1995 Ford F-150 Stalls while driving, won't restart 10 minutes?

Hooked up computer...no diagnostic codes. No check Engine light. Computer did indicate that it might be running rich. Changed TFI module, replaced fuel filter, changed plugs, wires, distributor cap, rotor, air filter, changed pcv valve, has two fuel pumps (two tanks) and same symptoms either tank. EGR holding vaccuum ok. Truck stalls intermittently but with increasing frequency. Also ran Berryman's cleaner through tanks. Occasionally it won't start from cold, but wait 30 minutes it stars okay. More often it dies when warm and driving, leaving me stranded in the highway. 10 to 15 minutes later it starts, drives fine. Engine is running fine no roughness or sputter. This problem has been going for weeks, driving me crazy. This is a 1995 Ford F150 with 5.0L (302). Suspicions: fuel pressure regulator, ignition coil, camshaft position sensor, pef sensor. Do these symptoms seem to point to anything or to additional tests I should do? Thanks very much!

Additional Details


<SMALL>14 hours ago</SMALL>
Couldn't get it to fail this afternoon. After trying, I finally just took the hoses loose and spray cleaned the throttle body. Drove more, still couldn't get it to fail. Tomorrow morning it will fail. I'm ready with a fuel pressure guage and a spark plug tester and a bag of ice to test it out when it fails, any other suggestions?

<SMALL>13 minutes ago</SMALL>
Well, it didn't stall this morning. It is just evading my attempts to diagnose it.

 

Sounds electrical. The truck runs fine but just quits like you hit the kill switch.. right? Could be the EEC power relay or fuel pump relay. If you had a fuel pressure gauge on it you could see if the fuel pressure drops just before it dies. But then, when it quits if you hear the pumps cycyle when attempting to restart then that would seem to eliminate that. Could also be the computer itself is dying...

 

Although the pumps cycle up on restart attempt, it usually has to set about 10 minutes before it will successfully restart. You are correct, it dies just like a kill switch...no warning, just stalls.

When does the EEC relay or fuel pump relay engage and why would they fail after 10 to 20 minutes of driving?

I got a spark tester and a fuel pressure guage in the truck so I can hook up next time it fails and determine during the hard start time if it gets spark and fuel.

Thanks!

 

I checked the ECT (coolant temperature sensor) while engine was cold...got about 18K ohms. Is that appropriate?

 

Besides the fact that the truck is warm when it gets around to stalling, it also tends to experience the stall about the time it starts downhill or coasts.

Runs fine most of the time, just intermittently stalls on downhill, and then is hard or impossible to start but after it rests several minutes, starts up fine runs fine.

 

I'm not getting hard nor soft codes from the failure...does this eliminate sensors as a likely culprit? Such as the ECT, TPS and so on? I think it eliminates egr system, too. So looking at something like ignition coil or fuel pressure regulator?

 

If she stalls going downhill or coasting does it start to buck a little before it stalls.Try this if you have the problem and it won,t start. Remove the idle air motor and see if it starts. You have to open the throttle a bit but if she starts its the IAC. I have had similar intermittant problems with the IAC .Your ECT at 18 k at room temp sounds ok and when hot aound 195 F s/be around 2,800 ohms. I will post more information later . I am off to work.

 

Okay, will unplug the IACV next time.

However it didn't die yesterday or today. That's not typical, it was dying pretty consistently. Here's what changed since the last stall: changed to high octane fuel 92 vs. 87, spray cleaned the throttle body, outside ambient temperatures are a bit cooler the last couple of days. It still feels like it gets close to stalling on an occasional down-hill, so maybe I can tinker with the IACV and see.

I'll test the ECT for 2.8k ohms at hot, too, thanks for the good info Missaugaua.

David

 

This one sounds like the PIP sensor (cam pos. sensor) in the distributor is bad.

 

Hi subford, wouldn't a bad Cam Pos Sensor throw a diagnostic code? How can it be tested to prove it is good? Would a bad cam pos sensor be this intermittent?

 

NO If it opens from heat or vibration it would a little hard to test. I would say replace it would be the best way. You could try an ohmmeter with a heat gun or shake the wires. YES

 

I had problem when coasting and on a downslope . It felt as if I was running out of gas as the truck would start bucking as if I was hitting the throttle and releasing it real quick. It was getting hard to start intermitantly and finally I got a no start situation.On a hunch , I REMOVED the IAC from the throttle body and the truck started up .(got lucky) When I checked the IAC it was shorted out.Replaced with new one and was ok. After you mentioned it was acting up on coast and downhill it seemed very similar to my situation. Thought I would pass the information along.

 

mississauga: thanks for the info. Okay, so just unplugging the IAC won't do it, I need to take it off to test theory. got it. I'll try that! That's two or three people suggesting that part, so it's an easy test, it's my next step along with checking pressure and spark next time it stalls. Then if not that, then trying what subford says about the cam pos sensor. Thanks! I'll post results...

 

It is worth a try.Doesn't cost anything. It is a bit of a short cut approach but you never know.Try and figure out the problem before you start throwing the parts at it. Subford is a knowledgable guy and knows these trucks inside out.

 

You may have a bad pickup coil, aka distributor stator assembly. My truck had the same problem. Ran fine driving down the road, then dies. No codes, nothing. Wait about 10 to 20 minutes (stator cool down?) and the truck started. This got progressively worse until the part finally failed.