alright ive been pulling my hair out over this and thought id ask someone here. i have a 1992 camaro rs 3.1L auto trans. heres the cars history. replaced fuel pump 4 yrs ago, ran perfect. VATS screwd up last summer and with help from these forums i bypassed that with resistors. started and ran every time. i also did a tuneup last summer with new ign components, again ran perfect. i parked it for the winter and in the spring it ran fine for two weeks then wouldnt start. every once in a while i could get it to start and it would run fine then die as if i turned the key. this started while i was at work and to get it home i had to keep it throttled the whole way home.
now it only starts rarely and dies after a bit. when it dies the fan surges on and off, the purge solenoid clicks and i believe its the iac that vibrates. the check engine light also flashes slowly but never throws any codes.
when i crank it it produces spark and if i take the wire off a spark plug, crank the engine, then pull the spark plug i can see and smell fuel.
ive checked about everything i can think of but cant seem to find anything wrong. could the VATS be coming back to haunt me? any help with this would be greatly appreciated!

 

It sounds like you have a bad electrical connection somewhere. Almost like the battery is being disconnected/re-connected. I'd start checking good grounds and make sure connections are good and clean etc. Then....

 

Did you ever figure this out?

 

hmm this seems to shout to me "ALTERNATOR!" you might want to check the brain of the alternator (brushes, etc.)

 

still havent figured it out. its so cold that i cant spend too much time on it without freezing my fingers off. i checked all connections and grounds and they seem fine and tight. even tried disconnecting one sensor at a time then starting it to see if the computer would go off its base program but no start still. would a bad alternator do this? the battery is fully charged.

 

yea it would. ok so what you would want to do is disconnect the alternator and check the brush of it, take it to your local shop or salvage yard and ask them to remove it because you need a special tool too remove it, and if its bad you can look around for a chip from another car that would fit.

 

in my instance i had this problem in a ford escort, thot it was the head fuse and the relays/fuses but i kept wasting money until i checked the alternator. autozones reader is not good at all, i took mine there and it read fine but after i had a ffeeling it was no good so i opened it and inside was a chipped brush so i changed it and now the car runs as if it is on a shot of adrenaline (very good!)

 

replaced the alternator because it looked shot and tested bad. car acts the same and wont start. i even put in a good battery from my truck and it didnt change anything. any more suggstions? also when i was testing the ignition coil i was getting inconsistent readings and while messing with it the fan kicked on. ??? figure that one out.

 

did you check the brushes of the alternator?

 

so i finally fixed it. i was messing around making sure all wires were connected correctly and grabbed the ecm. the fan turned on when i did so so i played around with it trying to turn the fan on. when i flexed the box the fan would turn on so i flexed it and tried starting the car. it ran perfect! i let the ecm go and it immediately died. i briefly tested the connections and prom and concluded it was the ecm. got a new one for $100 and now it runs perfect.

 

Good to hear! Turns out Base91 was right about it being a bad connection after all

 

nice man, glad you got it running good as new.

 

Good catch. However, have you poked around the ecm to see if it's something simple that could be fixed? Broken solder joint, dirty connectors etc. If so you could keep as a spare or sell it.