ABF fuel pump query

Discussion in 'Engines' started by lmn, Jun 29, 2020 at 10:36 PM.

  1. LMN

    lmn New Member

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    Hi all,

    Just made an account as I've got myself quite confused.

    I've had a look around the forums to see if I could find an answer but gave up so sorry if this information is already out there.

    I have a mk2 golf with a mk3 ABF installed. I haven't been able to get it started for a month or so now. Turning the ignition will start the engine for a very brief moment before it cuts out again.

    Figured this was down to a poor fuel pump (made sense to me that the lift pump would give the engine the fuel to start and the main pump would never kick in). So I replaced the in tank pump thinking this was the main pump and was still getting the same issue.

    Now I come to find that there is no external fuel pump on my car. Looking in the Haynes manual, I can see there should be an external pump under the car, mine is completely missing.

    Before I go ahead and buy an external pump, I just want to make sure that this would be the right thing to do. I'm now wondering if mk3 ABFs only have a one pump system? If so, what are some other areas I can troubleshoot?

    Thanks,
    lmn
     
  2. Savagesam

    Savagesam Moderator Moderator

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    To me that sounds like the ecu is still immobilised.
     
  3. LMN

    lmn New Member

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    Thanks for the fast reply!

    It's with my mechanic at the moment, he said previously that he's eliminated the immobiliser. Is there a test specific for this that I can go back to him with?

    Thanks!
     
  4. LMN

    lmn New Member

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    Before I go ahead and start buying more parts, is anyone please able to confirm if I need the external pump for my ABF setup?

    Should it be lift pump > reservoir > external pump > filter > engine, or is it a different structure?

    Unless my external pump was stolen/fell off since the last time I drove it, it has been running just on the lift pump alone, so maybe that is the setup needed for ABF, or maybe it can run but isn't good for the pump?

    Any info would be very helpful,
    Thanks!
     
  5. rubjonny

    rubjonny Administrator Admin

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    mk2 golf shuld have a pump in the tank and one under the car, but a mk3 golf just has the one in the tank. post a pic of the fuel pump in the tank?
     
  6. LMN

    lmn New Member

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  7. rubjonny

    rubjonny Administrator Admin

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    yep thats a mk3 pump, so as long as the replacement was for a 2.0 8v/16v or VR6 you're fine
     
  8. LMN

    lmn New Member

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    Ah ok, the replacement I found is the exact same I'm pretty sure.

    So I don't need an external pump and filter setup in addition to this? It should just be the one in-tank pump is all that is needed and the issue lies elsewhere?

    Thanks!
     
  9. rubjonny

    rubjonny Administrator Admin

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    there should be a fuel filter under the car, the mk3 has a little bracket which fits straight up to 2 of the mk2 fuel pump studs. if its not there you'll definitely want to fit one. any petrol mk3 will do as a donor
     
  10. LMN

    lmn New Member

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    Ah ok!

    This is the picture I'm working from:

    https://i.imgur.com/4UUpuM6.jpg

    I'll ask my mechanic if there is a filter underneath, if not, should I be getting a specific mk2/mk3 filter?

    Thanks!
     
  11. Savagesam

    Savagesam Moderator Moderator

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    That’s a mk2 golf under car pump/filter.
    You don’t need that with the Mk3 tank
     
  12. LMN

    lmn New Member

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    So at some point the fuel circuit reaches down underneath to go through the fuel filter?
     
  13. LMN

    lmn New Member

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    Assuming all is eventually well with the filter, you think my starting problem is most likely to be caused by an immobilised ECU?

    Thanks!
     
  14. Savagesam

    Savagesam Moderator Moderator

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    You’ll have two lines, Both go under the car, one goes through a filter, the other is the return and both will appear in the engine bay.
     
  15. LMN

    lmn New Member

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    ok thanks!

    Looks like the filter is all ok underneath the car, so I that's all fine I think.

    What can I do about this immobilised ECU, or should I make a new thread?
     
  16. LMN

    lmn New Member

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    Another issue:

    It seems like the wiring may still be set up for the old mk2 engine, in that it may still be treating this new mk3 pump as the lift pump. How can I change this, new wiring loom needed or relay?

    Thanks!
     
  17. Savagesam

    Savagesam Moderator Moderator

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    If it’s got a Mk3 tank, I hope whoever fitted it, also swapped the Mk3 loom over too. The plug is different so if post post a picture someone should be able to identify it
     
  18. Savagesam

    Savagesam Moderator Moderator

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    Have a look through the engine section, or the search bar. I know the ABF isn’t the easiest to deimmo. But I’m fairly sure, VCDS will be able to tell you if it’s still active.
     
  19. LMN

    lmn New Member

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    I'll get my mechanic to send a photo tomorrow hopefully.

    Would the mk2 loom not be compatible with the mk3 pump? Because it has run just fine in the past with a mk3 pump, so assuming maybe they did swap the loom?
     
  20. rubjonny

    rubjonny Administrator Admin

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    the mk2 lift pump plug wont fit a mk3 pump so its been adapted at the same time

    this is what the mk3 filter carrier looks like, or the earlier one is a simple metal bracket and filter is jubilee clipped to it. you use mk3 golf fuel filter but its same part number as mk2 digifant one
    jetta-tdi-fuel-filter-replacement-wiring-library.jpg
     

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