bout-time

I have a 1992 Corvette. The engine dies randomly but I am always able to restart it. No hesitation or anything, it just cuts out like someone turned the key off. This happens when driving, and if just sitting in driveway running. No trouble codes in the ECM. I did replace the Opti-Spark wire harness since the plastic connector tab was broken, but this made no difference. Only thing I am thinking at this point is the ECM or Opti could be the culprit. If Opti was failing, wouldn't it cause a code(s) in the ECM? When the car cuts off, I'll turn the key to bump the starter and do not get a fuel pump run until like the 7th or 8th bump. This leads me to believe it's the Opti, but again no codes are present in the computer. Any help and suggestions are greatly appreciated. Thanks.

bout-time

Has anyone experienced any similar issue to this? Thanks.

JimLentz

Just turning the key to run should cause the pump to run for 2 seconds and does not depend on the Opti. Do you have a fuel pressure gauge?

WW7

Could be a bad "ignition control module", it's what they do when going bad...WW

TorchTarga94

MatthewMiller

I'm not sure the fuel pump is an indicator of the opti going bad. If the opti sensor goes bad, the fuel injectors will not fire. So you could put a noid light on one injector and see if it's getting a signal when you crank the engine. Also, what is the tach doing when this happens? If the opti sensor goes bad you also lose the signal to the tach. Also check that you're getting spark to the plugs when this happens.

I was going to suggest the ICM, too, until I saw the bit about the fuel pump not seeming to work. If everything still has electrical power when this happens, maybe you're losing the fuel pump itself?

TorchTarga94

Need to get a fuel pressure gauge on her and see what happens when symptom presents itself. Also need to keep an eye on the tach needle when the symptom presents itself. Does it happen after shes a little hot?

The opti doesn't always throw a code. Since you say its like someone "turned the key off", I am going to venture out and say its not a fuel related issue, as if it was a dying pump it would probably diesel to a stop. If it just cuts off instantly, probably an ignition issue. But, tests need to be performed first.

Mike Kamholz

I have an 88 I know it’s a little different but mine was doing the same thing it was the ignition control module not sure if that’s what yours is but it wasn’t easy and cheap fix.

WW7

He says the car starts right back up after shutting off... Like you said , if it was fuel related, not only would it sputter and miss before stopping , but it would be hard to start after it shut off with no fuel left in the rails..If the fuel pump had to refill the rails he would hear the pump running for sure....WW
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Huey3

I have a similar problem. I was driving my 92 convertible last week. I started the car and the "Low Oil Light" was on but the oil level was correct so I continued on the way to the store. Unfortunately I made it only 1/2 mile and the engine died at a stop sign when I stepped on the gas it sputtered twice and died and would not restart. I tried to start the car the next day and it ran fine around the neighbor hood. I got back in the car to go the store again and after I started the engine it sputtered and died again but would restart in 2 to 3 hours. However, there are no codes as to why the engine quite. But I do get an intermittent code H43 but have not had the time to follow the trouble shooting procedures. There also was not a code 43 set when the engine died.

DUB

I have to agree with ALL of the suggestions and advice.

I have oddly enough had to put on three Opti-spark distributors recently.

All of them were the early design that did not have the venting system Gm added to the later design to aid in removing the ozone out of the distributor.

I assume that you have looked at your coil wire at the ignition coil and verify that it is good and the terminal of the coil is not corroded or the wire clip inside the boot is not damaged/corroded. I have pulled some off of the coil to only find a total catastrophe.

I have also seen the heat soak plate where your ignition module is located is all filled up with grease and crap and can not aid it in gettign rid of the heat in order to help your ignition module.

When I get cars in like this..I will hook up my scanner and fuel pressure gauge and wait for it to fail. Test for spark at the plug wire like previously mentioned along with in a injector pulse.

