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Thread: Frequency Valve and Fuel Pump not shutting off

  1. #1
    Senior Member AugustneverEnds's Avatar
    Join Date:  Jul 2012

    Location:  Syracuse, NY area

    Posts:    811

    My VIN:    SCEDT26T5CD010287

    Club(s):   (DMA)

    Frequency Valve and Fuel Pump not shutting off

    So like the title says I switch the ignition off but those two keep running. I pulled fuse 7 to stop them. Any ideas where I should be checking first? Thanks as always gang
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12

  2. #2
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    7,325

    My VIN:    03572

    RPM relay if stuck on will do that.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #3
    Senior Member AugustneverEnds's Avatar
    Join Date:  Jul 2012

    Location:  Syracuse, NY area

    Posts:    811

    My VIN:    SCEDT26T5CD010287

    Club(s):   (DMA)

    Simple enough to check. I think I have an extra one laying around. I'll swap 'em and see what happens.
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12

  4. #4
    Senior Member AugustneverEnds's Avatar
    Join Date:  Jul 2012

    Location:  Syracuse, NY area

    Posts:    811

    My VIN:    SCEDT26T5CD010287

    Club(s):   (DMA)

    So I plugged in the extra RPM relay and the pump and FV are turning off with the ignition. There is a difference between the old RPM relay and the newer one I installed, the FV buzzed all the time with the old one and now it does not when the key is in position 2. The car starts fine either way and the FV started buzzing when the engine was running. Are there two varieties of RPM relays out there? The original one in my car is probably the one it left the factory with. The replacement came with the DMCH relay update kit.
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12

  5. #5
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    7,325

    My VIN:    03572

    The original relay had two contacts on the relay and sometimes the contacts would not both mate. I've seen a few NOS relays never power the lambda (FV). I've not seen any core returns have stuck contacts but the relay pins mostly break the solder joints and then the pins can move.

    Now most of the RPM relays use one contact and therefor both the pump and lambda either work or not.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  6. #6
    Senior Member
    Join Date:  Aug 2018

    Location:  Virginia

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    My VIN:    1623

    I highly recommend bitsyncmasterís RPM relay. Itís light years ahead of both the factory and Bosch replacement relays. As youíve seen, itís a critical part of the car.
    DMCF rebuild 2008, Stage II, Eibach

  7. #7
    Senior Member AugustneverEnds's Avatar
    Join Date:  Jul 2012

    Location:  Syracuse, NY area

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    My VIN:    SCEDT26T5CD010287

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    Quote Originally Posted by CFI View Post
    I highly recommend bitsyncmasterís RPM relay. Itís light years ahead of both the factory and Bosch replacement relays. As youíve seen, itís a critical part of the car.
    Every time my car does something like this I am amazed it has covered as many miles as it has and as, relatively for a D, reliably as it has. I really do need to ditch the antiquated relays and buy Mr. Dave's.
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12

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