I just got done completely redoing my 94 F250. During the rebuild, I swapped out motors completely for one .030 over with an rv cam. We took off the egr valve and smog pump, and I made sure to cap everything. When it was done, it ran great for about a week. Then it started to go bad, eventually stopping running altogether. I replaced the fuel pressure regulator and it ran well enough to limp it to an engine shop. They started with the distributor. Helped, no fix. Fuel pressure was good. It eventually came to a new engine control unit. That did it... for awhile. Now I'm living with the constant fear of it not starting, and sometimes even dying. Today it died in the middle of the street and i barely rolled out of traffic. Sat in a side street for about 20 minutes, then it started again. I shut it down and fired it back up to make sure, got gas, fired up again, and drove 35 miles home with no problems. This is a pretty common occurrence. Any suggestions? Do coils sometimes get moody? I thought once they went, they went.

Things we've done:
New ECU
New distributor and cap and rotor
Plugs and wires a dumb amount of times
Fuel regulator
Checked grounds all around

 

coils cab get "moody" like that occasionally.... other than that i would tell you to check the distributor, but you said that was good....

 

Just a guess, but could your MAP EFI be going hay wire because of the cam.... ????

What kinda vaccum is it pulling and is it steady...?

 

We've played with the idea of a map problem. When I took it to the shop last they said it was running very rich, but the new computer fixed it. I'm a pretty big scrub on EFI. I'll do some checking on that. And I've suspected the coil before, I just didn't know if they got sick. I thought they only died.

 

Fuel PumP?

 

Was it a new distributor or a rebuilt one?
What brand distributor?

 

Fuel Pumps are fine, we checked pressure. I'm not sure about the distributor, but if it was anything like the cap that came with it, its probably not great. I pulled off the center wire and it pulled the pin out with it. I'm gonna try the map sensor and ignition coil first. Thanks for the help guys.

 

Coils can be "moody" as well as the TFI or ECU
regards
rikard

 

My guess then would be a bad PIP sensor inside the distributor.

 

Sound's like a bad PIP circuit to me as well...try a CarQuest NEW distributor, they are heat tested, about $130.-, be sure to clean the seating area so as to have a good ground...don't laugh it off, I recently installed 3 Cardone rebuilt distributors in a row, (they apparently don't heat test them) finally installing the new CarQuest for the cure. You get to keep your core, rebuild it with Ford parts, have it as a spare.

 

What about the idle air valve? I haven't had the chance to try any of these suggestions, I'm a full time student and the truck had to stay at home until she thinks about what she's done, but I think I'm gonna start with the map. And then check with the shop that did the distributor and see what kind of quality and warranty it has. Thanks for all the help.

 

Well guys, subford and Slip ford man won this round. I checked the signal from the PIP to the TFI and wasn't getting anything. I put in a Carquest distributor and she's been running like a champ since. Thanks all for the help. It really feels good that there are people out there that just wanna help other people. Thanks again.

 

Good news! happy to have helped in a small way.

 

Glad it worked out for ya, but to comment on the fella who suggested maybe your EEC didn't like the RV cam, generally speaking RV cams don't have much overlap so speed density EFI systems tolerate them just fine, and you get a few ponies to boot.

What troubles speed density EFI systems is fluctuations in vacuum, as from a lumpy/high overlap cam.

 

same thing happened to my 95, a ford motorcraft distributor cured it!! mine threw the pip sensor code fault in the computer after a couple days of doing it.