What killed my motor? I think it's fuel-related

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  • DrewC
    Member
    • Nov 2008
    • 61

    #1

    What killed my motor? I think it's fuel-related

    Just acquired an '86 ES and it started like a top. Been gutting it out the last couple days for LeMons prep and now it won't start. I can't hear a fuel pump when I turn the key on.

    Are there any safety/security features that could be killing the fuel relay since I've removed the dash, gauge cluster, wheel, etc? I didn't cut any important wires, or so I thought. I want to get this running before I head back to school Sunday.

    Any help appreciated! Thanks!

    1986 325ES LeMons Racer
  • Lurker27
    E30 Modder
    • Jul 2007
    • 821

    #2
    bypass the fuel relay to check if that's getting power to the relay, and if the relay is tripping to give power. You'll need a multimeter for this. Bentley's guide is very good.

    I don't think any safety features kills the fuel pump but I am not sure (nor am I really informed enough to comment)

    I had corrosion in the power line from the relay to the pump and had to run a new wire.
    '89 335is +turbo

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    • DrewC
      Member
      • Nov 2008
      • 61

      #3
      I decided to pull the plugs and take a look. Plugs are wet, no spark. Tried 2 different plugs, neither one lit up.

      What's the best way to hunt that out?

      1986 325ES LeMons Racer

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      • Lurker27
        E30 Modder
        • Jul 2007
        • 821

        #4
        Do you have a Bentley manual? They're worth their weight in gold.

        It's good that you've eliminated air and fuel, and its on to spark. First thing I'd do is check all the connections thoroughly. Beyond that I don't know the algorithms for testing that system off the top of my head, sorry.

        Good luck!
        '89 335is +turbo

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        • Kingb
          E30 Modder
          • Aug 2008
          • 928

          #5
          Crank position sensor. That is exactly what mine did. Like they said use the bently and a multimeter
          Originally posted by Nicademus
          My car beats off to that car. :bow:

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          • DrewC
            Member
            • Nov 2008
            • 61

            #6
            Originally posted by Kingb
            Crank position sensor. That is exactly what mine did. Like they said use the bently and a multimeter
            I don't have either. I'm home for Thanksgiving and trying to get it fired back up before heading out of town since I don't get back till the 18th (shake-down track day on Jan 4th).

            I guess I'll just look up some pics/schematics on the CPS and try and track it down...do you think it died or could be loose/unplugged?

            1986 325ES LeMons Racer

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            • DCColegrove
              Banned
              • Dec 2007
              • 2748

              #7
              Take a look at your Cap and Rotor...

              Comment

              • DrewC
                Member
                • Nov 2008
                • 61

                #8
                Originally posted by DCColegrove
                Take a look at your Cap and Rotor...
                The car fired 2 days ago, I doubt something went bad just sitting.

                1986 325ES LeMons Racer

                Comment

                • DCColegrove
                  Banned
                  • Dec 2007
                  • 2748

                  #9
                  Originally posted by DrewC
                  The car fired 2 days ago, I doubt something went bad just sitting.
                  Wet plugs no spark...

                  Just a direction to look... I've seen it more than once or twice.

                  Comment

                  • DrewC
                    Member
                    • Nov 2008
                    • 61

                    #10
                    Originally posted by Kingb
                    Crank position sensor. That is exactly what mine did. Like they said use the bently and a multimeter
                    I'm going to investigate this more but I was under the impression this didn't effect spark itself. i.e...it messes with timing of the spark and therefore the car won't start but if the CPS is screwy the spark plugs should still light up.

                    Is this theory flawed?

                    1986 325ES LeMons Racer

                    Comment

                    • SpecM
                      R3V Elite
                      • Oct 2005
                      • 4531

                      #11
                      Originally posted by DrewC
                      I'm going to investigate this more but I was under the impression this didn't effect spark itself. i.e...it messes with timing of the spark and therefore the car won't start but if the CPS is screwy the spark plugs should still light up.

                      Is this theory flawed?
                      yes, that is flawed

                      if the CPS is screwy enough, it will not produce a signal. No signal = no spark

                      You asked for help, that's fine. But then you shot down two ideas, good ideas, mind you, that you said it can't be (cap/rotor, and CPS), for no reason other than that's not what you "think" it is. Listin to us (exp Colegrove, he knows things), and check the entire ignition system.
                      1989 cirrisblau-metallic 325i

                      Comment

                      • DrewC
                        Member
                        • Nov 2008
                        • 61

                        #12
                        Originally posted by SpecM
                        yes, that is flawed

                        if the CPS is screwy enough, it will not produce a signal. No signal = no spark

                        You asked for help, that's fine. But then you shot down two ideas, good ideas, mind you, that you said it can't be (cap/rotor, and CPS), for no reason other than that's not what you "think" it is. Listin to us (exp Colegrove, he knows things), and check the entire ignition system.
                        Didn't discount the CPS. Cap and rotor checked out fine. Here's a bunch of pics I took, someone asked me on another board if I "disconnected 2 green connectors from a large black relay box down by the steering column". Could this be the culprit? (I think what he might be talking about is in the first pic). What would that have done/what's it control?

                        Thanks for the help guys. I'll post the rest of my pics below in case you spot anything funky.




                        1986 325ES LeMons Racer

                        Comment

                        • Rocco335i
                          Advanced Member
                          • Sep 2008
                          • 104

                          #13
                          its the cps mine did the same thing i rewired the cps and it worked fine for a week or so then just shit the bed put in one from my parts car works just fine
                          ITS THE CPS TRUST US

                          Comment

                          • DrewC
                            Member
                            • Nov 2008
                            • 61

                            #14
                            Originally posted by Rocco335i
                            its the cps mine did the same thing i rewired the cps and it worked fine for a week or so then just shit the bed put in one from my parts car works just fine
                            ITS THE CPS TRUST US
                            It actually turned out to be this little plug with the green wires running into it. It got disconnected while I was gutting the dash and all. I took some pics of all the wiring and someone on another board spotted this out. It runs!!!!! Big relief....


                            1986 325ES LeMons Racer

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