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Thread: Fuel rail pressure drops off at higher RPM

  1. #1
    Tuner in Training
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    Fuel rail pressure drops off at higher RPM

    Hey Guys,
    I have a 2014 Sierra with a 5.3 and 72mm turbo with about 8PSI, cast pistons, and crank.
    I am having trouble with the fuel rail pressure never really getting to the "Desired pressure", as the RPM rises it gets worse till it misfires and falls on it face.
    Any thoughts on how much I can turn up the settings on the Fuel pressure tab? or maybe I am missing something completely.
    Any help would be appreciated.

    Thanks19-07-30 curtis.hpl
    Last edited by CurtisErickson; 07-31-2019 at 11:06 PM.

  2. #2
    Senior Tuner Ben Charles's Avatar
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    Sounds like your out of fuel.. what’s injector MS, around 7 or higher?

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  3. #3
    Tuner in Training
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    It seems to be out of fuel at relatively low rpm though, I figured that would only happen nearing WOT
    I posted the log above

  4. #4
    Out of fuel. Time for injectors and a bigger pump. Increasing fuel pressure under fuel pressure tab will only cause more problems than it solves. It throws everything out of whack and you will have to retune it, and eventually you will need new injectors and pump anyway.

  5. #5
    Tuner in Training
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    I have read LT4 injectors and LT4 pump will help even if I use the same cam. Any advice on that?

  6. #6
    Senior Tuner eficalibrator's Avatar
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    The FIRST thing you need is an upgraded LOW SIDE pump. Then you can look at LT4 high side parts as well.