m20b25 start then dies. has fuel spark but no air?

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  • Fcknslo
    Advanced Member
    • Nov 2009
    • 171

    #1

    m20b25 start then dies. has fuel spark but no air?

    as title states. I know for a fact that the fuel pump works. replaced and checked fused even hotwired and all works fine. has consistant fuel pressure till it dies. check injectors with noid light and they pulse till the car dies as well. spark has been tested and it seems to start just fine and run anywhere from 2 to 10 seconds then die out. possible bad air leak? what is your suggestion?
  • Fcknslo
    Advanced Member
    • Nov 2009
    • 171

    #2
    I have done my research and still come up empty handed. any suggestions?

    Comment

    • jlevie
      R3V OG
      • Nov 2006
      • 13530

      #3
      This sounds most like an intake leak or a fuel problem.

      What is the fuel rail pressure and what car is it? If you can't locate any intake leaks you may have to take the car to a shop that can run a smoke test.
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

      Comment

      • Fcknslo
        Advanced Member
        • Nov 2009
        • 171

        #4
        its a 91 with m20b25 swap. and fuel is consistant. the injectors pulse and am getting spark till the car dies out. I would do the spray carb cleaner and see if it idles funny but cant get the car to run for more than 10 seconds. smoke test seems to be the idea to follow

        Comment

        • jlevie
          R3V OG
          • Nov 2006
          • 13530

          #5
          Maybe I'm misinterpreting what you mean "fuel is consistant", but if you aren't measuring fuel pressure in the rail you can't say that a fuel problem doesn't exist.
          The car makes it possible, but the driver makes it happen.
          Jim Levie, Huntsville, AL

          Comment

          • Fcknslo
            Advanced Member
            • Nov 2009
            • 171

            #6
            fuel pressure is measured at fuel line before cold start and stays at 40 something psi consistantly till it dies

            Comment

            • Fcknslo
              Advanced Member
              • Nov 2009
              • 171

              #7
              bumpp

              Comment

              • Fcknslo
                Advanced Member
                • Nov 2009
                • 171

                #8
                bump. need help.

                Comment

                • Fcknslo
                  Advanced Member
                  • Nov 2009
                  • 171

                  #9
                  and on a side note, even when feathering the gas It doesn't make a difference so even with the gas pedal all the way down can the intake leak be that bad?

                  Comment

                  • Fcknslo
                    Advanced Member
                    • Nov 2009
                    • 171

                    #10
                    bumppppppppppppppppppppppp

                    Comment

                    • SmokeE30
                      E30 Mastermind
                      • Jun 2009
                      • 1730

                      #11
                      test for vacuum leaks, you should be making around 19in of vacuum at idle if it is less then that then start looking for them, ether usualy helps with that.
                      Shawn @ Bimmerbuddies
                      Bimmerbuddies LLC
                      717-388-1256
                      2971a Roundtop Rd, Middletown PA 17057
                      bimmerbuddiesllc@gmail.com

                      Comment

                      • E30QC
                        Wrencher
                        • Mar 2009
                        • 214

                        #12
                        are you saying the spark dies and the fuel aftert the engine starts choking?>

                        Comment

                        • metalix1021
                          Wrencher
                          • Apr 2008
                          • 246

                          #13
                          You're not giving enough information. You want help but aren't spending time to answer the questions that the guys ask in detail.

                          jlevie asked what the fuel pressure at the rail is, 40 something psi.....do you mean 49psi? 40.1psi? it can make a difference. The difference tells of a bad FPR or not.

                          You start it, when it does run for those 10 seconds, does it misfire like crazy? Idle lope?

                          Do you smell gas? does it backfire?

                          Comment

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