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Thread: 73 MFI Problems

  1. #1

    Question 73 MFI Problems

    Car: '73 911S - stock

    Getting my restoration project back on the road finally!!!

    Engine starts ok when cold, and once warmed up, runs
    very nicely without any mid-range surge. Idle is good,
    and CO is at 3.5% at idle and 3-4% at 2500-3500 rpm,
    so the rack seams to be adjusted correctly. Ignition
    timing is also on correct.

    When the car is warmed up, the engine will start if
    you try immidiatly, but if you let it sit for more than
    a minute, it will not re-start. The cold-start
    injectors are not squirting (as they shouldn't) at
    this point. I don't really know if I'm getting
    too much or too little fuel at this point.
    The car will re-start fine in about 2-3 hours.

    I removed the injectors to soak them in Ventil Sauber
    overnight, and when disconnecting the fuel lines from
    the injectors, it seamed like the lines were dry (at
    this point the car had sat for 4 hours). Is there some
    sort of check valve in the MFI pump to keep the lines
    filled, or is the pump expected to re-fill the lines
    once you crank?

    I'm not quite sure where to go from here, so if any one
    had a similar problem, any thoughts or advice??



  2. #2
    There should be pressure in the lines as the injectors usually don't open untill about 220psi....... I usually pressure check the injectors before I reinstall them and check for proper spray pattern...... perhaps your pump is on the way out and leaking internally.....

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