Thought I would reach out to my fellow Corvette owners to help solve this mystery. My 89 convertible runs wonderful,
however, the other day it began to run really rough to the point where it would not idle, finally stalling. When I attempted to restart, it would idle rough for a few seconds, and stall again finally causing it not start. I waited about 5 minutes, and the car restarted. When it restarted, the idle was real rough again, but this time and I able to keep it from stalling by bringing the RPM's up, then the car ran perfect again. After this episode, I took it on a 30 mile run with no problems. Had it out two other times since, no problems.

Just a couple of thoughts and other things worth mentioning...

1. Unfortunately, I have only had the opportunity to drive it about 225 miles this year, therefore the gas that is in the car is from when I put it in storage last November. I did add Stabil in the gas when I stored it for the winter, but at this point I am sure it has, or is beginning to breakdown.

2. Due to the fuel being old, I thought that it may have caused deposits on an injector or two which may have caused it to misfire and stall.

3. Could it be that the fuel pump is beginning to fail?

As good as the car has always run, reliability concerns are now lingering in the back of my head every time I drive it.

Your thoughts and feedback are much appreciated!

 

How many miles on her? Could be your fuel filter or bad injectors!

When's the last time you tuned her up? Plugs, wires, fuel filter, rotor and cap?

I would drain that bad fuel out and fill her up with new premium fuel, then test your fuel pressure and injectors first to eliminate fuel problems, otherwise you may have an electrical issue of some sort!

 

I would check the IAC under the TB. Passages could have a carbon build up and the IAC itself could have gone bad.

replace fuel filter. Check condition of plugs.

Any codes showing?

 

In winter I pour Gas Dry, Stabil or Seafoam to stabilize the gas and go with that. In spring, I run it till it is almost empty and out fresh gas in it. I change plugs, oil and filter, misc fluids. Also clean out the IAC passages including the IAC housing and wipe off the IAC. If it is the 3rd year after I cleaned and tested the injectors, those go to FIC or someplace like that.

 

Checking out the IAC is indeed on the right track but since it was stored for a while check out all the vacuum lines too. Especially the PCV hoses and brake booster hoses. A PCV system leak can cause erratic idle and stalling.

I think the 89 has MAF too and it should be clean with no splits or cracks in the ducting between the MAF and TB.

 

Has 81,000 on her. Injectors were replaced about three years ago. Tune up was done about the same time. Car has been driven about 1600 miles since. No codes showing as of yet. Cleaning the TB is something I should do as well.
I should just replace the fuel filter, IAC, and check for cracks in the MAF. Fuel pressure test is a good recommendation as well. Will an IAC fail intermittently, or
just fail?
Thank you...I really appreciate all of your feedback!

 

Yes I would do that as a yearly thing.

If you haven't, why not do it now?

I wouldn't throw parts and hope it works

Any leakage from the MAF to the cylinder heads and all the hoses. Use an UNLIT propane torch.

Needs to be able to get it to 43 at least and hold for a while with a little drop.

It could but I wouldn't go there YET.