My 2002 F150 has been acting kind of strange and I guess it's time to address it. I've got 115k on it and it has been taken care of since I purchased it in 2004. Lately I've been having trouble getting it to crank / fire up at random times. It will turn over fast and fine but just won't crank. Normally I turn the key for about 1 second and it's running however, at times, I'll hold it down for 3 - 5 seconds and all it does is turn over. I'll stop, wait a sec, hit it again and it will fire up. It has never done this first thing in the a.m., it's always in the afternoon or in the evening when I need to crank again and engine isn't cold yet. Might just be coincidence but that seemed a little strange that it only seems too happen when engine is warm. Most recent instance was last night after football practice. Truck had been parked for about 2 hours, went to fire it up and leave but engine would only turn over. Eventually got it cranked. Once cranked, the idle is perfect, no misfire while running, no lack of power. Within the past year I've replaced fuel filter, plugs, and COPS. Not blowing any kind of smoke and I always run techron gas. I add additional techron additive about 3 or 4 times per year.

Any ideas where too start?


Thanks,
Chris

 

First, turning over and cranking are one and the same thing.
You really mean cranks but no start.
I would check out the fuel pressure to see that it's right there when cranking begins. Should see about 35 psi with a gauge.
Next reseat the crank sensor up behind the A/C compressor.
Next is the Theft light is blinking when there is a failure to start?
Check seating of the relays in the engine bay fuse box.
Good luck.

 

Cranks but does not start right away, you are correct. Fuel pressure is good and no theft light flashing. Someone else suggested checking the crank shaft position sensor as well. Is this something I should troubleshoot or should I just replace the sensor? I think it's around $30 and the current one is 12 yrs old...

Thanks for the input

Chris

 

Crank sensor hardly ever goes faulty, I would just reseat the plug. It's your call.
A no start is either no spark, no fuel, or both so look at it from that point.
See which it is and pursue that direction.
Issue with crank sensor would cause both failures.
Intermittent PCM relay would case both to fail ect.
Intermittent fuel pump relay, only the loss of fuel. Check for good reset of crash sensor behind the pass kick panel.
You have to get a lead on it to go with.
Good luck.

 

I'll start by re-seating current sensor and applying some dielectric grease while I've got it out. It's going to be difficult to get a lead on since the problem is so sporadic, hopefully re-seating sensor handles it. I'll move to relays after that.

Thanks again.

Chris