Fuel pump not working

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  • tnicholls
    Noobie
    • Aug 2013
    • 21

    #1

    Fuel pump not working

    Hi everyone my fuel pump is not priming or running on my m50. just put the motor back in from a rebuild. I have changed the ecu, fuel pump relay and checked grounds and I'm at a loss. The fuel pump kicks on if you bridge the relay with a piece of wire. any ideas?
  • Sea Aych
    Mod Crazy
    • Apr 2013
    • 763

    #2
    Are you sure the relay isn't busted? Swap in a new one.
    1988 Atlantisblau Euro/Japanese 325i Cabriolet
    1989 Schwartz 325i - now M50 powered! - now very dead
    1998 Toyota 4Runner Limited
    My 17,000km Big NA National Parks trip!

    Comment

    • tnicholls
      Noobie
      • Aug 2013
      • 21

      #3
      tried that and switching ecus and nothing

      Comment

      • greybeard
        Noobie
        • Mar 2017
        • 6

        #4
        try testing your crank position sensor. I was having the same problem and it turned out to be a bad sensor. and buy oem if yours doesn't test as good.

        Comment

        • george graves
          I waste 90% of my day here and all I got was this stupid title
          • Oct 2003
          • 19983

          #5
          Swap relays. See if it's bad. And like greybeard said, I'd trust a used CPS over an ebay one.
          Originally posted by Matt-B
          hey does anyone know anyone who gets upset and makes electronics?

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          • tnicholls
            Noobie
            • Aug 2013
            • 21

            #6
            new cam sensor on the way hopefully thats it I've tested everything else.

            Comment

            • tnicholls
              Noobie
              • Aug 2013
              • 21

              #7
              So I tried new relay, new ecu, and new cam position sensor. Also confirmed the wire to the ecu for relay ground is good. Im not really sure what else it could be. When i jump the relay the pump runs strong.
              edit: Installing crank sensor tomorrow
              Last edited by tnicholls; 05-29-2018, 07:20 PM.

              Comment

              • tnicholls
                Noobie
                • Aug 2013
                • 21

                #8
                Installed crank sensor and it didn't make a difference. full pump still won't prime and car won't idle i need to hold the gas or the car will die

                Comment

                • george graves
                  I waste 90% of my day here and all I got was this stupid title
                  • Oct 2003
                  • 19983

                  #9
                  Silly question/....but you've double checked to make sure the lines aren't mixed up? I'm scratching my head here.
                  Originally posted by Matt-B
                  hey does anyone know anyone who gets upset and makes electronics?

                  Comment

                  • tnicholls
                    Noobie
                    • Aug 2013
                    • 21

                    #10
                    yes i checked the flow from the fuel pump when i jumped the relay. The pump still wont prime. I pulled the intake manifold to check for shorts in the wiring but i dont know what else to check, fingers crossed i find something grounding out.

                    Comment

                    • King Mufasa
                      E30 Addict
                      • Sep 2012
                      • 530

                      #11
                      Did you figure out the issue?

                      Comment

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