I just got the car a few months ago and it's my first Fiero. It's a 1987 GT with the 2.8, auto tranny and about 170k miles. Engine was rebuilt about 10k miles ago.
Anyways, I was driving along and suddenly it backfired and lost power. It wouldn't go past 3k RPM without backfiring and losing power. I was a bit far from home and in the middle of nowhere so tried to baby it back. Few miles later and the engine just shut off, as if I had turned it off myself. No sudden jerks or seizing. The engine sounds like it turns over, but I could not get it to start back up. Had to be towed home.
I ended up finding a badly corroded spark plug and wire on the firewall-side of the engine. I figured that must be it, and I replaced all of the plugs and wires. I also replaced the cap and rotor. Tried starting it, engine still turns over, but it just wont start. ECM stores no error codes. Fuel pump is good and it primes. Fuel filter is almost new and is not clogged. None of the belts are broken. Battery tested good. I don't know much about distributors, but I do know that the post does spin. I took the ICM to a parts shop to test it and it was bad. I replaced the ICM. Tried starting it again and still wont start, but it now backfires after cranking it a few times. I guess that means that a buildup of fuel in the cylinders is detonating from a random spark? Or could that be something else? I looked up the firing order and the plugs are all on the correct cylinders. I replaced the ignition coil, and still nothing.
This is where my limited knowledge ends. My question is, what do I need to test for next? I'm I missing something simple? I really love this car, and I want to get it up and running for the summer. Any input would be greatly appreciated.
Great. You did ran through my initial thoughts, but I had some new thoughts: 1. Did you test the new ICM? 2. It needs fuel, air, compression and spark. Have you checked compression? 3. Pull the plugs & check for fouled, wet, etc 4. Check the timing
1. Nope, I guess it could be bad out of the box. I'll run it over to Oriellys to have it tested. 2. I have not. And I'm not sure how. I bet I could find out how online though. 3. I did pull the new plugs and I cleaned the plug cambers with brake clean and compressed air. 4. No idea how haha
Originally posted by sricka01:
When cranking, does the tach register 400RPM? If its completely dead, this is the ICM. Have you replaced the ignition coil?
Turn the key to on but don't crank it. Do you hear the fuel pump whine and build pressure? It should sound like a 2 second quite hum. You can hook a fuel gauge up to the shrader valve on the fuel rail. It should read 34-46psi. You can rent a guage from orileys.
It doesn't sound like a fuse but you might want to check that too while your at it. There is one for the fuel pump and the front and back fuel injectors in the fuse panel under the driver side vent.
If you are certain of the mechanical condition of the engine, is it possible that the distributor is/was loose causing it to come out of time? If it did, you may be able to see a mark at the base of the distributor where it was and put it back. I would also do a spark test to see if you have strong and consistent spark. Most parts stores have a spark tester. Looks like a spark plug that you can open the gap real wide. Put it on the coil wire. Have someone crank it while you watch. Also, being this was an engine replacement I would also look for broken/loose ground and power feeds in the wiring. I know it's a pain, but I would do a compression check just to rule out mechanical issues. A valve rocker could have backed off.
If all that stuff checks out, turn the crank to 6 or 8 or whatever the spec is BTDC (before top dead center) and see where the distributor rotor is pointing. If its not pointing at #1, spin it one time and check again. If it still doesn't line up, then I'd be looking at the cam timing. I've had cam chains jump teeth and throw everything out of wack.
[This message has been edited by Tuna Helper (edited 02-16-2015).]