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Thread: 78 f150 4.6 swapped return fuel system need help!

  1. #1
    Tuner in Training
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    Jun 2018
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    ontario canada
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    78 f150 4.6 swapped return fuel system need help!

    I've been reaching the forum for weeks trying to figure out how to tune from returnless to return for this with no luck. Found lots for the gm stuff but nothing applied to me.

    Anyways I pulled the 4.6 2v and 4r70w out of a police interceptor. I used a ron Francis wiring harness that retained the stock fuel pump controller. All I have to do is tune it for the return system. The only options I get under the fuel system tab are:

    Flow max
    Desired voltage
    Off duty cycle

    I've changed all the values in the desired voltage to 12 volts. But when running it underdrives my pump to 2.4 and drops my fuel pressure to 23 psi

    Do I need to make changed under the engine tab?

    Right now the truck is undrivable. It idled great and sounds awesome but any acceleration it falls on its face and even pulls all timing.
    The only thing changed on the motor is fuel system. Otherwise it's still stock with long tubes and cold air

    If you need any more info please let me know!

  2. #2
    Tuner in Training
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    Jun 2018
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    ontario canada
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    Okay not getting much help on here but making progress on my own.

    So Ron Francis wiring sent me an sct tune which made the fuel pump actually run at the desired voltage. So I've set my fuel regulator to about 23 which gives the fuel rail 40psi. (What the stock desired pressure is)
    I had to unhook the vacuum line to the regulator as it just caused me problems so it's a constant 40 psi at all times.
    It runs way better and is actually drivable now however it's still not quite right.
    Is there anything in the tune I am overlooking? As far as I know I'm running a stock pressure so any injector multipliers or flow rates should stay at the stock value?

  3. #3
    Tuner in Training
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    What year crown vic?

  4. #4
    Tuner in Training
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    Came from a 2005 Vic

  5. #5
    Tuner in Training
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    Nov 2016
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    FPDM is not ment to be used with a return style fuel system. It can't control pressure so it pulls power.