5.4 V8 running lean

Discussion in 'Trucks and Trailers' started by jkilov, Sep 3, 2013.

  1. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    I have an unusual problem with my F250 triton V8. The engine seems a bit low on torque (can't really tell) and it started to "consume" sparkplugs every 15k miles. The plug electrodes appear white and erode quicker than usual.

    I've had a trusty mechanic check it out and it's not throwing any codes. Any idea what could be causing this?, bad lambda sensor?

    On a side note, the truck is getting good mileage.
     
  2. dieselss

    dieselss LawnSite Bronze Member
    Posts: 1,548

    A 5.4 low on torque,,,,no really c'mon.
    Consume plugs as in how?
     
  3. jbturf

    jbturf LawnSite Bronze Member
    Posts: 1,406

  4. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    Yeah, this engine has loads of torque but now it feels a bit "sleepy", can't really find a good term for it.

    I threw them away, but the plugs were white (ish) and the gap was huge. The electrodes were eaten down to almost nothing.

    It also hunts for idle on occasion and cleaning the idle control valve didn't help.

    My friend is a mechanic and he recons (based on the OBD readout) that two sensors (lambda and intake T) are about to go bad, just not enough to trip the ECU, with the cumulative effect causing the problem.

    Will take it in on Monday, hopefully it turns out good as a don't have a spare truck on hand.
     
  5. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    Update: one new sensor bought me a month of rest and away we go again.

    Now it's finally throwing codes: there's a problem with the fuel pump. Given there's more time now I'll do it myself but dropping the tank won't be easy.
     
  6. thom

    thom LawnSite Member
    Posts: 146

    What year is the truck?
    how many miles?
    how many fuel tanks?
     
    Last edited: Oct 27, 2013
  7. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    It's a 2006 model with a single tank. Now close to 280,000 miles.

    A few people have advised to check the pump electronic module before tackling the pump. Visually it looks good so I doubt that's the problem.
     
  8. thom

    thom LawnSite Member
    Posts: 146


    If the fuel filter has more then 100 thousand miles on it, I recommend replacing it. I have an 01 Chevy 2500 HD with a 6L gas.I replaced the fuel filter at 65K miles. I cut the cartridge open to inspect the element.It was plugged.

    Test the fuel pump pressure using an inline gauge. The test gauge will fit in place of the fuel filter.
     
  9. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Posts: 1,415

    The filter was replaced regularly so I'm kinda not leaning that way...

    But thanks for the tip, I will check the fuel pressure to avoid needlessly dropping the tank.

    On the side note I have removed the pump control module and holy smokes is the underside corroded. I will have to order a new part as leaving this one as is would be a poor prospect.
     
  10. thom

    thom LawnSite Member
    Posts: 146

    I haven't been under a ford truck in many years, but some of them had two fuel filters, on appeared as you might expect, the other was a canister type that didn't look lake a fuel filter.
     

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