunts.

LOAD CHARECTERISTICS

Check for thyristor load. In case of such problems , thyristor load plays major role.

Alternator Voltage Fluctuation Refer alternator manual to arrest/

Troubleshoot alternator problems.

Al.ternator voltage Fluctuation First arrest the speed hunting then

due to Engine speed hunting. arrest the alternator hunting if

necessary.

Thyristor Load % High. Check if the machine is derated

appropriately to achieve The desired

load. ( refer Respective alternator

Manual for deratings on thyristor

load).

ENGINE NOT TAKING LOAD.

Causes :

⇒ Filter choked.

⇒ Restriction in fuel line / Under sized fuel pipeline.

⇒ Adulteration of diesel.

⇒ Actuator sticky.

⇒ Injector cup choked.

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⇒ Air cleaner choked.

⇒ Turbocharger malfunction.

⇒ P.T Pump problem.

⇒ Improper droop setting / droop pot disturbed.

( For ex. If run speed is adjusted to 1500 rpm & droop pot is in fully

clockwise position. i.e. 6% droop then the speed would droop down drastically

on load.

Warning !!

IN THE PROBLEM OF ENGINE NOT TAKING LOAD

CONTROLLER FAILURE IS NOT THE CAUSE !!!!!!!!

Actuator problem to be attended to only after solving all engine related problems.

Remove actuator , clean & refit as per procedure.

Cummins EFC Troubleshooting Guide

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Transcript of Cummins EFC Troubleshooting Guide