fuel gauge PLEASE HELP!!!

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  • e30power7931
    Noobie
    • Jan 2009
    • 20

    #1

    fuel gauge PLEASE HELP!!!

    Sorry if this is in the wrong section..im new.....my 87 325is has a strange gas gauge. bare with me im gonna explain lol. When i reach half a tank im empty and the light comes on.....i have replaced the fuel sender numerous times and checked the ground and tried other working gauges but nothing helps....when i hit empty i can only add 12 gallons tops.....im so confused. PLEASE HELP ME!! lol...Has anyone ever even seen this happen before? even my master technition who has worked on e30s and e28s forever is stumped....once again Thanks!
  • accident
    R3V OG
    • Sep 2008
    • 7303

    #2
    Originally posted by e30power7931
    Sorry if this is in the wrong section..im new.....my 87 325is has a strange gas gauge. bare with me im gonna explain lol. When i reach half a tank im empty and the light comes on.....i have replaced the fuel sender numerous times and checked the ground and tried other working gauges but nothing helps....when i hit empty i can only add 12 gallons tops.....im so confused. PLEASE HELP ME!! lol...Has anyone ever even seen this happen before? even my master technition who has worked on e30s and e28s forever is stumped....once again Thanks!
    How big do you think your gas tank is? IIRC the e30 tank is between 14.5-16.5, and if you're hitting gas light and putting in 12 gallons it sounds like you're pretty on par.

    Originally posted by ROLLingKING
    i have a bronzit and plan on making it look sweet.
    Originally posted by slammin.e28
    Moral of this story?

    If you drive your e30 on stairs, you're gonna have a bad time.

    Comment

    • e30power7931
      Noobie
      • Jan 2009
      • 20

      #3
      i think its a 15 but i have no idea im still pretty new to bmws lol....but im mostly concerned with the fuel gauge.....and my obc will say when im empty that i have like 30 liters left....WTF!!!! lol

      Comment

      • accident
        R3V OG
        • Sep 2008
        • 7303

        #4
        The OBC isnt very acurate. Please explain your fuel gauge issues better.

        Originally posted by ROLLingKING
        i have a bronzit and plan on making it look sweet.
        Originally posted by slammin.e28
        Moral of this story?

        If you drive your e30 on stairs, you're gonna have a bad time.

        Comment

        • e30power7931
          Noobie
          • Jan 2009
          • 20

          #5
          when i fill up the gauge goes to full. when the low fuel light comes on i am at half a tank and the range meter usually says about 155 miles to go but falls every few feet and also when i fill up it will say about 450+ miles which i know is very unaccurate

          Comment

          • accident
            R3V OG
            • Sep 2008
            • 7303

            #6
            how do you know you're at 1/2 tank?

            Originally posted by ROLLingKING
            i have a bronzit and plan on making it look sweet.
            Originally posted by slammin.e28
            Moral of this story?

            If you drive your e30 on stairs, you're gonna have a bad time.

            Comment

            • e30power7931
              Noobie
              • Jan 2009
              • 20

              #7
              that is what my gauge is displaying

              Comment

              • accident
                R3V OG
                • Sep 2008
                • 7303

                #8
                Originally posted by e30power7931
                that is what my gauge is displaying
                So when the gauge gets to 1/2 the gas light comes on?

                Originally posted by ROLLingKING
                i have a bronzit and plan on making it look sweet.
                Originally posted by slammin.e28
                Moral of this story?

                If you drive your e30 on stairs, you're gonna have a bad time.

                Comment

                • e30power7931
                  Noobie
                  • Jan 2009
                  • 20

                  #9
                  yeah

                  Comment

                  • accident
                    R3V OG
                    • Sep 2008
                    • 7303

                    #10
                    have you tried replacing the whole cluster? the SI Board or the rest of the electronics could be bad.

                    Originally posted by ROLLingKING
                    i have a bronzit and plan on making it look sweet.
                    Originally posted by slammin.e28
                    Moral of this story?

                    If you drive your e30 on stairs, you're gonna have a bad time.

                    Comment

                    • Jean
                      Moderator
                      • Aug 2006
                      • 18228

                      #11
                      Do you have correct cluster or sender in your car? this happens if you have a late cluster in an early car. Fuel gauge will not read correctly.

                      The "Empty fuel" light indicator is triggered when the float in the sender is clost to the bottom, so it's almost an ON/OFF switch where the sender/gauge are dependent on each other to give you correct reading.
                      Mtech1 v8 build thread - https://www.r3vlimited.com/board/sho...d.php?t=413205



                      OEM v8 manual chip or dme - https://www.r3vlimited.com/board/sho....php?p=4938827

                      Comment

                      • accident
                        R3V OG
                        • Sep 2008
                        • 7303

                        #12
                        Jean, would the gas light turn on at 1/2 tank with a late cluster in an early car? From what he's saying it seems like the needle itself is working fine, but the light is wonky.

                        Originally posted by ROLLingKING
                        i have a bronzit and plan on making it look sweet.
                        Originally posted by slammin.e28
                        Moral of this story?

                        If you drive your e30 on stairs, you're gonna have a bad time.

                        Comment

                        • e30power7931
                          Noobie
                          • Jan 2009
                          • 20

                          #13
                          i have replaced the cluster 3 times 2 times with 87 model clusters and my current one is from an early 88 cuz the tach went bad....in all of them the gauge never worked and i put in the correct sender all 5 times i have tried.....im thinkin about givin up and sayin ive done all i can all we can do now is hope lol

                          Comment

                          • accident
                            R3V OG
                            • Sep 2008
                            • 7303

                            #14
                            Ecu?

                            Originally posted by ROLLingKING
                            i have a bronzit and plan on making it look sweet.
                            Originally posted by slammin.e28
                            Moral of this story?

                            If you drive your e30 on stairs, you're gonna have a bad time.

                            Comment

                            • Jean
                              Moderator
                              • Aug 2006
                              • 18228

                              #15
                              According to realoem your car has one fuel level sender, correct? http://www.realoem.com/bmw/showparts...46&hg=16&fg=05

                              You can do the following test:

                              a) disconnect the wiring from the sender unit, one of the 3 wires activates the dummy light, and another is for the gauge, 3rd is ground. when you short one, the light comes on. test it.

                              b) remove the sender and place it in a bottle of water or any other liquid while moving it up and down to simulate the amount of gas in the tank. measure the resistance with a DMM

                              c) replace the sender with a variable resistor and see how the gauge behaves, does it sweep the full empty-to-full rotation? you'll need to look up what resistance your gauge needs.

                              I've done this on my early car, IIRC the range was 4ohms to 70-80ohms for the sender.
                              Mtech1 v8 build thread - https://www.r3vlimited.com/board/sho...d.php?t=413205



                              OEM v8 manual chip or dme - https://www.r3vlimited.com/board/sho....php?p=4938827

                              Comment

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