ABF fuel pump query

Discussion in 'Engines' started by lmn, Jun 29, 2020.

  1. LMN

    lmn New Member

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    Ok I think the fuel system should be all ok in that case.

    Issue must be electronic. Given that the car was running fine a few months ago, is this likely to be an immobiliser issue, is it an issue that can suddenly appear over night?

    Are there any quick checks I can do, like checking/replacing relays, testing wires, etc... Anything simple or cheap that I can try before going onto more severe troubleshooting?

    Thanks for all the help so far really appreciated!! Already saved me money and time on parts that are not needed with my setup :)
     
  2. Savagesam

    Savagesam Moderator Staff Member Moderator

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    Oh okay, the way the post was written was like it’d not been ran!

    Had the ECU been deimmo’d or is it hiding the ring and chip somewhere? (Someone bodged my old car like this)

    or it may not have one, depends on the year.

    check the wiring and relays anyways, won’t do you any harm.
     
  3. LMN

    lmn New Member

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    I'm pretty certain it has an immobiliser, not sure if its aftermarket though. Would it be worth getting the number off the ECU, can that tell us anything useful?

    And what is the best method for testing relays/wires? Do I basically just want to confirm that the pump is getting constant power? Is it worth bridging the relays before buying new ones or is that bad for the wiring?

    Thanks!
     
  4. rubjonny

    rubjonny Administrator Staff Member Admin

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    if its the factory immobiliser the car will start and run for a couple seconds then cut out so its possible. also if you scan the ecu with vagcom it'll flag a code for immobiliser, then you scan immobiliser box and it will tell you why its kicking in.

    get yourself a usb vagcom cable and get it plugged in, apart from the above can check for any other codes and also scan through all the ecu measuring blocks to see sensor inputs in real time. first one I'd check is engine speed, if it doesnt go up while cranking then your crank sensor is duff.

    get these installed as well:
    https://clubgti.com/forums/index.php?threads/vag-com-abf-digifant-label-files.199583/
     
  5. LMN

    lmn New Member

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    Awesome, thanks!

    There looks to be a lot of cables out there, any recommendations? Just enough for what I'm needing for the mo, unless it's worth investing a bit more for the future.
     
  6. LMN

    lmn New Member

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    Scratch that, seems my mechanic has a proper VW one. But no port apparently. Is it likely to be hiding somewhere, or will we have to install one?

    Thanks!
     
  7. rubjonny

    rubjonny Administrator Staff Member Admin

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    the guy who did the sawap would have to install it, so often forgotten. look for a grey/white wire floating around loose. if it has the immobiliser box fitted the wire for the port hangs off that, if not its from ecu loom
     
  8. LMN

    lmn New Member

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    Hi,

    Just to update:

    I didn't get around to installing a diagnostics port in the end, but may do so in the future as it seems like it'd be very useful.

    The issue in the end was a faulty wire connecting to the immobiliser box. Now that it has been reconnected, the car starts up just fine. However, once every so often, the car won't start at all. For now, the immobiliser has been repositioned outside the dashboard next to the steering wheel. So when it doesn't start, I just unplug and replug the wire into the immobiliser box.

    This works ok for now, I might look to get a new immobiliser at some point.

    Thanks again for everyone's help!
     
    Savagesam likes this.
  9. Savagesam

    Savagesam Moderator Staff Member Moderator

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    Good to hear. Definitely get the OBD port installed. it’s only 3 or 4 wires.

    I’d remove it all together personally.
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    once thats installed you can check the immo box codes, sometimes its the reader coil and sometimes its the box itself which fails. to replace it you'll need to use a registered copy of vagcom/vcds so be sure you get the port wired in first ;)
     

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