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325es Fuel Issues - Need help diagnosing!

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    325es Fuel Issues - Need help diagnosing!

    I just picked up an 86 325es and I'm trying to diagnose some serious fuel issues before I swap the top end out for an "i" setup.

    So here's what I know so far:

    1. I replaced the FPR
    a. The car does run smoother, I did not have any "violent" rocking of the car on my drive home
    b. the car is still dumping fuel, the whole way home I could see the black smoke out the back
    c. there is less "large pulsations" during idle

    2. If I stop the car and let the car sit for 5-10 seconds with the engine off, I can then turn the car on and accelerate normally through the first 4 gears all the way to redline (didn't try 5th)
    a. During acceleration, there is no interruption in fuel supply, no rocking or apparent hesitation
    b. The engine appears to operate correctly

    3. If I maintain speed for a few minutes, not at wide open throttle, and then attempt the accelerate, nothing happens
    a. the engine feels as if it is either 1) flooded or 2) simply not operating
    b. when the engine "stops" the engine & exhaust noise goes away completely (as if nothing is happening)

    4. I've had the internal fuel pump disconnected the entire time (it was the only way to make it home from delaware)

    5. The external fuel pump whines VERY loud

    6. There do not appear to be any fuel leaks anywhere on the car.


    Here's what we've deduced from some of the receipts in the car:

    1. The cylinder head was rebuilt with new seals around 99k miles (the car currently has 133k)

    2. In 2008, the owner purchased new Internal and External fuel pumps from a local auto parts store. I can't confirm they are oem parts but they do look correct.


    Any help is greatly appreciated, my last few e30's were 325i's and I've never had a fuel issue like this before. These damn eta engines are too convoluted and I having a lot fo trouble diagnosing the problem. I'm going to replace the fuel pumps regardless.
    stephenbrody.com

    #2
    With the internal pump disconnected I'd be surprised if the engine runs at all when the tank drops below 3/4. That would make the high pressure pump have to work a lot harder and it would make noise. Other possibilities are a tank with a lot of rust sediment in it or an obstruction the fuel supply or return lines.

    Tee a gauge into the fuel line the cores to the fuel rail, zip tie the gauge to a wind shield wiper, and see what the pressure does while driving.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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