Ok, this is the 3100 car I bought that has 150k on the engine, 90k of which were in the Fiero. It is a full 3100 swap out of a 96 grand prix, using a 91 beretta 7727 computer.

I first had the crank but no start problem, swapped the ICM with a junkyard one, and the coils with my 3800 swap ones, and it started but seamed to have a miss. I swappedthe coils back, and it will run for a short time very harshly then die. I have since swapped the plugs and wires and it is still doing the same. Then checked fuel pressure and I'd stayed constant at 41 psi even with the key off.

Oh and there are no engine codes, I am gonna replace the fuel filter and have the old ICM tested and if it is gold, put it back on.

If anybody has anything to test let me know and I will try it.

Chris

You may want to reinstall the parts that actually got it running and then try troubleshooting while it's running. Check wires from the harness, check the MAP sensor which may or may not set a code, and the location of your tach filter if it has one, an exposed wire to close to the engine caused my engine to stall due to the spark jumping the gap. Your fuel pressure seems to be fine although normal static pressure for a 3100 is about 55 psi. from what I recall. Check your oil and make sure it doesn't have water in it, these engines had an intake gasket leak problem that ruined camshaft bearings and engines. You may end up needing to try a different ecm if all else appears to be functioning properly.

id just pull the heads off and check the valve seats that has been my problem on quite a few grand ams , crank and wont start put the jump box on and start and run very rough, common with the aluminum headed 3100 , has it ever ran hot?

quote Originally posted by 454stroker: id just pull the heads off and check the valve seats that has been my problem on quite a few grand ams , crank and wont start put the jump box on and start and run very rough, common with the aluminum headed 3100 , has it ever ran hot?

Wouldn't a compression test be better first.

Not sure if it has run hot, it ran right up to just before the fan kicked on and I hit the ac to get it going and it cooled down quick, but the car has a lot of miles before I got it. I am gonna try and get to the junk yard today to grab another computer, but I am gonna put the Icm back on first and see how things go.

Chris

I swapped in another computer from the Junk yard, no promises that it is a good one though, I am gonna check compression on it and see what I find out. I am also gonna start looking for another 3100 or 3400 to put in it.


Chris