ok.. so, i have a L98 90 GTA i have replaced the fuel pump and now the car will start and run and if you pull it out on the road and floor it it will go and just b4 it hits 2nd she dies it`s like you turned the key off and if you let it idle in the drive way it`ll start stumbling and running rough untill it dies and then it`s a pain to get it started again and if you get it started it wont run long and will die again and will not start after that... my fuel pump runs at 44 psi and holds it even when the car dies until the relay shuts the pump off then it`ll drop to 34. i even drove the car as much as i could with the gauge hooked up and when it died the gauge read 44 psi so my pump is fine. i also pulled the coil wire off to check spark when it wouldn`t start and it has spark so thats good too, so i checked to see if the computer had any codes NOTHING... i don`t know whats wrong with this thing.

 

My gut reaction from what you describe would be the ignition switch or module. I would need more info. In the no start condition, are you getting 12 V power to the distributor? It could be an injector issue as well. Your fuel delivery at least to the rails seems ok. It could be possible you don't have a strong enough spark as well. When you are flooring the car, there is lots of turbulence in the cylanders, and if spark is weak, it could easily die. If your plugs/wires and the like easy stuff are real old, I'd check into that as well. You can start elliminating things by doing easy tests, like ohm testing your injectors, getting a volt reading at the distributor (takes away half of the ignition system), noid testing the injectors. I'm armed with a service manual for a 1989 GTA, the set-up is pretty identical to a 1990 as GM was switching to a bigger change in the 1991 model run. Does it seem to fire up easily when cold and have all it's problems when it's been run? Don't forget compression, as it's the last of the big 3 you need to have a properly running motor. Lay down all you know, that will help!

 

ok.. the plugs, wires, cap and rotor are all brand new there about 2 months old. i havn`t checked to see if theres 12 V to the distributor yet and i don`t have a noid light, but i`ll check to see if there 12 V to the distributor and test the ohm`s on the injectors tonight after work.

When the car is cold it`ll fire up right away with no problem, and if you drive it sanely it`ll be alright for about 10 mins then it`ll start stumbling and die... if you let her sit after it dies for about 4-5 hours, it`ll start back up like nothing was wrong.

As for the compression test i havn`t done that yet, if we can`t get the car running fine by the weekend, i`ll do that on the weekend, i just don`t really want to because it`s such a pain in the *** getting to the plugs on a TPI car. and i`ll cry if the engine itself is bad. i`ve spend so much money on this thing, i can`t afford an engine rebuild, even if i do it myself.

 

If it runs fine for any length of time, I'll bet your engine is physically okay. Stranger things have happened, though.

Ignition module is my guess as well. The "starts when cold, runs good for 10 minutes" is classic. I can't tell you how many times I've heard that line and it was the igntion module. It's the weak link in your ignition, and as they get hot, the rpm signal starts to flutter until it's useless. If your tach is real bouncy when it starts to go bad, I'm absolutly sure that is at least part of the problem.

Solution: Get a nice module(avoid the dirt-cheap chinese crap), install it with actual heat-sink grease(not the clear die-electric crap), and maybe even get new connectors for your harness. If you even spit on those connectors when they are bad, it'll short out and kill those modules damn fast. I'm only slightly exaggerating that.

 

ok... i got the light to test spark, so i hooked it up and the car was running fine so i kept reving the hell outta the engine and it died just like i knew it would... well heres the kicker, my fuel gauge said 44 psi and the light was flashing like crazy even though the engine died..... if the module is bad wouldn`t the spark stop if the module went bad???

and as i was typing this i had the car running and it just died again.

 

When the car dies... Does the tach go to zero instantly even though the engine is still turning? Watch for any tach irregularities.

 

hey... i think it`s a bad computer

it has fuel pressure and spark.. i disconnected the 1st cylinder injector plug and hooked up a test light to see if it would pluse and it doesn`t and my car will not start right now

 

It may not be. If the computer isnt getting refernce pulses from the distributor it won't fire the injectors or run the fuel pump....

You need to figure out whether or not the computer is getting the pulses.

 

well i know the fuel pump runs even when the engine dies because i have the gauge hooked up to the fuel rail and you can hear the pump running even after the engine dies till the relay shuts the pump off

the car has spark i had the light hooked up to the 1 st cylinder wire and the light was flashing as the engine died i watched it... so i know the module is fine because not once did the car not have spark.

the final reason i think the computer is dead is because i pulled it out and it was really hot which explains the problem of the car running fine when it`s cold and not running went it starts warming up... so everything is working fine when the computer is cold once it heats up the injector motor in the computer stops working. heance why i have spark and fuel but the fuel isn`t getting to the cylinders.

so i know the module is good, because i have spark and if your module is bad you won`t have spark at all, and i have fuel just it`s not getting to the cylinders and the computer gets really hot which means theres probly a short in the computer, most likey in the circuit that runs the injectors

 

Hmm.


Ohm out your injectors. If there are several which are too low, they will overheat the injector drivers and they will shut down.

 

ok i`ll do that tommorrow... i did ohm the 1st one and it read 14 but it kept jumping around from 11 to 15 ohms

whats the ohms they should test at?... i think it`s 14.5??? but i`m not sure.

 

ya. They should all be 14-16.

 

well it`s the injector.. EVERYONE OF THEM IS BAD

heres how they tested

1. 9.8
2. 8.7
3. 17.7
4. 17.1
5. 9.8
6. 16.9
7. 17.6
8. 17.0

so now i gotta buy 8 injectors and there 50 to 200 bucks APIECE

so i`m looking at min. of 400 to get my car running.

 

I wouldnt be worried about the 16 and 17 ones.

 

really.. wouldn`t they have too much resistance??? i figured it`d be better to replace them all... BUT if i really only have to replace 3 that`d be ALOT better.

 

Updates?

 

Toehead is correct. These cars should ideally have injectors that ohm out at 16 plus. I'd bet if you changed out the 3 bad ones (my recommendation is to drop the coin and replace all 8) your problems would go away. 3 bad injectors could easily cause the symptoms you describe. A cooler engine likes lots of gas, a warmer engine does not. 3 bad injectors could easily be allowing too much fuel into your cylanders.