QuestionHi Harry, I've got an '83 Jimmy Sierra Classic and can't figure out what the problem is. It doesn't seem to matter if it's hot or cold, dry or wet outside, it comes and goes like a woman's perogitive. I'll be driving along the highway, or starting out from a light and something just chokes the engine. If you put it in neutral, you can goose the RPMs and the engine acts like you'd expect it to. As soon as you put it back in gear it bogs down again. Sometimes if you gear down to first and drive it at the upper limit of it's speed range it will fix the problem, but not always. I'm the second owner of the truck, the previous owner told me about the mystery and he had tried to have it fixed a couple times over the past few years of owning it, even had the carb rebuilt. It has ~114,000 km on it, runs a 305 and has highway gears in the rear end (is that a 410?). I've recently had another mechanic check it out and he couldn't figure it out either. He adjusted my carb and fixed a grounding strap on the distributor, but beyond that he didn't do what needed to be done. Your help would be very, very, very much appreciated!
Sincere thanks,
Cory
AnswerI drive diesels, but the basics are the same. You have to have air, fuel, compression, and spark. Air and compression can be ruled out in this case, since the problem comes and goes and it would not if air flow was restricted or compression was low.
That leaves fuel and spark. The ignition system needs to be checked for proper operation when the problem occurs. Most of the time, it is an ignition-related issue.
Your problem could also be fuel delivery. That means bad hose(s), line(s), fuel pump, clogged fuel filter, collapsed sock filter on the inlet in the fuel tank, etc.
There are too many possibilities to diagnose this problem over the Internet.
