GTi6 fuel pump probs
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  1. #1
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs

    Hi all,
    Started the 6 this arvo, trundled part way down my driveway and then had to answer my ringing phone. After sitting idling for no longer than 30 secs she just died. Went to start her again, waiting for the pump prime to almost end before giving it another go, but the fuel pump kept running continuously (rather than the usual short hum) and she refused to start.
    Turned it right off and then gave it another go but no fuel pump prime was heard and the diagnostic light is on. Have tried many times since but no prime.
    Could the relay be at fault here? Why was the pump running continuously and now nothing?
    Have tried disconnecting battery to reset ECU and clear any potential faults to no avail.

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  2. #2
    Fellow Frogger! Bluey's Avatar
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    Check Fuses, particularly anything fuel and ecu related.

    Check fuel pump relay, i.e. remove it and put power and earth to the 85 & 86 signal pins. It should 'click' and there should be continuity between the 30 & 87pins.
    I think there might be 2 relays you have to check, one pump specific and another....? Not sure.

    Check that the fuel pump relay signal pins in the plug (85 or 86) are actually getting signal to turn the pump on when the ignition is turned on. If they don't then it's wiring or ecu related which would explain the fault light.

    Remove back seat to access pump cover.
    Disconnect the plug and check if the pump is getting power at the plug when the ignition is switched on (use test light).

    If yes, hot-wire/jump the pump and check that there is fuel flowing to the rail.
    If yes, test fuel pressure.
    If in spec. test current draw at pump. If it's near the limit of the fuel pump fuse then it needs replacing. Usually anything more than 12A is a sign it needs replacing.

    If it isn't a fuel pump related issue start looking for ECU related faults i.e. relays, melted plugs shorting pins etc.
    Last edited by Bluey; 16th November 2012 at 09:06 PM.

  3. #3
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs

    Cheers Bluey. Will post results.

  4. #4
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs

    TBH Bluey I'm not super proficient with electrics. The numbers on the plug and relay run from 1-15 so I followed this diagram...
    Attachment 36576
    ...and the pump ran with no diagnostic light showing so I gather it's the relay at fault?

  5. #5
    Fellow Frogger! Bluey's Avatar
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    Can't load the link.

  6. #6
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs


  7. #7
    Fellow Frogger! Bluey's Avatar
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    I can't see the images because I'm not a member but the process described sounds good.

    I'm presuming 5 & 8 pins are the high current side. I would check for continuity between one of those two pins and the plug at the pump just to make sure that either of those wires are the direct line to the pump and not just a signal to a 2nd relay.

    The measuring of resistances on the relay itself will be testing whether the low current side of the relay is functional and should tell you if it's broken or not.

    In theory you should be able to power up the two pins used for each resistance test and it should, A: click and, B:give you continuity between the 5 & 8 pins on the relay. If it does give continuity it won't be the relay.
    Probably the easiest way to test this is to plug the relay into the loom and back-probe the 5 & 8 wires for a continuity test with someone switching on the ignition for you.

    Last thing I would check is that the relay is getting signal to the low current side of the relay. Whichever pins are used to test the resistance, one of the two corresponding pins in the plug should have power when the ignition is initially switched on.

    If that all checks out then i think you can safely say it's the relay. I don't think there's anything else left to cover.

  8. #8
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs

    Thanks Bluey.

  9. #9
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs

    Swapped the relay to be sure and still no action. Starting to think it may be the ECU.

  10. #10
    Fellow Frogger! zac505's Avatar
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    Default GTi6 fuel pump probs

    ...or a bad earth somewhere...

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