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Looses 100% power after attempt at acceleration after idling & 75% up hills
1999 Ford F-150

Looses 100% power after attempt at acceleration after idling & 75% up hills

(1999 Ford F-150)
Codes P0171 & 0174 Lean Banks 1&2, indicating vacuum leak. Changed all appropriate hoses/lines, fuel filter, air filter, Pcv and harness, changed oil, filter,changed fuel filter which was dirty but not clogged, no leak suspected at intake manifold as it was replaced. Truck ran great after having no power, but only for about 10 miles, then worse than ever. Cut out several times while driving. Shut truck off-waited few mins, started, good for a few miles, then cuts out. Dies at stop and idle. Small hole in fuel tank. Replacing tomorrow.
2 answers & 1 comment
Popular Answer
on May 30, 2015
Lean codes can also be caused by lack of fuel... Got to know how much fuel pressure it has!!.. Leave pressure test guage attached and test drive truck..Watch for excessive pressure drop, below minimum!.. Fuel Pressure speciations below:
**Engine Running PSI (28-45)**
Key On Engine Off PSI (35-45)


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Oil Leak Diagnosis
$88 - $111 Learn More
on May 30, 2015
Lean codes can also be caused by lack of fuel... Got to know how much fuel pressure it has!!.. Leave pressure test guage attached and test drive truck..Watch for excessive pressure drop, below minimum!.. Fuel Pressure speciations below:
**Engine Running PSI (28-45)**
Key On Engine Off PSI (35-45)


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on May 29, 2015
did you try changing the oxygen censors? or you can change the distributor cap and cables as well, maybe even the spark plugs.
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on May 29, 2015
forget about distributor cap and wires,cause it don't have them!and don;t change any 02 sensors either.check those vacuum lines again,bad to rot and collapse.real bad on the 5.4L.the one in the back of the intake,the elbow.copy and paste this link,and look at the picture of it.
http://www.fordf150.net/forums/viewtopic.php?f=1&t=53615

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