motorcranks but wont start, has fuel and spark

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  • jlevie
    R3V OG
    • Nov 2006
    • 13530

    #16
    Assuming this is an M20 engine...

    The first check is to see if spark is present when cranking the engine. Spark at the coil lead, but not at all cylinders means bad ignition wires, bad distributor rotor/cap, or broken timing belt. A peek in the oil filler cap while cranking will tell if the cam is turning and thus if the belt is good. The next check is to see what the fuel rail pressure is while cranking. Too little or too much pressure will prevent the engine from firing.

    If there is spark and normal fuel pressure the next check is to use a noid light to find out if the injectors are all firing. If they are and this is a 325e you need to check the cold start valve and control sensors. Otherwise move on to checking for intake leaks. That means a smoke test of the intake.

    If it isn't obvious, you need the proper diagnostic tools (fuel pressure gauge, noid light, smoke machine) and may need spares (AFM, DME, Coil, etc) for diagnostic purposes. If you don't have all of that the best approach is to flat bed the car to a shop and have a pro figure it out.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

    Comment

    • tunethtmkII
      Wrencher
      • Apr 2011
      • 297

      #17
      obviously proper diagnostics are gonna need to be ran. this thread was for more looking for people that have had similiar experiences.
      Tuck tire. Poke rim.

      Comment

      • tunethtmkII
        Wrencher
        • Apr 2011
        • 297

        #18
        Did a fp test and got a 45psi while cranking. is that too high?
        Tuck tire. Poke rim.

        Comment

        • tunethtmkII
          Wrencher
          • Apr 2011
          • 297

          #19
          did some research. 45 psi seems to be normal.

          so i have proper fuel pressure and spark with a brand new cps....
          Tuck tire. Poke rim.

          Comment

          • jlevie
            R3V OG
            • Nov 2006
            • 13530

            #20
            So the next check should be for intake leaks, which means a smoke test...
            The car makes it possible, but the driver makes it happen.
            Jim Levie, Huntsville, AL

            Comment

            • Exodus_2pt0
              R3V Elite
              • Dec 2011
              • 5943

              #21
              Do a compression test first.
              No E30 Club
              Originally posted by MrBurgundy
              Anyways, mustangs are gay and mini vans are faster than your car, you just have to deal with that.

              Comment

              • tunethtmkII
                Wrencher
                • Apr 2011
                • 297

                #22
                Originally posted by Exodus_2pt0
                Do a compression test first.
                dont see how it would lose compression after sitting for three days. but i guess that will be the next check
                Tuck tire. Poke rim.

                Comment

                • Exodus_2pt0
                  R3V Elite
                  • Dec 2011
                  • 5943

                  #23
                  compression gauge is cheaper than renting a smoke machine. Spark, Fuel, Compression. Those are the basics of a running engine. If those 3 are good, then move on to other possibilities.
                  No E30 Club
                  Originally posted by MrBurgundy
                  Anyways, mustangs are gay and mini vans are faster than your car, you just have to deal with that.

                  Comment

                  • Savagefurai
                    E30 Modder
                    • Apr 2011
                    • 970

                    #24
                    hate to dig up an old thread but did OP figure this out?
                    Having the same issue
                    sigpic
                    Currently without an e30. Will probably die soon.

                    Comment

                    • tunethtmkII
                      Wrencher
                      • Apr 2011
                      • 297

                      #25
                      Originally posted by Savagefurai
                      hate to dig up an old thread but did OP figure this out?
                      Having the same issue
                      Full tuneup fixed her
                      Tuck tire. Poke rim.

                      Comment

                      • Snou52
                        Advanced Member
                        • Nov 2011
                        • 176

                        #26
                        what do you mean by full tune up?

                        plugs, wires, distributor cap, and rotor?
                        1988 325is 237k

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