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Howdy all,
1998 5.4 Eddie Bauer, 225k
Lately been suffering some rather severe hesitation/sluggishness on acceleration (bottom of the power band), then smooths out. Happens on acceleration from standing start, from acceleration at road speed, as well as at highway speed.
This only happens upon restart after truck has been sitting for an hour or less. Runs perfectly on initial start/drive or after it's been sitting for a few hours.
Truck never stalls out, but acceleration is quite challenged.
It was suggested that perhaps "bad gas" but several tank fills and bottles of conditioner and gas line anti freeze has not resolved.
Fuel filter was changed 7 months ago. Plugs and COPs are a year old.
No idiot lights on dash.
Any suggestions are greatly appreciated.
Ford fuel injectors, need at least 45lbs of fuel pressure. I have been told 40lbs or below will affect how it runs.My guess is a failing fuel pump. Do a fuel pressure test. When these pumps age, they don't always go out all at once, some do. What happens to some is they do exactly what your describing. Kinda like a human that has a failing or clogged heart. We keep on going but labor to do so, especially when our bodies get loaded, like walking uphill, or trying to lift something. If your pumps failing, instead of pumping the necessary 35-55 psi, it drops down to 10-25 psi. Enough to fire and run, but labors under load. Check pressure and report your findings.
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Question do you notice this happen when engine is warmed up?
I'm asking because I have had this problem for a long time now and have tried all of the things listed above when engine is cold it runs great. There is a Ford TSB out that talks about it but it requires a re flash from ford