Author Topic: understanding the mk3 fuel system  (Read 2448 times)

Offline gofasterpinch

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understanding the mk3 fuel system
« on: April 08, 2012, 12:36:00 pm »
this week discovered fuel dripping heavily from the filter region while cranking the car over, basically the few standard hoses that are left are completely perished before/after the filter, which im in the process of replacing with aeroquip/goodridge. the cars been in storage since 09 and i had began wondering where the fuel was disappearing to!

question is: whats the deal with the 3 fuel line system on the mk3? black/blue/blue? and then theres that plastic box before the inline pump/filter assembly, which i assume is some sort of swirl pot that takes in the fuel from the throttle body return? just trying to clarify exactly how the system works before i start purchasing new lines to sort it!


Offline djtez

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Re: understanding the mk3 fuel system
« Reply #1 on: April 08, 2012, 01:42:46 pm »
The white box am sure is an accumulator

Three hoses.. Do not remember colouring but

1. Engine feed
2. Fuel return
3. Tank breather which am sure is connected to charcoal canister??

Mine is blocked off and canister removed

Offline gofasterpinch

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Re: understanding the mk3 fuel system
« Reply #2 on: April 08, 2012, 04:26:55 pm »
i have already removed the breather, there are still 3 lines left.

the black fuel line goes Accumulator>fuel pump>filter>throttle body, then one of the blue lines is the return from the throttle body, but whats the 3rd?

Offline djtez

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Re: understanding the mk3 fuel system
« Reply #3 on: April 08, 2012, 04:30:47 pm »
Still think am correct sayin the charcoal canister..

The 3rd line has likely not been removed.

Look lower left of engine bay directly below servo and you'll see the three lines clipped to the chassis, just follow then up to get a definet result

Offline gofasterpinch

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Re: understanding the mk3 fuel system
« Reply #4 on: April 08, 2012, 04:53:00 pm »
you still think you're correct? why, did you build my car?

there is definitely no charcoal canister, or line running under the car. i removed it myself about 8yrs ago and shortened the -8 rubber hose that sits inside the drivers side wheel arch.

there is still, 2 blue lines and the black one which all go into the accumulator

Offline djtez

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Re: understanding the mk3 fuel system
« Reply #5 on: April 08, 2012, 05:03:47 pm »
Good luck with getting help

Offline gofasterpinch

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Re: understanding the mk3 fuel system
« Reply #6 on: April 08, 2012, 05:15:37 pm »
sorry, but i just don't see how you can justify your assumptions?  :-\

the clips running under the drivers side carry 4 lines, 2 black 2 blue, the charcoal canister takes a further black line.

Offline djtez

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Re: understanding the mk3 fuel system
« Reply #7 on: April 08, 2012, 05:33:02 pm »
Ok
I'm only trying to spit ball to try help...

Part of the reason this forum exists!

No one person can be right at everything....

A cant even remember the last time a looked under the g40 but I only remember 3 lines, 4th possibly another breather .

Try searching on clubpolo

Offline pettsy

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Re: understanding the mk3 fuel system
« Reply #8 on: April 09, 2012, 01:22:35 pm »
have to say i thought there were only 3 under the car, flow,return and breather  ???

Offline Yoof

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Re: understanding the mk3 fuel system
« Reply #9 on: April 09, 2012, 03:08:34 pm »
have to say i thought there were only 3 under the car, flow,return and breather  ???

I agree

Offline Jezza-7

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Re: understanding the mk3 fuel system
« Reply #10 on: April 09, 2012, 04:03:26 pm »
Yep agree too!

A haynes manual will tell you so best get one. I could go look at mine but i cant be bothered.

Offline djtez

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Re: understanding the mk3 fuel system
« Reply #11 on: April 09, 2012, 04:11:19 pm »
lol

Offline Nick_S

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Re: understanding the mk3 fuel system
« Reply #12 on: April 10, 2012, 12:14:50 am »
I seem to remember the slightly narrower one being the breather pipe to the charcoal cannister.

Offline gofasterpinch

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Re: understanding the mk3 fuel system
« Reply #13 on: April 10, 2012, 09:59:50 am »
ok just to save confusion  :D

there are 4 lines that come off the bracket with the accumulator/filter/pump but only 2 of which go to the engine bay on mine (charcoal canister removed which would be 3 running under the car originally)

one comes off the filter and feeds the throttle body, but where do the 3 off the accumulator go they disappear just the other side of the axel and i assume are involved in the tank/lift pump assembly?

Offline Yoof

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Re: understanding the mk3 fuel system
« Reply #14 on: April 10, 2012, 01:48:52 pm »
Say sorry to Terry and I'll tell you  :P