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Need Help with Fuel/Air Problem

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    Need Help with Fuel/Air Problem

    My problem started after replacing the gas tank and both fuel pumps on my Euro 323i. The car ran mostly fine before the repair, except for the dirty gas and possible failing pumps.

    After the repair, the car would only start if the MAF was unplugged. I have a friend with another Euro E30 with the same MAF. We swapped them out - My car still had the same problem, and his ran fine, so I know the MAF is ok.

    Tonight I took the cover off my MAF, and found that if I hold the meter so the MAF is wide open, the car will run with it plugged in. It will however only run for a few minutes before just shutting down.

    I have triple checked for vacuum leaks, and found none. The fact that the car runs with the MAF wide open suggests vacuum leaks are not the problem.

    My thought now is that the fuel pressure regulator may be bad and the car is getting too much fuel. When the fuel pressure regulator fails, would it cause the fuel pressure to go up or down? Could the previous rusty tank have caused the regulator to fail by passing rusty gas through it?

    I'm also thinking there may be a timing problem. Does anyone know if that could cause this?

    My final thought is that the L-Jetronic computer is failing. I find this unlikely since those rarely fail because they're so simple, especially compared to the Motronic computers.

    Can anyone help me with any ideas? Any thoughts are greatly appreciated.

    Thank You

    #2
    I have triple checked for vacuum leaks, and found none. The fact that the car runs with the MAF wide open suggests vacuum leaks are not the problem.
    That really could suggest just the opposite. When you hold the MAF door wide open you are telling the DME that a lot of air is flowing into the engine and thus a lot of fuel is needed. That would compensate for intake leaks.
    My thought now is that the fuel pressure regulator may be bad and the car is getting too much fuel. When the fuel pressure regulator fails, would it cause the fuel pressure to go up or down? Could the previous rusty tank have caused the regulator to fail by passing rusty gas through it?
    A fuel pressure regulator can fail in such a way as to cause excessive rail pressure, or little rail pressure. Either is going to be a problem Tee in a pressure gauge to the line that feeds the fuel rail and see what the pressure is while cranking the engine.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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      #3
      I'm having a brain failure and don't have the books in front of me at the moment... on an 'is' which end of the rail is the 'in' side where the pressure gauge should go?

      TIA
      Ben
      Thelma-Louise, the '88is Chump Car - back to M20 power!

      2014 ChumpCar Season Schedule!
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        #4
        There are two fuel lines the supply hose goes directly to the rail and the return hose connect to the FPR.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

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