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?
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.
December, 8, 2012 AT 2:30 AM
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.