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Fuel pump?

Discussion in 'A4/S4 forum(B5 Chassis)' started by Foxmeister, Feb 15, 2011.

  1. Foxmeister
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    Foxmeister Fired Up!

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    Think its packed up, last time i ran the car it was low on petrol and started hunting a bit and sounded rough, like it was ready to chuck it, eventually did. Left it as i was busy doing things and was going to shops later and took tank for juice.

    After filling it and trying to start its just kicking over, when planting the accelerator i can hear a faint combustion from the exhaust. Also, last time it was running as described above, i could hear the hum from the fuel pump really loud, which it never done before!

    Unforunately i still havent sorted out Vagcom yet so the old fashioned way it is. Im sure ive seen RS4's etc with the pump accessed from inside the car, by lifting the back seat up, is this the case with all A4's? Mines a saloon 97.
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  2. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    yes back seat remove
    access panel under there
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  3. Foxmeister
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    Foxmeister Fired Up!

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    Thanks mate, thats my Fri afternoon filled then!
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Short out the fuel relay and see if the pump runs, and check the fuse too.

    Theres an access hatch right at the back of the boot (or behind the offside rear seat) on Quattros
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  5. Foxmeister
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    Foxmeister Fired Up!

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    Will do mate, first port of call is the relay etc.

    Didnt get it done today so will have a look at it tomorrow. Cheers.
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  6. Foxmeister
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    Foxmeister Fired Up!

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    Lazy b*$tard, i know, thats me just getting round to this!

    Anyway, for quickness, does anybody know relay no etc and what the connections are to short out of hand?
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  7. Foxmeister
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    Foxmeister Fired Up!

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    Okay, working with relay no 372 i shorted out terminals 30-87 to bring on the pump permanent. No starting still, although can smell petrol strongly.

    Then accessed the fuel pressure regulator, removed this to find petrol(car has stood for weeks) so this seems to show fuel pump is working as normal? Saying that, if the relay is proper gubbed, it may be the injector side or something that is faulty and still failing to start. Any other ideas of ruling out any other components or will just take the plunge and order a new relay to see if that sorts it?

    Any help asap appreciated as the car is now abandoned down the drive and will be almost impossible to shove back to garage!
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    The fuel pump relay should be the fourth relay on the lower relay carrier.

    It should have 30, 87F, 87a, 15 and "S"

    As far as i can see 87F is the fuel pump, and 87a is the injectors etc. They'll both need power for the engine to start.

    Simply looking in the pressure regulator wont tell you anything. Try powering the pump with the regulator removed to see if you get fuel pouring out.
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  9. Foxmeister
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    Foxmeister Fired Up!

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    Its too dark now but managed to re-do the relay with the fuel injectors linked aswell, no joy! Didnt get a chance to check if petrol is being pumped yet, will continue tomorrow.

    Also, whats best way to check for a spark on these cars??? Also, ignition modules a common fault with these incase thats worth looking at?
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  10. Foxmeister
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    Foxmeister Fired Up!

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    Quick thought, after having a search i found this thread on it

    Audi A4 will not start

    Similar symptoms i have been having, including when previous to this my car would start then cut out via immobiliser due to reader coil or whatever that i never got round to looking at. Car also has been stood long periods of time with flat battery, could it be that my key and ecu arent connecting to multiple flat batteries and will need re-coded via Vagcom???
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    If its immo related the immo light would be flashing, and the car usually starts then cuts out after a few seconds.

    Does your immo light go off as expected if you just turn the ignition on and dont try to start?
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  12. Foxmeister
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    Foxmeister Fired Up!

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    It doesnt stay on mate.

    Just been back out at it, stuck the jump leads on and decided to have a listen for the fuel pump, which i heard straight away before i even got the key in the ignition....id left the relay linked out from last night! Doh!

    Quickly disconnected the jump leads and removed the relay and put it back to normal, but the fuel pump mustve ran at least a good 10secs and i could here a lot of air being pushed thru. So re-connected the leads and had a try at starting it before anything else, f*$ker started first time!

    Must be air in fuel lines from car lying so long with flat battery and low petrol levels i assume, or the pump is on its way out and its intermittent at the moment, either way im glad its back in the garage and i'll be going for a new battery this weekend and my Vagcom cable will be thru by then, but hopefully i'll no see this problem again.

    Thanks for input guys, especially Kev for keeping the ideas coming, appreciate it.
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  13. karls s3
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    karls s3 Member

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    where is the fuel pump relay.
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  14. Foxmeister
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    Foxmeister Fired Up!

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    Its under the drivers knee panel, have to remove the lower section of dash. As you look at front of the car, its the very right hand side relay, no 372.
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  15. NineNails
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    NineNails Proud sponsor of the snack food industry

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    4x 8mm bolts. 2 are behind fuse board cover.
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