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  1. #1

    Default CFI

    Did a leak down test on the CFI unit. It doesn't hold at all. Less than a minute the PSI drops.

    Injector spray is ok. Nothing bad.

    But, I'm thinking the CFI unit needs a rebuild. New injector o-rings and all.

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    This is for the 85 LTD LX
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
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  2. #2
    FEP Member slpr50ltd's Avatar
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    Will be interested to see if that resolves your issue! Good luck!!
    Last edited by slpr50ltd; 04-24-2012 at 04:01 PM.
    Brien "Pobs"

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  3. #3
    FEP Senior Member 4EYED85's Avatar
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    What kind of issue are we trying to solve?

  4. #4

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    Well, the fact that the System doesn't hold pressure for even a minute when the car is off is one issue.

    Still has an off idle hesitation. Not been able to get rid of that no matter what.

    Constant Code 41R in KOER. New O2.
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  5. #5

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    Unless the fuel is actually leaking down the throttle body, you're describing a symptom
    of a failing fuel pressure regulator.

    KOER 41 on CFI is a lean condition.
    Last edited by JACook; 04-24-2012 at 05:01 PM.
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    Jeff Cook

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  6. #6

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    Quote Originally Posted by JACook View Post
    Unless the fuel is actually leaking down the throttle body, you're describing a symptom
    of a failing fuel pressure regulator.

    KOER 41 on CFI is a lean condition.
    Thanks Jeff. I'll swap out the FPR!
    1985 Mustang GT Mild 331 4bbl 5 spd, 1985 SEFI LTD LX AOD.
    Cardomain: http://www.cardomain.com/ride/565542
    Mid Size LTD LX Facebook page! http://www.facebook.com/groups/233213650060739/

  7. #7
    FEP Member LSCR351's Avatar
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    I would bet on it NOT being the FPR, but a leak in a line or fitting. How about the little rubber hose in the tank, number one failure.
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  8. #8

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    I had a similar issue with mine a while back, I took off the hood and proped the pressure gauge where I could see it while driving to see if I was getting good pressure under load. It wasnt, but I was at 38 psi. I think these things want 40-42 to run well. I put a socket over the fpr and gave it a few light taps to literally push it in, effectively lowering the diaphram and upping the pressure. I did it with the car running as to not go to far. a few light taps bumped it up to 40. Took it for a drive and it ran great with absolutely no hesitation. it doesnt seem to be running rich, and isnt throwing a rich o2 code. I believe I was getting a lean code prior. I have put a few thousand miles on it since and it is still running great. I have a hunch the stock FPR is set to be JUST good enough to run it, but run it pretty lean, as to get better mileage.

    ford didnt like to feed these cfi cars much fuel for some reason. In my old 85 tempo with cfi ANY mod would max the fuel system. Just a custom made long tube header, cat delete, a high flow muffler and a custom made cold air system was enough to make it run lean enough to get some hesitation. The injector was maxed out on that car. I upped the pressure (that car had an adjusting screw) and it did nothing. I ended up having to swap in a higher flow injector along with tweaking pressure. Never had an issue after. I also tried a cfi TB rebuild kit on said car and that did no good either.
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