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Thread: "F" 250 as the ultimate tow rig! Can it be?

  1. #31
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    My stock fuel pump had a check valve and held pressure, even when the pump was only pushing 12psi. The new pump didn't and immediately went to 0 when the car was shut off.

    I think the newer pumps just don't use them.
    Quote Originally Posted by jcassity
    I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
    Hooligans!
    1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
    1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
    1986 cougar.
    lilsammywasapunkrocker@yahoo.com

  2. #32
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    I think I found the problem. The regulator is not working well. Under load the fuel pressure drops off. Not sure if it's the regulator seat or plunger. Appears the diaphragm is still fine but something else is not working correctly. I have a stock fuel rail and regulator and I'm gonna try that with the 24# injectors.

  3. #33
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    Hope that is part of the problem but dips in pressure also indicate lack of enough volume.

  4. #34
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    Quote Originally Posted by Aerocoupe View Post
    Hope that is part of the problem but dips in pressure also indicate lack of enough volume.
    I agree, but feel some of the volume is being limited possibly by the regulator returning needed fuel. I will cross that bridge once I determine if replacing the regulator makes a difference. There may not be an issue after that. After all, these pumps also fed 460 powered trucks, they should be enough for a 351 with heads and a lightning intake.

  5. #35
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    The key to this one as Aerocoupe said, the fuel pressure is fluctuating all over the gauge as well as the rail did not hold pressure after the key was off. These trucks have issues with the 1 way check valve on the fuel supply side that normally causes issues. This was not the case for me as it was not filling from tank to tank, which is the usual characteristic.

    So I did find the issue. The regulator was hanging open. I pulled the rails and 19# injectors out and blew through the inlet and air was coming out the return. That should not happen until the adjusted pressure is reached. Since I did this by mouth, I doubt I reached 40ish lbs.

    I replaced the rails with a stock 1994 set with a factory regulator as well as I crawled underneath to look at the fuel filter. It had a cheap Chinese duralast filter, so pitched it in the trash and installed a Motorcraft. Bang! Easy 30 hp and 100 foot lbs of tq. Now it's impressive! I'm excited to tow with it again!

  6. #36
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    Finally got a code! 38, Idle tracking switch.... Assuming the IAC is taking a dump. Gonna try to clean it and see what happens.

  7. #37
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    OK, so I've had enough of this Speed Density system. Its impossible to tune out the issues since I changed the heads and cam. It's gonna get real for the truck cause I'm going 1993 Cobra X3Z computer and Mass Air. I am sick of the erroneous computer codes and Full rich check engine lights. There is nothing left to replace or eliminate.

    I'll post pictures and a write up as to why some things are the way they are! I am not using a 302 HO or 351 camshaft, so gonna have to move some injectors in the harness and consolidate the placement of the O2's.

  8. #38
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    BTW, using a Painless harness I had left from another project, so I'm gonna have to make it work.

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