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Trying to diagnose fueling issue

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    Trying to diagnose fueling issue

    So I bought my car about a month ago and it runs great apart from during startup. It takes about 10-15 seconds of cranking on a cold start before it will fire off. I usually crank for 5 seconds, wait a few seconds and start cranking again. Occasionally I think the cold start injector is spraying because I'll get a sudden fire and then to back to cranking and eventually it will sputter for a bit and start up.

    For the first minute or two of driving the engine surges and feels inconsistent. But once it's warmed up it runs great. I verified last week that the tank pump is pumping fuel during cranking. I can't verify if the car has an external fuel pump or not. It's an '87 325 with an eta, I don't see a pump under the car. I see a fuel filter and what may be an anti-drainback valve.

    I don't want to just throw money at the problem and hope I fix it. I'd like to eliminate possibilities and make an educated decision. Does anyone have an idea what could be going on?
    Last edited by OldSkoolGP; 06-08-2016, 08:26 PM.

    #2
    I replaced the fuel filter and removed the damper. I also discovered that the connections for the primary fuel pump at some point were replaced with hardware store fork terminals. One wasn't even on tight as I was able to pull it off by hand. I soldered proper round lugs onto the wires, cleaned the terminals and put it all back together. I also tested the primary fuel pump off a battery and it does work. Still have the same problem. So it wasn't a clogged fuel filter.

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      #3
      Well, you guys are less than helpful. Guess I'll try some other forums.

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        #4
        clean the fuel injectors. I bet they are flowing less than half what they are supposed to. MEPEH is a great place and I have used his services 4 times now great everytime

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          #5
          check FPR to
          89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

          new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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            #6
            I am having the same problem on my 325es. Car runs normal once it fires though. I know the valve is good cause I put a new factory unit in a few months ago. Car also starts fine if I have been driving it. Feels like the fuel pressure bleeds off as it sits after a few hours. You guys think the fpr could cause this?

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              #7
              you guys are less than helpful
              OP already left.

              t
              now, sometimes I just mess with people. It's more entertaining that way. george graves

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                #8
                Well, I don't think the FPR is my problem. Car has been sitting a little over a week, I went to crank it up and it fired off immediately. If the FPR was dying it wouldn't have done that.

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                  #9
                  Injectors in good condition ?
                  89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                  new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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                    #10
                    Originally posted by digger View Post
                    Injectors in good condition ?
                    I presume. I have the old 1.0 Motronic system with the extra injection module for startup. Car runs great when running, plugs looked fine last time I pulled then, etc.

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