low fuel pressure

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Superhauler, Sep 1, 2012.

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  1. Sep 1, 2012 #1
    Superhauler

    Superhauler TEACHER OF MEN

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    i'm stumped! my converted a-cert has low fuel pressure 70 to 80 lbs at idle and at high idle. changed trans pump and check valve and new suction lines from tanks. what am i'm missing. also shimed pump with no change.
     
    Superhauler, Sep 1, 2012
    Superhauler, Sep 1, 2012
    #1
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  3. Sep 1, 2012 #2
    Heavyd

    Heavyd Road Train Member

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    What is it supposed to have?
     
    Heavyd, Sep 1, 2012
    Heavyd, Sep 1, 2012
    #2
  4. Sep 1, 2012 #3
    Real Deal

    Real Deal Medium Load Member

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    Superhauler I have wondered that myself. I can't seem to make it the pressure change on my MRX pump.
     
    Real Deal, Sep 1, 2012
    Real Deal, Sep 1, 2012
    #3
  5. Sep 1, 2012 #4
    Real Deal

    Real Deal Medium Load Member

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    MRS pump. Seems like my guy at the Cat House told me about a check valve recently that will hold to 105.Going to check with him this week.
     
    Real Deal, Sep 1, 2012
    Real Deal, Sep 1, 2012
    #4
  7. Sep 1, 2012 #5
    Real Deal

    Real Deal Medium Load Member

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    Still trying to say mxs But this phone will not let it happen
     
    Real Deal, Sep 1, 2012
    Real Deal, Sep 1, 2012
    #5
  8. Sep 2, 2012 #6
    Gear head

    Gear head Medium Load Member

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    did you change the pressure regulator in secondary fuel filter housing.try pressure reg out of sdp serial engine they have a little higher fuel pressure. The fuel pressure is supposed to be 100 at 1400 rpm.
     
    Last edited: Sep 2, 2012
    Gear head, Sep 2, 2012
    Gear head, Sep 2, 2012
    #6
    EverLuc Thanks this.
  9. Sep 2, 2012 #7
    Superhauler

    Superhauler TEACHER OF MEN

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    yeah changed it no difference. it used to go to 95 lbs but now it wont change. even replaced trans pump with shim and put suction line in a bucket of fuel to eleminate a restriction in fuel lines from tanks.
     
    Superhauler, Sep 2, 2012
    Superhauler, Sep 2, 2012
    #7
  10. Sep 3, 2012 #8
    Gear head

    Gear head Medium Load Member

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    How does it run is it posible that one of the poppet valves in one the inj. Are weak.
     
    Gear head, Sep 3, 2012
    Gear head, Sep 3, 2012
    #8
  11. Sep 3, 2012 #9
    Mr. Haney

    Mr. Haney Road Train Member

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    The problem isn't an injector even if cylinder pressures entered the tip of the injector, the injection pressures would eventually rise above this and force the fuel out the tip. You have something obstructing fuel flow somewhere or a bad pump
     
    Mr. Haney, Sep 3, 2012
    Mr. Haney, Sep 3, 2012
    #9
  12. Sep 3, 2012 #10
    Gear head

    Gear head Medium Load Member

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    What about pick up tube opstruction.
     
    Gear head, Sep 3, 2012
    Gear head, Sep 3, 2012
    #10
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