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
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  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.
     
  8. Bdons-SD

    Bdons-SD Anti spark plug!

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    My 05 expedition just started doing this with the 3v 5.4. Idled all day just fine, the second I gave it some gas it shuttered and misfired. No code. It was the number 8 coil going out. I’ve owned 3 5.4 powered vehicles, two 03 2v and one 3v. If I ever have any shuttering or loss of power I always check spark plugs and coils first. They’re notorious for misfiring. They’re the cheapest and easiest to diagnose in my opinion. if they pass then I move on to fuel and vacuum leaks.

    It might be worth trying swapping a new coil pack onto each cylinder. I always start with cyl 8, if it still shutters on a drive, put cyl 8s coil back on, move the brand new one over to cyl 4, if it still shutters move on to the next, rinse lather repeat. Sometimes Ill do the same thing with a new plug on cyl 8 and 4 too before moving on to the other cylinders coils. 90% of the time it’s cyl 8 or 4 for me, they collect the most moisture and foul the plug or corrode the coil.

    Just a suggestion though, I just like to eliminate the most common and easiest diagnostic first. You could easily read literature on 4.6 and 5.4 plugs and coils all day long.
     
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  9. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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  10. maanonsen

    maanonsen Junior Member

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    Roush PSD,

    THANK YOU for your valuable information and the coil pack article/comment. I will try coil pack swaps and see what that does if anything. It almost feels like a "spark" problem, which may be why it runs fine at idle. Weird thing is you would think it would spit a misfire code out or something? I may check the fuel pressure regulator again, now that you've given me the specs. anbd see what that reads.

    From there. I'll do the coils packs, and see.

    If neither of those work, I fear it might be the fuel pump, which as you stated, means dropping the tank out, major job which would have to wait till the Spring as I have no garage.

    I just assumed it was fuel related, because it happened when I ran low on fuel and found out the gas guage was incorrect. After I put gas in it, that's when it started, but hey, I've seen stranger problems, right?!

    Thanks again for your time and info! I'll let you know how I make out.

    Happy Holidays!
    Mark (maanonsen)

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