Hi guys!

I have a 1994 F-150 4.9L 5-speed manual. I bought it new. It has about 99k miles on it.

Lately it has an intermittent problem. Sometimes it will just crank and not start. After a couple of attempts it will start, no problem.

Sometimes it will just die when I am driving it. This usually happens when sitting at a light, or just after leaving a light.

No check engine light. However, sometimes (when I start the truck after it has been sitting) the airbag light will flash 3 times, then wait then flash 3 times again. It will keep doing that until I turn off the truck. It might come back right away, it might stay off for a couple of weeks.

Originally I replaced the plugs, cap, rotor, air and fuel filter. But it did not fix the problem.

Also, I think I need a new fan clutch, because in the summer, sitting in traffic, the truck gets hot. But after I start moving, it cools back down. That's been going on for about 2 years. I need to fix that.

I may have two problems. Could I have a faulty fuel pump relay and a bad IAC valve? Do I have an IAC?

I would appreciate any help!!!

 

Hey Jesterdog
I hear you about the stalling problem. I am searching for answers to my stalling/dead truck issue as well. I bought ( another manual) the Haynes and it has some good troubleshooting stuff in there.
Alot of mechanics will shoot a small amount of starting fluid to see if you got a fuel or spark problem. If it wont light up, have an extra spark plug on hand, some spark plug wire pulling pliers and a way to ground the plug. Be sure its in nuetral and hit the starter solenoid with a screwdriver to see if you got spark. Dont use too much starter fluid.

I still have not purchased a fuel pressure tester to chech mine.

After years of no overheating issues I finally traced the tiny leakage and overheating to replacing the water pump and the fan clutch at the same time, problem solved. It may be safe to say that any vehicle over 15 years could use a water pump. My 84 Toyota truck blew a water pump 500 miles from home last summer near Reno, I was on the way to the Hot August Nights car show.
Good luck

 

Jester
I forgot to mention that Autozone will rent you a special wrench to remove the fan. If you buy one it costs $40 or so. Unless you have access to some big wrenches.

 

When it happened today (at the same light no doubt), I turned the key and it cranked but would not start. Then I turned the key off, then turned it on and to start (like normal) and it fired right up. I wonder why I had to kill the power for it to work? Can a fuel pump relay quit working while it is running? This happens on either gas tank. So, two different fuel pumps.

 

Jester
Thats the same routine I went through. Did it one time a year ago, 20 miles after I filled up with Mexican gas one year ago. Truck stalled I switched gas tanks and it re-started. Did not give me a problem untill a month ago. Then I changed gas filter last month, no change.
Its cheap to replace the relay but to diagnose it you would have to be looking at a voltmeter hooked up to it right when it dies.
My 92 4.9L started acting like it was running out of fuel last month on the way home from work. It would die, I would change tanks and it would restart. Untill I drove up the drive way and died. I may just buy the fuel pressure tester and see what it says but my truck is still dead with spark and starter fluid will not work.
One short story about relay's, years ago I bought a dead '86 ranger. Took weeks to diagnose it with my knowlege. Would turn over but no start. I found I had no power to the computer, no ref voltage. went to change the relay to the computer and out of the plastic 4 wire connector pops a wire. That wire was just loose enough to look normal but when I pushed it back into the plastic connector the truck started up and never looked back. The relay was good but the stupid wire connector was the defect.
By the way thats the first thing I checked was the ref voltage on this F150, the computer works because I have ref voltage at the appropriate sensors.
Let me know if you find the problem. I searched the archives and guys that had this type of issue did not post the fix.

 

Well, week before last, it just died...And this time it would not start for anything. So, called the wrecker and had it towed up the road to a shop that I had used in the past. I figured that it was dead, they'll hook it up to the computer and find the problem and replace the bad part.

Well, it went back to starting most of the time. Anyway, they couldn't nail it down, so I had them replace the hall effect sensor in the distributor.

I need to have them readjust my timing because it's a little retarded and down on power (I should back up and say that when I picked it up it knocked and pinged on the way home. They accidentally set the timing wrong-too far advanced). So, I need to have them bump the timing up a little.

Which reminds me. There is no procedure for setting the timing in my Haynes manual. I have EFI and apparently you have to put a jumper plug on the harness to set base timing?

Anybody know how to do that?

If it comes back I think I'll replace the ignition module...any thoughts on that?

Anyhoo, I'm still driving it to see if the problem comes back.

Just wanted to report in...