2003 F250 - Suddenly running "rough" under load?!!

Discussion in 'Engine & Performance' started by maanonsen, Nov 3, 2018.

  1. maanonsen

    maanonsen Junior Member

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    I have a 2003 F250, 5.4lt (?) motor. It was running fine. I went to pickup a Washer and noticed the gas gauge was not moving, sure enough I coasted into a gas station and got $20.00 worth.

    After that (+ 2 months ago), it immediately started sputtering under load. It idles just fine, however, when you are driving, it will start sputtering and I have to mess with the gas pedal to keep going, weirdest thing!

    So, it's been long enough to know it is not water in the gas, I have replaced the fuel filter, which did help a little. I would liken it to a spark plug "missing" except I have fuel injection. I check all the coil connections, put fuel conditioner in it and it is still missing? However, like I said, it will idle all day just fine.

    Anyone have any ideas what I can check or do next? I have zero trouble codes, replaced the filter, and now I am running out of ideas on what to try next? It is weird how it suddenly started doing this! Someone said I may want to check the fuel pressure regulator? I don't know what of where that is even?

    Any advice is greatly appreciated!
     
  2. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    Sounds like fuel pressure is weak @maanonsen

    Does your Autozone have a loan a tool program
    to lend you a fuel pressure testing gauge ?

    Most often the Check Engine Light will come on
    if the fuel injection pressure regulator is defective.
     
  3. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    https://www.rockauto.com/en/catalog...+&+air,fuel+injection+pressure+regulator,6124

    This the link to the fuel injection pressure regulator
    part and price but you need to figure out if it is the
    regulator that is defective or the fuel pump.

    Here is how to remove the regulator on a 4.6, similar on a 5.4


    If the fuel pump is bad, you will have to remove the
    bed or drop the tank to replace it, the fuel pump is in
    the tank.
     
  4. maanonsen

    maanonsen Junior Member

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    Hey Rousch PSD,

    My Local Autozone DID have a rental kit, looks lke a vacuum gauge and a multimeter. I am going to read the directions now, and give it a "whirl." Thanks for the tips and info!

    I'll let you know how I make out, thanks again.

    maanonsen

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  5. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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  6. maanonsen

    maanonsen Junior Member

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    Roush OSD,

    So, I used the test kit and I "think" I'm ok with the Fuel Pressure regulator. It said it should read between 3-10psi with just the key on, but I had a hard time trying to get a reading like that. When I started the motor it steadily climbed, between 15-20 lbs., and then I turned it off as I was not sure it would stop at all and blow out the meter, lol.

    My point is I think I have plently of pressure, and as you stated my check engine light should have gone on if this part was bad, but my mine never came on.

    Any idea(s) what I could check next? I replaced the fuel filter, and now it looks like the fuel pressure regulator is good, not sure what I can check next?

    Thanks!
    maanonsen
    *************************************************************
     
  7. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    Here is a chart for 2003:

    Fuel pressure 2003.png @maanonsen

    Specs on your truck: 2003 F250 with 5.4 are minimum of
    30psi for fuel pressure.
    Should jump to 45psi when you remove the vacuum hose
    from the fuel pressure regulator.

    In My Opinion you have low fuel pressure that is pump related.
     

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