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Thread: 500E fuel pump runs without key.

  1. #1
    Senior Member Jord's Avatar
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    500E fuel pump runs without key.

    1992 500E as stated in the title the fuel pump will run when ever it wants. It usually runs for 2 minutes after you shut off the car. After that it will continuously turn on and off literally hundreds of times till the battery is flat. Usually after a day and a half the battery is done, now it's only a day as the battery is taking a beating through all this. I have swapped the ecu which made no changes, and I haven't changed the relay YET. Any ideas in case the relay isnt the issue?

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  3. #2
    .036 Hoonigan™
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    gsxr's Avatar
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    Re: 500E fuel pump runs without key.

    Jord, this could be an LH module failing, but I seriously doubt it - and since you swapped it already, I think it's safe to rule that out. A sticking relay is also very unlikely, but easy to swap out (under rear passenger seat cushion).

    However, it does sound a lot like what can happen when the 38-pin connector gets internal corrosion. Full details at this link:
    https://www.500eboard.com/forums/showthread.php?t=10073

    Check that X11/4 connector closely! If the pumps are running with the key off, try pulling the BM/GM and see if the pumps stop.

    Dave M.
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    JC220 (2 Weeks Ago), Jord (2 Weeks Ago), TerryA (2 Weeks Ago)

  5. #3
    Senior Member Jord's Avatar
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    Re: 500E fuel pump runs without key.

    Quote Originally Posted by gsxr View Post
    Jord, this could be an LH module failing, but I seriously doubt it - and since you swapped it already, I think it's safe to rule that out. A sticking relay is also very unlikely, but easy to swap out (under rear passenger seat cushion).

    However, it does sound a lot like what can happen when the 38-pin connector gets internal corrosion. Full details at this link:
    https://www.500eboard.com/forums/showthread.php?t=10073

    Check that X11/4 connector closely! If the pumps are running with the key off, try pulling the BM/GM and see if the pumps stop.
    Thank you. I'll try to set it up for failure and see if I can find it.

    Sent from my SM-N950U using Tapatalk

  6. The Following User Says Thank You to Jord For This Useful Post:

    TerryA (2 Weeks Ago)

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