Mk2 gti wont start

Discussion in 'Mk2' started by Davec30, Oct 8, 2017.

  1. Davec30 New Member

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    Help my mk2 gti wont start but will run if put relay 18 instead of relay 80 for fuel pump
     
  2. Tristan

    Tristan Paid Member Paid Member

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    Try another fuel pump relay so?
     
  3. Davec30 New Member

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    Yes go two 80 relays still nothing
     
  4. notenoughtime

    notenoughtime Moderator Moderator

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    Bypass the relay i.e. Bridge the feed to the pump and see if it starts
     
  5. Davec30 New Member

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    Done that with relay 18 instead of 80 and it runs so whats problem
     
  6. notenoughtime

    notenoughtime Moderator Moderator

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    Is there power to switch the relay?
     
  7. Davec30 New Member

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    Aint got a clue mate hate wiring. Can hear clicking with ignition. Just dont get how it will run with relay 18 instead of 80.
     
  8. Tristan

    Tristan Paid Member Paid Member

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    Because 18 hasn't the timer in it, and doesn't need all the switching wires that 80 does. If you look it has more pins, notably small ones at the corner.
     
  9. Davec30 New Member

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    Yes 18 only has 4 pins. So what think problem could be as another 80 still doesnt work :(
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    Does the pump prime on ignition? If not and the if the car runs perfectly with the 18 relay in can be pretty sure its the switched earth trigger for the relay from the ecu. look in the engine bay under the scuttle tray, it'll either have a couple 2 pin spade plugs on the left side if its CE1 or a 5 pin timer plug clipped next to the ecu if its CE2.

    Make sure pins clean and tight, the one you're looking at specifically is the red/yellow. with the 80 relay (67 or 167 will work too) inserted and ignition on if you push an earth wire into the fusebox side of this connector the fuel pump should run.

    If it does prime check you get 12v to the green/red wire while cranking, iirc someone found the pump wouldnt trigger till this feed was fixed. On CE1 its fed from a spade plug on C/18 behind the fusebox, on CE2 it runs straight to F/5
     
  11. Davec30 New Member

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    It only primes if relay 18 is in like its jumped. Will not prime with relay 80
     
  12. rubjonny

    rubjonny Administrator Staff Member Admin

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    righto look at the ecu trigger wire :) G1/3 if CE2, D/13 if CE1
     
  13. realcaz New Member

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    I have had a long losing battle with this issue. With relay 67 in & car switched on, the pump only works when I ground G1/3 @engine bay under tray. ECU just wont ground it. I have checked all connectors and contacts under tray and they're all clean. Last resort is running continuity check on the wire from plug to ECU connector. . .??:idea:
    If all fails I'm calling it a day:
    [​IMG]
     
  14. Davec30 New Member

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    Swap my ecu for another and pump works again on mine
     
  15. realcaz New Member

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    Do you have any Idea what the cause is? It would be awful to have to replace it more than once.
     
  16. Davec30 New Member

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    Not really probably bad earth or dry joint or something. Rubjohnny probably know more
     
  17. rubjonny

    rubjonny Administrator Staff Member Admin

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    if the car starts and runs fine like this, then all it can be is the ecu or a problem on the relay trigger wire between it and the fusebox. Rather than buying a new ECU you can get a kjet 8v fuel relay instead, this is triggered from the rev counter feed so its safe if you crash. Get the type without a rev limiter inside, that way the ecu will still take care of that side of things: (relay number, vw part number, kracker part number, GSF part number)
    2 = 443906059A/321906059D/E = no limiter (superceeded by 321906059F)
    3 = 443906059 = no limiter (superceeded by 321906059E/F)
    63 = 321906059F / 24.1400.20 / 935VG0090 = no limiter
     
  18. Scotty mk2 golf New Member

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    Hi buddy sorry to bring up an old subject I'm having a very similar issue to the subject above! I've tried a Hella relay with the F VW part number and it isn't operating the fuel pumps at all. I'm just wondering if it's plug and play or do I have to fettle any wiring to get it to work. I just want to eliminate the trigger wire as I've replaced both pumps and relays and fuse box. I've had this problem for nearly 2 years now and I think I've solved it and then boom without warning here we go again‍♂️ every time I get the multimeter out it then starts to run as normal again
     
  19. Scotty mk2 golf New Member

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    All sorted, ended up being a fuse with a dodgy terminal. Was getting a live at every point up until the fuel pump wiring out the back of the fuse box. Pulled the fuse out and swapped it with another, then hey presto ITS ALIVE AGAIN
     
  20. rubjonny

    rubjonny Administrator Staff Member Admin

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    might need a new fusebox if the fuse socket is getting loose, can always split it to see if its repairable :)
     

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