2005 Ford F 250 M Working On 4 Wheel Drive 5 4l 3v Gas Engine Occasion Will

2005 FORD F-250
125,000 MILES
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THOMASNCHY
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I'm working on a 2005 Ford F-250 4 wheel drive with 5.4L 3v gas engine. On occasion it will not start, it will crank over fine but not start. Usually after 2 or three key-off, key-on sequences it starts. More often than not it will start first time.
I have replaced the fuel filter, fuel pump, and pump driver. I listened to the bottom of the tank while a friend cycled the ignition to "on" and the pump was ...."On'.."On".."On"..off..off."On".."On".....etc. no rhyme or reason. My next point of attack is the crankshaft position sensor.. unless someone has a better idea?

Thanks
Dec 8, 2012 at 2:02 AM
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ASEMASTER6371
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what is the fuel pressure???

Roy
Dec 8, 2012 at 2:04 AM
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THOMASNCHY
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I was only able to read it with my scanner at idle and it was @40psi, after I replaced the pump. I havent hooked it back up since I installed the driver.
Dec 8, 2012 at 2:19 AM
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THOMASNCHY
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When the pump cycled to "on" I had him go ahead and start the truck and it ran fine at idle and wot. When I didn't here the pump kick on the truck (of course) would start but die shortly- maybe 5-6 seconds rough idle.
Dec 8, 2012 at 2:30 AM
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