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Thread: Fuel Pump Desired Voltage Table - Dual GT Pumps - Returnless System

  1. #1
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    Fuel Pump Desired Voltage Table - Dual GT Pumps - Returnless System

    Can anybody point me in the direction of a write up on how to dial in the fuel pump voltage settings for a 2002 Mustang GT - Factory EEC-V - that has been upgraded to Dual Ford GT pumps / Dual FPDM in a returnless configuration ?

    Currently fuel pressure is very unstable and the fuel pump duty cycle is showing upwards of 114% at idle.

    Apparently this is something typically done in SCT. I cant seem to find anything HPT specific.




    Thanks in advance.

  2. #2
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    this the SCT settings return system

    Returnless Fuel Pump -> Fuel pump voltage table - set all the cells to max value, usually 15 volts.
    Returnless Fuel Pump -> scalar -> fuel pump gain integral term 0
    Returnless Fuel Pump -> scalar -> fuel pump gain derivative term 0
    Returnless Fuel Pump -> scalar -> fuel pump gain proportional term 0
    Returnless Fuel Pump -> Desired pressure drop across injectors - 4 PSI blow base pressure
    System Switches -> scalar -> fuel pump type 2
    Desired Pressure Drop Across Injectors should be ~10psi ABOVE the regulator pressure you are running.
    Fuelpump Tst Pressure Below to Allow test should be ~20psi BELOW the regulator pressure.
    Fuel Pump Type and Fuel Pump System Type should be 0 if present.
    Fixed Duty Cycle Mode Switch should be set to 0
    Fixed Duty Cycle to Run in Fixed mode should be 1.0.

    If Retaining the Rail Pressure Sensor Hardware, but using a Regulator to Control Fuel Pressure:
    Go into Returnless Fuel Pump / Fuel Pump Voltage Table:
    Set the entire table to 15?€™s.
    Go into Returnless Fuel Pump / Desired Pressure Drop Across Injectors:
    Set the Right Column to ~10psi above the Regulator Pressure you are running.
    Go into Returnless Fuel Pump / Scalar:
    Set Fuel Pump Gain Derivative Term, Fuel Pump Gain Integral Term, and Fuel Pump Gain Proportional Term all to 0.
    Set Fuelpump Tst Pressure Below to Allow Test to ~20psi below the Regulator Pressure you are running.
    Go into System Switches / Scalar:
    Set Fuel Pump Type and Fuel Pump System Type to 0 if present.
    If Eliminating all Returnless Components:
    Go into System Switches / Scalar:
    Set Fuel Pump Type and Fuel Pump System Type to 0 if present.
    Set All Fuel Injector Slope Multipliers & Breakpoint to 1.
    Last edited by mstang_man; 04-21-2019 at 12:59 PM. Reason: settings

  3. #3
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    That would be excellent. Thanks so much.

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  5. #5
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    This is great stuff.

    Just to confirm, the data added in Post 2 is only for Return systems correct ? As we are returnless, I would focus on post #4 Data ?

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    Returnless

    Quote Originally Posted by Weedwaka View Post
    This is great stuff.

    Just to confirm, the data added in Post 2 is only for Return systems correct ? As we are returnless, I would focus on post #4 Data ?
    Everything in the Word Docs and Excel are for Returnless Systems ..

  7. #7
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    That has been a great help.

    Do you happen to have the Gains (Derivative, Proportional, Integral) for dual Ford GT Pumps on a 2V Returnless system ? I was able to locate them on a 3V but I am not sure if its transferable.

  8. #8
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    If someone finds this I used the following settings to stabilize the fuel pressure thus far :


    Minimum On Time : 2.0 s
    Voltage Deadband : .0625
    P Gain : 0.0000
    I Gain : 0.1797
    D Gain : 0.0005

    I now have pretty steady commanded fuel pressure at start up and idle . It hardly moves much off the 40PSI at idle. I am sure these can be improved upon with tweeking.

    FIXED I do still have an indicated 88 - 114% fuel pump duty cycle at idle via Diablosport I2 scanner however and can not seem to locate the issue. The wiring to the FPDM all looks good and the duty cycle stays with either FPDM un plugged. Is there a reference for voltage the PCM uses to calculate duty cycle or is it done based on time on vs off like injectors ? / FIXED - Was Scanner


    Does anybody know what the Deadband setting and other fuel pump settings actually do ? I copied the above data points from another tuners file but I can not find any info on Deadband or the fuel pump Min / Max settings . The HPT descriptions are pretty vague here.
    Last edited by Weedwaka; 04-25-2019 at 09:53 AM. Reason: Correction and more Info

  9. #9
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    Hey guys,

    I am having trouble finding detailed explanations of these setting in the fuel pump tab. Can anybody shed some light on these ?


    Fuel Pump Gain Voltage Deadband: Fuel pump voltage will not be corrected if desired change is less than this. (Min / Max voltage adjustment trigger based on table vs pressure ? )

    Fuel Pump Low Limit Mult: Sets a lower limit for the fuel pump voltage, multiply by the base voltage lookup.

    Fuel Pump High Limit Mult: Sets an upper limit for the fuel pump voltage, multiply by the base voltage lookup.[/B]

    Fuel Pump Fixed Duty Cycle Mode: Master enable/disable for Fuel Pump fixed duty cycle mode.


    I see in some tunes the fixed duty cycle is disabled and in others this is enabled. When would this setting be advantageous to enable / disable ?

  10. #10
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    Ignore the duty cycle question. I have been chasing a problem that does not exist.

    The Diablosport i2 is reporting max pump duty cycle but our Aeroforce guage gives 36 - 38 FPDC at idle. Its an i2 pid issue of some kind.

  11. #11
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    This is a very good and important thread. Thanks (Mustang_Man) for uploading the EXCEL Sheet as it is very helpful but I couldn't find any data for the aftermarket upgraded fuel pump.

    So, if anyone have a good experiences on tuning Stryker Division X 340 LPH single Fuel Pump on new edge Mustang using SCT software?

    I think as they flow much more than Ford OEM pumps it will mess with "Fuel Pump Voltage Table" and will cause some spike drop in fuel pressure drop across injectors. So any rule of thump of how to deal with them in the tune.

    Appreciate the support.

  12. #12
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    Quote Originally Posted by Denver_roush View Post
    This is a very good and important thread. Thanks (Mustang_Man) for uploading the EXCEL Sheet as it is very helpful but I couldn't find any data for the aftermarket upgraded fuel pump.

    So, if anyone have a good experiences on tuning Stryker Division X 340 LPH single Fuel Pump on new edge Mustang using SCT software?

    I think as they flow much more than Ford OEM pumps it will mess with "Fuel Pump Voltage Table" and will cause some spike drop in fuel pressure drop across injectors. So any rule of thump of how to deal with them in the tune.

    Appreciate the support.
    you will have to data-log the Fuel pump voltage table and update the voltage based of the data-log. only takes a few minutes to fill the whole chart. I did it for Walbro 400lph pumps.