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New fuel pumps working no pressure

Discussion in 'Air Intake, Engine Electronics, Ignition & Exhaust' started by RLWard, Dec 7, 2017.

  1. RLWard

    RLWard New Member

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    Help! My 1987 F150 XLT Lariat (5.0 with dual tanks) will run on starter fluid only. I have pulled the bed and replaced: low pressure pumps in the tanks, high pressure pump on the frame rail, fuel filter, and fuel pressure regulator. It’s pushing fuel well out of the filter so that would appear to eliminate electrical issues. However, there’s no pressure at the rail...zero. The shraeder valve is wet just no pressure. Inertia switch is good, no diagnostic errors show on OBDI-1 tester.

    Could an injector or injectors be stuck open, and that’s why rail is wet but no pressure?

    What about the regulator? How can I check the vacuum to the regulator?

    I’m out of ideas and really discouraged.

    Any assistance is greatly appreciated! Thanks for reading.

    RLWard
  2. Dominick 1

    Dominick 1 Well-Known Member Respected Member

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    Very good info on this problem
    read it and the red high lighted posts
    http://www.fordforumsonline.com/posts/67894/
  3. Action

    Action Moderator Staff Member Respected Member

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    If you pull vacuum on FPR does it hold vacuum?

    Test the fuel pressure regulator diaphram with a suitable vacuum pump with an attached vacuum gauge. Pull a vacuum of about 20 inches at the vacuum port on the regulator and hold....the reading should not change.

    >>>>>>>>>>>>>>Action
  4. Action

    Action Moderator Staff Member Respected Member

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    There is another possibility with dual tanks. The tank selector valve on the frame rail is worn and you are pumping gas from one tank to the other.

    Have you seen fuel out if the filter?

    >>>>>>>>>>>>Action

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