DUB

mixalive

The fuel filter is the first thing I check when the LT1 is dieing with fuel issue. Ethanol in the fuel attracts moisture from the air. It will attract as much moisture as is ethanol. It gets hung up in the filter which is at the lowest point of the fuel system. If moisture circulates through the filter to the rails, of course the engine will die. While the engine is not running, the moisture will settle back to the filter. It creates an intermittent dieing situation. And the fuel pump turns off when it dies. Check the filter. If it has any moisture, replace it and at least blow the lines to and from the fuel rails and tank. And maybe even clean the tank.

mixalive

The opti has to maintain the hi res and low res signal. You can check it with a 2 channel oscilloscope. If I remember correctly, the LT1 will run on low res only but is somewhat unstable. They call it, running on limp mode. Oil or moisture drawn into the opti can cause an intermittent situation. And codes may or may not be thrown.

DUB

For what this is worth:

I do AGREE that the fuel filter is a very important part of the fuel system. Fuel QUALITY is also very important.

But as described by 'bout-time'. The engine dies and will crank back up. And there is no hesitation or anything.

So knowing that it was described that it was like someone turned the key off. I am still in the belief that it is electrical and not fuel related ....due to no hesitation or anything.

Bad fuel will not just shut a car off like you turned the key off...if it is running fine with no issues. If it is bad fuel it will stammer and shudder and then die.

I have had some Corvettes that had 3-5 gallons of water in the fuel tank and it would not crank up at all. Because the filter sock attached to the fuel pump is now under water and water is being pumped into the fuel system. SO..if the engine is running fine and that is also when it is under a load and not just idling. From my experiences...for this specific thread and the problems that have been described...it is not fuel related.

I have seen that when a significant amount of water is in the fuel system...and the engine is barely running at idle. I see how the ethanol enriched fuel is now mixing with the water and now the fuel begins to look murky and not clear. And knowing that water attaches to the ethanol. IF the car is allowed to sit for a day or so...you can see a separation in the fuel tank. Now what has happened is that the ethanol and water are now one ( so-to-speak) then your fuel is now lacking the ethanol that is no longer in it due to it has separated out of it....and when the engine is cranked again..the fuel quality is now messed up and it can take a long time for it to possibly crank back up...because the fuel in the rail and injectors have separated. And the fuel at the pintle of the fuel injector is now mainly the water and ethanol blend. Which the changing can not run on that.

SO...doing a fuel line blow out and filter change is NEVER a bad idea IF fuel quality is suspect.

DUB

mixalive

Maybe so, but would it hurt anything to eliminate the fuel component? Fuel filters are a periodic maintenance item frequently neglected.

mixalive

I hope this was a customers car and not your own. 3-5 gallons of water is crazy. They must have left the fuel cap off or loose in the rain and the water got brought into the tank via gravity or vacuum from the water drain collector thingy around the spigot. And the drain from that was clogged.

corvette95

OK more info needed. To clarify when it cuts off..do you mean motor just quits running INSTANTLY and you coast to a stop or does the motor shut off and you loose all electricity to car/cabin/dash. Do you cycle the key to restart or just leave in run position and just turn it to crank again. More specifics help. We all use different terminology for same things such as no start vs no crank, lost power -means lost horsepower or lost electrical or other. Will try to help. Do you have to reset clock, radio or a/c go to 75 degrees or anything like that?

Railroadman

I'm way late to the party, stumbled across this while looking for something else. It's really not cool to post a problem here, have people try to help, then never follow up, never acknowledge the help, and never tell us what it turned out to be.

That said - my 92 went through something quite similar. Shut off with no warning. It did not refire immediately all the time, sometimes it did and sometimes I had to wait 10 minutes or longer. Sometimes it only pulled the stunt a time or two, toward the end it did it over and over, leaving me stuck on I-40 30 miles east of Amarillo in 102 degree temp!

I won't go through the whole process of elimination and diagnosis, but it turned out the sock filter had fallen off the bottom of the fuel pump, and the inlet was plugged almost solid with crud. This was causing the pump to overheat and shut off. I replaced the sock and pump, and have had no further problems in 6 years.

In the grand scheme of things it's not that difficult, not that expensive, and even if it turns out it's NOT the problem, it won't hurt to have a new pump and screen in the car anyway.