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Fuel

Filter

housing

construction

and

flow

paths,

CJAA,

CBEA,

Early

BRM.

Thisistheonewiththewaterremovalscrewontop.

Ihavealwayswonderedhowthefuelflowedthroughthishousing,andrecently

hadachancetofindout.

1.

Ihavelabeledthepassagesinthistextwithnumbersandusedcolored

cabletiestohelpmakethepassagesclear.

2. Thisparticularhousingcameoffofa2010CJAAJetta.

3.

Aswith

many

apparently

simple

automotive

components

there

are

quite

a

fewimportantdesignfeaturesincorporated.Iwillpointsomeout,but

therearelikelysomethatImissedaswell.

4. Notethetampersealwaxontheventscrewandoneofthefiltertop

screws.

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Flowpathsandimportantfeatures.

1) (RED)Fuelentersfromtheliftpumpandisdumpedoutsidethefilter.Fuel

isfreetoflowaroundtheouteredges,andthetopandbottomofthefilter

housing.

2)

(Yellow)Thisisthefuelreturnlinetothetank.

3) (Green)Thisscrewsealsthetopofatubethatrunstotheverybottomof

thefilterhousing. Itisonlyopenatthisscrewandontheverybottom.

4) (Yellow)Thisisthereturnflowfromtheengine(fromfuelrailandHPFP

excessontheCJAAandCBEA,fromthereturnfuelrailbuiltintothehead

ontheBRM.)Thisiswherewearparticlestravel.

5)

(White)Thisiscleanfueltotheengine(viatheboosterpumpandHPFPon

theCJAA

and

CBEA,

and

to

the

tandem

pump

on

the

BRM.)

6) (Yellow)Thisgapinthetopislabeledbecausethereisanopenpassagein

thecenterfueldistributionassemblyunderthislid.

7)

(Notnumbered)Twodetentsforaligningtheheadandcenterfuel

assemblytoeachother,locatednearthecenterofthelid.

8) (Notnumbered)Adetentontheedgetoalignthelidtothebodyofthe

filterhousing.

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Showingflowdirectionandusingcolorstoshowjoiningflowpaths.Path1inthe

lowerrightiswherethefuelentersandshouldbeshownasred. (Inactualityit

hasared

and

yellow

tie

in

it;

Iwish

the

red

was

on

topThe

yellow

recirc

flow

pathjoinsthereddirtyfuelflowpaththroughthechannelmarked6here.

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Thisshowsthebottomhalfofthecentralpostassemblythatinsertsintothe

toppiece. Notethetubeandoringforthewaterremovalpassage. Notethe

sideviewofthefalsefloor,whichcreatesthebottomtraporplenum.

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Thisisthebottomofthecenterpostassembly.Thehighpipewiththeoringseals

totheupperhalfofthehousing,providingasealedtubeallthewaythroughthe

centerhousingtotheunfilteredfuelareabelowthefilter. Notetheslotsaround

thebottomflangeforthetopsclipstomateinto.

Notethefalsefloorthathasanareacutouttoallowwaterandsedimenttofall

intotheclosedplenumbelowthefalsefloor. Theonlywayto getthewaterout

ofthisareaistoturntheassemblyupsidedownafterremovingthefilter.

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Thisshowsthetopandbottomofthecenterpostsetontopofeachother,but

notclipped. Notethegreentieofthewaterremovalportstickingoutthe

bottom.

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Thisshowsthebottomoftheassembliessetoneachother.Thebottomclips

mateintoslotsonthebottomofthecanister. Theouterspringismissinginthis

photo.

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Thisphotoshowsthetopandbottomalmostcompletelymated(notetheoringis

stillslightlyvisiblethetopneedstoslidedownanothereighthofaninch. Both

springsarevisibleinthisphoto.

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AviewwiththeOlympicringsinplace. Notethathereyoucanseethattherecirc

flowpath(yellow)joinstheredintherectangularnotchshownonthelowerarcof

thetop. Recircflowisfreetomixwiththeunfilteredfuelaroundthetop,outside,

andbottomofthefilter. Thisiswherethemetalparticlesenterthetopareaof

theassemblyinthosedramaticphotosofHighPressureFuelPumpdamage.

The

recirc

flow

through

the

ports

marked

in

yellow

are

what

VW

calls

the

fuel

heater.

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AphotoofacutupOEMfuelhousing. Notetheflangetackweldedonthe

bottomthatthecenterassemblyclipsinto. Alsonotethepassagesthatallowfree

flowoffuelandwaterintothecentralarea.