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    Vapor-lock Causes?

    After doing lots of reading, researching, and asking I've come to the conclusion that my E30's issues are because of vapor-lock. In other words, I believe the fuel is boiling at some point before it gets to the injectors.

    First of all, anyone have this happen and cure it?

    The real issue is that if I take her on a long haul under heavy load, and especially in hotter weather she'll bog down, have really rough starts, or get to the point where she will stall and need to cool down (and have some throttle coaxing) to start back up. Rough bogging starts also happen if she sits in the hot sun for a long time.

    So far these are the things I can think of that may be causing/contributing:

    Low car (pavement in Tucson reaches 140+ °F on an average day)
    Hood's foam insulation is completely removed (it was shredded so I removed it)
    Cat/cover is loose (may be leaking exhaust)

    Does this seem plausible or am I over-thinking this problem?
    Different strokes for different folks.

    #2
    what kind of spark plugs are you running?

    Turbo M42 Build Thread :Here
    Ig:ryno_pzk
    I like the tuna here.
    Originally posted by lambo
    Buttchug. The official poster child of r3v.

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      #3
      The fuel system is a flow through design so it is very unlikely to suffer from vapor lock. More likely problems are a weak pump, a pump that is having to work too hard, flaky fuel pump relay, etc.
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

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        #4
        Running Bosch F7LDCR sparks, only a few months old.

        Pump is relatively new as well, because the old one was having problems (quite similar). I'm pretty sure something is making the fuel pump work too hard, and she runs rich sometimes (maybe all the time?).

        Is there any way to check a relay besides putting in a new/confirmed working one? Also, where is the fuel pump relay on a 318is? I looked around and no one had a clear answer besides possibly the furthest relay from the windshield in the box...

        Thanks guys.
        Different strokes for different folks.

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          #5
          Fuel relay would be the middle one out of 3 beside the fire wall. Realy is a switch type of unit, so it is either works or it does not. I remember another thread of yours ans I remeber you complained about hard starts when hot, so it is very unlikely the relay would be your problem.
          I'd think you have issue with fuel delivery. Rulling out the fuel pump, check your FPR and little vac hose attached to FPR, also you may have a jammed fuel hose...check these, some could be from when you changed fuel pump...

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            #6
            I've been debating changing every fuel line on the car... Do our cars have a fuel pressure gauge port anywhere or do you have to throw in a T adapter? (I'm assuming that is the only way to test FPR)

            People have mentioned checking fuel pump for rust, but when I took my old one out there was no sign of it and the filter was still clean.
            Different strokes for different folks.

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              #7
              similar problems have related to shitty spark plugs, maybe thats not the case here.

              The best way to monitor fuel pressure is to T in after the FPR and get fuel pressure at the rail.

              Turbo M42 Build Thread :Here
              Ig:ryno_pzk
              I like the tuna here.
              Originally posted by lambo
              Buttchug. The official poster child of r3v.

              Comment


                #8
                Thanks, I'll check it out. Do most auto stores rent out fuel pressure test stuff?
                Different strokes for different folks.

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