Hot restart problem with 92 LT1

[Jim Martley]

I am trying to track down a problem for a friend of mine. The car is a 61,000 mile 92 LT1 6 speed convertible. Car starts fine when cold. Run the car for 15-20 minutes and shut it off. 4 out of 5 times the car will just crank over and will not run. Let it sit for 5 to 15 minutes and it will start & run!

I have checked the fuel pressure and it is 37 to 45 lbs and holds steady when shut off.

There is spark from the coil.

There is NO black smoke when it restarts.

I also checked the resistance of the injectors hot & cold. They were 11.2 ohms cold and 12.6 hot. All were within .1 ohm of each other.

I DID find that the injectors were NOT getting a signal when the car wouldn't run.

There is also an intermittant flash of the "SYS" light and "Security" light when the car is running and it will sometimes have the "Service ASR" light come on.

Any ideas?
__________________

 

[6speeder]

....... I DID find that the injectors were NOT getting a signal when the car wouldn't run.

There is also an intermittant flash of the "SYS" light and "Security" light when the car is running and it will sometimes have the "Service ASR" light come on....

Any codes?

http://www.chevythunder.com/ses_chart_a3a.htm

 

[Jim Martley]

I did not get any codes out of the ECM.

I am finding out now that there may be codes in the CCM but I don't know how to get them. Any ideas on how to access those codes without a scanner? I have an older model "AutoXray" brand scanner that I have used for the OBD1 systems for years but it doesn't work for the CCM diagnostics.

 

[6speeder]

open this link, scroll down and you will see instructions for grounding A & G to access CCM:

http://corvettebuyers.com/c4vettes/codes.htm

 

[Jim Martley]

THANKS!!!!!!!!!!

Where do I find what the codes mean? I have a 1993 GM service manual but I am not sure the code are the same as the 92 I am working on.

 

[6speeder]

92-93 are the same....

 

[Jim Martley]

I'll check for the CCM codes when I get home.

Thanks so much for all the help!!!!!!!!!!!!!

 

[6speeder]

This link was included as an 'edit' in my first response; you may have missed it: http://www.chevythunder.com/ses_chart_a3a.htm

You might check the ignition module.... it is readily accessible... can cause a "no-start-when-hot" condition. Good luck!

 

[Jim Martley]

You might check the ignition module.... it is readily accessible... can cause a "no-start-when-hot" condition. Good luck!

One of the first things I checked was "am I getting spark?" as we ALL know how much fun the Opti-Spark system can be!! I have even gone as far as putting a heat gun on it when the engine is stone cold to see if it had any affect on the cold start operation. The car starts fine when started "cold".

 

[John Robinson]

Similar Problem

I had a problem with ghost codes and finally the car quit running. I had it taken to a garage to do diagnostics on it. Like you I did not get any codes from the ecm. Also like you there was no signal to the injectors. ECM is bad. If you end up looking for an ECM good luck. I called all the Corvette parts houses I have catalogs for and they either did not carry them any more or they have been on back order since Nov. with a promise of maybe June. I did find one place that would send my core in for rebuild with about a 3 week turn around time. Fortunately the garage mechanic had some friends at the AC Delco distributor. He was able to go through them as car was down and they were able to do a national search and found one at a dealer 100 miles from me. I am waiting on paper work to release it from the dealer to the regional distribution center for AC Delco and then they will forward the part to my AC Delco dealer. I even offered to ride my motorcycle the 100 miles to pick up the part but they can't sell it direct to me. Everybody gets their markup and I stand at there counter tying my shoes with them behind me. So if you are sure it is the ECM start looking now and be persistant and patient.

 

[Jim Martley]

John,
This car has a new computer on it already. I am not sure if this was installed to address the problem it has now or another problem in the past. I will ask the owner when I call him tonight.

Thanks for resopnding,
Jim

 

[Tuna]

I had a similar issue with an LT4 car but it turned out to be the check valve holding fuel pressure was not working. The fuel pressure would fall right to zero after shutoff and it caused a hot start problem.

But you say that fuel pressure in this car is holding after shut off, so that's probably not it.

Hope you find it soon.