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    #1

    fuel pressure?

    i put a new motorcraft fuel filter on and a motorcraft fuel pressure regulator got around 30 psi at test port
    shut car off pressure stays steady no sudden leak down.but when i drive the car to get it to 195-200* the fuel pressure goes to 40 psi
    i checked the fuel pressure regulator by pulling vacuum line and no gas coming out kept vacuum off for a while to see if gas would come out and nothing put vacuum line back on and shut car off.try to start up when hot and it just cranks what could cause this
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    #2
    vacuum off (or WOT) should be about 40... vacuum on at idle should be about 30. The no start could be a few things. Bad temp sensor when hot (reads open or short). Bad TPS making the computer think throttle is wide open. ECA/fuel pump relay being flaky.

    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
    rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

    Originally posted by gadget73
    ... and it should all work like magic and unicorns and stuff.

    Originally posted by dmccaig
    Overhead, some poor bastards are flying in airplanes.

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      #3
      question is why when hot fuel pressure goes to 40 psi with vacuum on is this normal.i replaced ect,act sensors. ill check tps and ECA/fuel pump relay

      Comment

        #4
        Check the vacuum line to the FPR. If it's collapsing when hot, that could be the cause. Or if it has some schmoo in it. May also be an issue with the FPR. Do you have a hand vacuum pump? If so... try pulling a vacuum on the FPR and then starting it when hot.

        Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
        rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

        Originally posted by gadget73
        ... and it should all work like magic and unicorns and stuff.

        Originally posted by dmccaig
        Overhead, some poor bastards are flying in airplanes.

        Comment

          #5
          Probably unrelated but worth mentioning is Ashley's old '89 TC would crank & crank to beat the band sometimes before it started, was typically worse when hot. I never had the intelligence to figure out why as when it fired up, it ran beautifully. LTDman83 bought it and that irritated him to the point of fixing it. It turned out to be the fuel pressure regulator. I had swapped distributors and TFI modules thinking that was what ailed it.
          1985 LTD Crown Victoria - SOLD
          1988 Town Car Signature - Current Party Barge

          Comment

            #6
            The Mad Marquis starts instantly when cold. But after a 20 minute heat soak after running around... it would take up to 5 seconds to turn over.
            +1 never figured out why. Once it fired... it ran like a champ. But that was usually only in the dead of summer.

            Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. -- Albert Einstein
            rides: 93 Crown Vic LX (The Red Velvet Cake), 2000 Crown Vic base model (Sandy), 2003 Expedition (the vacation beast)

            Originally posted by gadget73
            ... and it should all work like magic and unicorns and stuff.

            Originally posted by dmccaig
            Overhead, some poor bastards are flying in airplanes.

            Comment

              #7
              put smoke machine on car and found leak under manifold where the vacuum tree is and the line to fpr.took off put new teflon on threds and new line to fpr
              and she starts hot.i know now to check before i buy parts

              Comment

                #8
                Good deal. I'm slowly learning that myself. Diagnose, not replace.
                1985 LTD Crown Victoria - SOLD
                1988 Town Car Signature - Current Party Barge

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