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    Fuel Pump Question

    I picked up a non running 1987 325is last week and today was the first chance I had to try and figure out what's wrong. The PO said they were driving one day and it just shut off without warning. They cranked it a few times and it restarted once for about 30 seconds and then shut off and wouldn't restart.

    I've had several cars that have done this exact same thing and it has always been the fuel pump.

    Today before going to the fuel pump I swapped in a CPS and main relay and fuel pump relay from a running car and none of that helped.

    I then jumped the fuel pump relay and the main pump under the car would run but not the one in the tank. This is an 03/87 car so it has two pumps. I then took a battery and set in on the floor in the back seat and ran one wire from each of the battery terminals and then touched the other end of each wire to the leads on the in tank fuel pump and nothing.

    So, the question is that if you directly energize the in tank fuel pump as I've described would that make it run if it was in working order, seems logical that it would. And I know, it's not the smartest thing to do since a spark could have happened while doing this right on top of the tank, but there was no leakage on top and no gas vapors so it worked out ok. Just don't want to spend the money on a new one if that's not the problem. The in tank pump looks to be the original fuel pump.

    Thanks

    #2
    And it's not the timing belt, I already checked that and it's not broken.

    Comment


      #3
      If you hooked straight power to it and it did not run it is bad.
      Current
      99 328i (Sold)
      91 318is M50B25TU
      89 325ix (Parted out)
      87 325is (Parted out)
      95 525i (Parted Motor for 91 318is)

      Comment


        #4
        ^^^ correct.

        Also make sure to respect the polarity (+) and (-). hooking it up backwards will run the pump backwards.

        If you can't hear anything when it is directly connected like you describe, it is likely dead.
        101

        The E30 collection:
        1987 325es M52 - Schwarz / Taurus Red Sport (son #2's)
        1987 325is - Delphin / Black Sport (son #3's)
        1987 325i Convertible - Triple Black
        1989 325iX Coupe - Diamondschwarz / Black Comfort
        1990 325iX Coupe - Sterling Silver / Grey Sport

        1981 Fiat 124 Spider 2000 - Green / Tan
        1998 Volvo V70 GLT - White / Tan
        1998 Volvo S70 T5 manual - White / Taupe
        2001 Ford Windstar - Silver / Grey (parts hauler)
        2006 Lexus GX470 - White / Tan (tow rig)

        Comment


          #5
          Run it backwards and it fills the tank with free gas!

          Comment


            #6
            Originally posted by Navarone View Post
            Run it backwards and it fills the tank with free gas!
            Man if that works I need to go get started. Does it make race gas when you do that?
            Current
            99 328i (Sold)
            91 318is M50B25TU
            89 325ix (Parted out)
            87 325is (Parted out)
            95 525i (Parted Motor for 91 318is)

            Comment


              #7
              Yeah, I tried the wires both ways, nothing either way. Ordering a new pump.

              Thanks for the info.

              Comment

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