Hey everyone, I come here after months of trying to get my 1991 v6 firebird working. Hopefully someone will know what the problem is and can tell me how to fix it.

the car will start when the key is turned and then idle for a second or two before shutting off again. almost everything fuel/ignition related has been replaced, the security system removed, new injectors, new distributor, and nothing has worked. before this there was no problems with the car other than it being overdue on an oil-change from the previous owner.

i am told that the computer itself might be causing the problem, but before i pay to get it checked out/replaced, does that make any sense?

thanks very much ahead of time.

 

First impression: MASSIVE vacuum leak. Especially if the engine is running about 2-3K before it dies without anyone touching either the throttle lever or the gas pedal.

Don't know how you bypassed the VATS code in the MEMCAL, but it seems to WANT to run, so I guess you should look elsewhere besides the ECM. If there was a problem with the VATS, the engine wouldn't even ATTEMPT to start.

:edit: If everything else fails, I would find a bypass module for the VATS and see if that will work. They aren't that expensive on eBay.

 

I had this problem but it was 2 fuel injectors, check vacuum leaks as stated above and then look into electrical problems.

my 10 month old new alternator was bad in mine too when it was broke down, so it would be a bad idea to go get that checked at an auto zone/advance auto parts for free

if you dont want to get it checked at a store, just unplug it and see if it will run for a minute, before i got my injectors replaced the car would run with the alternator unplugged and no belt, but dont let it do that for long.....

goodluck!

 

where in pa are you? im near williamsport

 

also, if your looking into vacuum leaks and youve replaced your injectors, make sure that the o-rings are there not letting air in, spray carb cleaner on your upper intake gaskets, and the ends of your vacuum lines, then make sure that your throttle body is properly adjusted, mine will run funky when it gets a bit off, i take it apart and reset it every now and again.

intake manifold gaskets were a big problem with LH0 V6's, and the later 3100 series as well, so get those checked out

what information can you give us about the car? did it sit, are you building it, restoring it? whats going on with it, that would be a bit of a help too, my Camaro sat for almost 4 years and now it runs almost new

 

thanks all for the help, you've given me a list of things to check and re-check haha.

FireInMe17, the car was driven daily for about a year and a half before this problem came up. I bought it and settled for the v6 because the previous owner said it was in very good mechanical condition. was going to save up $$ and eventually put in a v8, but now its all going to fixing how it is now, haha.

 

thats what happened to me lol, i was gonna get a 350 but i needed to fix my v6 first, shouldnt have, but oh well it gets 33 on the highway so im not worried about it too much, i want some better gears to make her get up and go a bit quicker tho....

how the car doing now? figure anything out?

 

33? haha man, i hope mine does that when its back.

the motor was checked for vacuum leaks (carb cleaner spray and vacuum gauge) - all seems tight.

vats key resistor bypassed with resistor set. module is giving +/-5v signal to ECM. I Bought a bypass module off eBay too.

for the injectors as the problem, idk, it seems to be a fuel management problem. looking at the plugs, the 3 on the passenger side appear light in comparison to the rich burning appearance of the driver side. Could 3 injectors go bad within the same time period? Is there a way to confirm operation without GM diagnostic computer?

ive figured out that, even though the engine starts, runs rough and dies within about 3 seconds, if you put new plugs in it will run for 5-15 minutes. During this time it will only idle, press the gas and it dies.

If there is a way to confirm operation of the injectors and the signal to them?

 

Connect a test light between the positive battery terminal on either the battery or the alternator and check the green and blue terminals in the fuel injector harness connector (behind the A/C compressor if you have one, the harness side, not the injector side) for flashing when cranking to confirm that the ECM is grounding both banks of injectors. Then, connect the test light between the 2 pink wires in the same connector and ground with the ignition on...the light should light on both. If not, check for a blown fuse (FP/INJ1 and INJ2) in the fuse panel. If the terminals pass on the harness side for power and ground, remove the injector harness, remove the split tubing from it, and look for a broken wire.