it died as i was getting off the freeway. it will crank up, but runs really rough and sputters. almost like a 4 cyl with a plug wire off. this happened late last night, so i haven't had a chance to do anything with it yet, but what should i be looking for?
Check the EFI relay and it's wires around the fuse box. I believe there is/was an issue with the wires being a bit thin and a ground wire also having a problem there. The EFI relay is the likely issue. Sounds like yours is on the way out, so perhaps pulling/cleaning the contacts/reseating will get you by until you can obtain a replacement. Generally they simply go and it will not start, so I'll be curious if this turns out to be it.
Budd, buddy of mine with a 91 had this continously happen to him. Got to the point he was driving around with a bag full of relays picked up from Radio Slack. He ended up having to rebuild a good portion of his fuse box and some wiring.
If your truck has ever been dunked, you may want to plan on doing the same.
Might just start with the wires, checking resistance, then working your way back...hope it's not the ignitor, cuz' you'll be feeding all of CDan's dogs with that little jobbie...
Coming off a freeway you'll get a normal and significant heat spike as the engine's loaded with heat from the effort, then RPMs drop to idle. This is often the time a vehicle will overheat as well. So, might be a heat-related failure of an electronic component. I'd not bother with a compression check but would do the traditional sequence H noted above. If you need plug wires, I've got a set.
Ouch, time for a cyklinder leak down test to see if you can determin where the problem is, hopefully it is just a valve leaking, or something else that only requires head rework
low compression is an expensive problem. it would pay to get a professional second opinion from a mechanic who is familiar with the 3-FE AFTER you pinpoint what the problem is on your own, weather you are going to do the work yourself or pay ot have it done, if you go in there without your own research you are more likely to get screwed
I've always thought that adjacent cylinder compression problems meant a breach between the 2 in the HG. There used to be a fitting that would screw into the spark plug hole and allow you to pressurize that cylinder so you could change out the valve stem seals while the head was still on. I'd try that on one of the cylinders and then listen to the adjacent one an air leak.
I think you can put a table spoon of oil in the sparkplug hole, then redo the compression check. If it goes up dramatically it is a ring problem. If not, top end still in play. IIRC, of course.
