97 and 98's had a issue with the primary starter wire ( large red wire)corroding inside where it was not visible. My 97 went bad and drove me nuts trying to find the problem. Sometimes it would start right up other times it wouldn't do anything. This was a known problem. However I think you are getting some different symptoms. Just an idea....

 

Was your issue with the starter not functioning? My starter is new and when I hit the key it turns over perfectly. I should have mentioned that before.
Talked to my friend that wrenches at ford and were stuck.
It has proper fuel pressure at the rail.
Starter turns over.
Sometimes when it wont start the fuel pump runs constantly, sometimes it primes and turns off like normal and still wont start.

 

A 98 F150 shouldn't have PATS.

You might want to replace the PCM power relay.

 

The fuel pump not shutting off could possibly be a computer problem. That is one weird
truck. sorry i couldn't be more help. I'm curious as to what the fix is. keep us updated.

 

Going on the garage for exploratory surgury tonight. Ill post any results. Keep the suggestions coming though.

 

Ok, I went over every vacuum line, every wire,relay and every fuse and no visible issues. But, tonight it ran for an hour and a half and 15 miles of driving. The issue would not show itself tonight. I couldnt get it to duplicate the problem. See, no consistency. Is it possible that the PCM is failing at random? Ill post more when it happens again and I get new results. Im sure it will do it again shortly.

 

Seriously, replace the relay.... They can get flaky and cause all kinds of power fluctuations to the PCM.

 

OK, so I got a new PCM and fuel pump relay and they are in. Worth a shot for as cheap as they are. Ill keep it updated.

 

Back to the drawing board. After replacing the IAC, and relays all was well for 100 miles or so. Drove to Menards and a few other places and as I was just about to pull into my driveway, it stalled at 25 MPH. Turned the key off and on a few times while coasting and it started right up. Got home and turned it off. We went back after a half hour and it would not start, turns over just no fire in the cylinders. So I turned the key off and on about 5-10 times within 10 seconds and boom, fires up just fine. Then I drove it to work yesterday, 30 miles in and 30 miles home without a stall, but as soon as I parked the truck it stalled right in the driveway in park. Tried to restart it and again, cranks fine, fuel pump primes but no fire. Turned the key off and on again about 5-10 times in a few seconds and fires right up. What the hell? Any new thoughts?

 

Just a thought, is it possible that everytime I pull the fuse or disconnect power to ECM it runs perfect for about 100 miles, then stalls like an a$$hole?
Could it be that the PCM is in learn mode for a few drive cycles after reseting then once the ECM takes over, something in the ECM fails. And with me turning the key off and on repeatedly be reseting the ECM somehow to enable it to start? Anyone know how to verify a failing ECM?

 

Update:
I spent my entire evening (two hours in the garage idling, fun right?) plugged into the ECM, watching the PID information and falling into a mindless trance when finally it happened!! It stalled on camera, awesome!! So here is the data in the last wee moments prior to the stall, translated ....

First sensor to stop reporting to the PCM was the engine coolant temp sender (idle changes, goes from perfect idel to a slight shudder in the idle)

then 67 seconds later the intake air temp sensor stops reporting

800 seconds after the throttle position stops reporting

1 second later the timing advance stops reporting (cam/crank sensors go offline)

then according to my recorded data 2 seconds pass then it stalled. But, now the data link is dropped. KOER becomes KOEO, cannot reconnect, man down!!!

So I turn off the ignition and turn back on KOEO and reconnect. It connected just fine, so I turned the key to start and it starts right up.

So, does everyone agree that we have a bad ECM, Engine Control Module, commmmpuuuuuterrrrrrr ???????????????

 

Ladies and gentlemen, we have a fix: See

https://www.f150online.com/forums/19...ssistance.html

 

Was unable to open the link can you please tell me what fixed your truck

 

I know this is an old post, but I read in another thread somewhere that some folks who had similar issues discovered that the trouble was due to another vehicle key on their keychain with a chip in it-- the proximity of the wrong key to the ignition caused confusion and triggered the anti-theft... Just a thought, for anyone else who might stumble onto this thread with similar questions.