1992 Z28 305 TPI dies after warm up
#1
1992 Z28 305 TPI dies after warm up
Hi I have a pretty frustrating problem and have looked through posts for a similar problem.
I was driving down the road and my Z28 started running rough and then died. I could not get it to fire and towed it home.
I read some posts and said: aha... must be the ICM or coil. So I replaced them and the car would fire a bit but not run.
So I said must be fuel and I replaced the fuel pump and filter. My psi showed I was getting 40 psi of fuel but as soon as the key is turned of it would drop to zero. Thinking this was a problem, I checked for an open injector. They all Ohmed out ok and I used a stethoscope to listen to them and they are all clicking away. The FPR has no fuel in it and it does hold 35-45 lbs of pressure in the system when it is running.
At this point I got the engine to fire up for the last time, I had been playing with the timing and had the brown./black wire disconnected to do the base timing. The motor was running pretty decent with an odd miss while idling.
I revved it up bit and the motor quit and I haven't been able to get it started since...fak
So the only thing left was the pickup coil in the distributor... I changed that and swapped another working ICM in at the same time. Put it back together and no go.... I sprayed Quick Start into the Throttle Body but it didn't fire at all...
This morning I will put cylinder 1 to TDC and double check that the distributor is pointing in the right direction... if no go I will take the distributor out and check for spark again. I know the injectors wont fire without the ECM, but the ICM pulse for spark drives the ECM right?
My question: What's the chance that my ECM has gone bad? Does anyone know how to test it? Someone has played with the wiring under the dash and I can't find the diagnostic port to check for codes. There is no check engine light on.
Thanks for reading my essay and any suggestions greatly appreciated
I was driving down the road and my Z28 started running rough and then died. I could not get it to fire and towed it home.
I read some posts and said: aha... must be the ICM or coil. So I replaced them and the car would fire a bit but not run.
So I said must be fuel and I replaced the fuel pump and filter. My psi showed I was getting 40 psi of fuel but as soon as the key is turned of it would drop to zero. Thinking this was a problem, I checked for an open injector. They all Ohmed out ok and I used a stethoscope to listen to them and they are all clicking away. The FPR has no fuel in it and it does hold 35-45 lbs of pressure in the system when it is running.
At this point I got the engine to fire up for the last time, I had been playing with the timing and had the brown./black wire disconnected to do the base timing. The motor was running pretty decent with an odd miss while idling.
I revved it up bit and the motor quit and I haven't been able to get it started since...fak
So the only thing left was the pickup coil in the distributor... I changed that and swapped another working ICM in at the same time. Put it back together and no go.... I sprayed Quick Start into the Throttle Body but it didn't fire at all...
This morning I will put cylinder 1 to TDC and double check that the distributor is pointing in the right direction... if no go I will take the distributor out and check for spark again. I know the injectors wont fire without the ECM, but the ICM pulse for spark drives the ECM right?
My question: What's the chance that my ECM has gone bad? Does anyone know how to test it? Someone has played with the wiring under the dash and I can't find the diagnostic port to check for codes. There is no check engine light on.
Thanks for reading my essay and any suggestions greatly appreciated
Last edited by dexxy; 09-18-2020 at 06:43 AM.
#2
Re: 1992 Z28 305 TPI dies after warm up
The problem turned out to be a shorting rotor. The guy I bought the car from had replaced the distributor with a cheap aftermarket one (red plastic).
I took the distributor out and hooked it up so that I could turn it by hand and see if there was spark. I was getting spark from the center post but not from the outside posts. So I took it apart and sure enough the rotor had a black spot on it under the contact.
I replaced it with an original gm rotor and cap I had sitting around and the car has been running great since then!
I took the distributor out and hooked it up so that I could turn it by hand and see if there was spark. I was getting spark from the center post but not from the outside posts. So I took it apart and sure enough the rotor had a black spot on it under the contact.
I replaced it with an original gm rotor and cap I had sitting around and the car has been running great since then!
Last edited by dexxy; 10-04-2020 at 08:09 AM. Reason: added picture
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