Hi everyone,
As of the past 3 months, I have had a terrible problem with my car running. It's been at a shop and had many things replaced on it. The list is: the ICM, Opti-spark 3 times, ECU, spark plugs, coils, and intake gasket (unrelated). When I am driving down the road, or in idle and at park, my car will suddenly shut off with no power, but the dash lights and radio stay on. It will run for around 10 to 15 mins max and once it starts warming up, then it's game over. On occasion, when I go to start it back up, it'll either keep turning over or start right back up like nothing happened. If you could help I would really appreciate it. Its a 1994 C4 auto.

 

That sounds like a fuel pump failing. At least we have had similar symptoms in other vehicles with a failing fuel pump.

 

I'll look into that, thank you. If it means anything, my battery indicator lights up on my dash cluster when my power shuts off. does that signal anything in specific?

 

Battery light should come on any time the vehicle isn't charging so I see no particular issue with that.

 

When the engine shuts off, the alternator isn't spinning.

 

Oh yeah, that makes sense.

 

First thing. Change the shop.

IF you think it is the fuel pump, try this. Put a gauge on the fuel rail and run it till it dies. See if the pressure goes down and then it dies.

 

I took the car back home lol, not Corvette reliable. I'll be doing everything else myself, but I will check my fuel pressure tomorrow.

 

I said to change the shop and not DIY, with provision. The provision being that you have the tools and the ability to DIY. Not everyone has both.

 

Since it's a 94, if you want to DIY, you could always try datalogging from it using a laptop, see if you can capture data from the car when it dies to see what exactly is dying. If you want to explore that option, here's the cable you'll want to grab: http://aldlcable.com/products/aldlobd2u.asp

And here's the software (free): http://fbodytech.com/eehack-2/download-eehack/

Very easy to use. Install, plug in the cable to the connector under the steering wheel by the accelerator pedal, then run the software and click "connect." It will automatically connect and start logging data. Then just drive around until it dies, then click 'disconnect' and click 'save' to save the log file.

Best of luck!

 

The problem and all that you have done to correct sound very familiar its all I did with same problem. There are great suggestions above but this what it boiled down too in my case.

After Opti 3 or 4 in under a year I had the car running waiting for Thermostat to open for a Top Off of Radiator and cleaning up wire looms when the car just shut off, would not start Jiggled the loom I was working on (ICM/Coil Harness cluster of wires) and it started. Inspected the them all. Found heavy corrosion and broken strands on Coil connection and broken strands on ICM plug but mostly Coil was the cause. Replaced the cluster of connections and still running 4 years later.

 

I have a garage with plenty of tools. I have a 1970 Superbee and a 1931 Chevy in the works, just haven't found the time to get the vette running.

 

Thank you for the thorough response. I can try and order that plug in and see what it's doing.

 

interesting. I'll go mess with the wires later today, just seems like so many different causes for the same exact symptoms on these models.

 

The 92-94 Opti does use a shorter connector on the harness between the opti and the car. It would probably be good to inspect that anyway. Remove the passenger side fuel rail cover, then unclip the fat 4-wire connector in the middle. It goes down the front of the engine to the opti. Disconnect it from the opti as well, then check the connectors to see if they're loose or brittle. Replacement harnesses are fairly inexpensive. Another user recently with a 94 found that their problem was a previous owner who had put a cheap poorly-made harness there and was causing the signal from the opti to drop out, making the engine unable to run.

I still believe firmly that tossing parts at the car without doing the proper diagnostic steps is poor practice, but nothing wrong with taking a look at what you have to rule it out.

 

I suppose you're right about throwing parts at it. The shop would tell me one thing and then give me another reason to why it's not running or needs another part. I guess the shop was going to keep replacing parts till they got the right one by chance. Anyhow, ill check thay today and update the thread.

 

Hello there Mason8383 and Welcome to the Corvette Forum!

You have been given some great starting points by the above posters, One thing you might want to check is the fuel lines on the Corvette. I have a 1988 C4 coupe and it sat for about 18 months. When I restarted it the fuel pressure was okay but there was insufficient flow to keep the engine running. With Ethanol in your gasoline actually absorbs moisture and this will cause rust inside the fuel lines. I measure the flow at the fuel filter inlet using a measuring how much fuel came out at 15 seconds and work from there.

Having a good scanner or even older stuff like my Snap On MT2500 would really help you at a time like this. If you are going to keep the Corvette you might consider getting on that works on your particular year.

I would start at the front of the trouble shooting section and work my way forward on you electrical system. If you don't have a set of the Factory Service Manuals you might never get this Corvette on the road where they belong.

Issues where an engine runs for a few minutes could be associated with fuel of course but also verify that your Coolant Temperature Sensor is accurate. On the L98's it really affects the fueling and that makes it an important sensor. If the sensor is telling the ECM that it is 250* at startup will give you reduced fuel as it thinks the engine is HOT. If the sensor fails cold like 0* it will activate the cold start which acts like a choke on an older car. This car would have rich black exhaust all the time and could plug up the catalytic converter if left unattended.

Last but not least, How old is your Oxygen Sensor? Your Corvette will start and run using stored data during warm up. Once the Corvette starts the O2 starts getting warmed up to work, Your year would have a heated O2 which are supposed to last a long time. Once the engine comes out of Open Loop and switches to Closed Loop it is using the O2 for data to help get accurate fueling. If you had a way to watch the O2 it would be great and helpful. The signal they produce is between .1 and .9 Volts DC. The signal should switch back and forth Very quickly from High to low. As the O2's age they tend to get a narrower signal (.3-.7) which affects the fuel calculations.
I have received a lot of poop on this site for suggesting that someone replace their O2 if it is 2 Years old (Unheated) or 4 years or 100K miles you replace the Heated O2.

You have a lot of stuff to do but your Dear Corvette will become reliable again!

 

The USB cable and software I posted earlier in the thread are all one needs for a 94-95 Corvette. This is significantly cheaper than the MT2500 and significantly more feature-rich than one. And yes, the software I posted logs the O2 sensor readings (all three!) as part of its datalog.

There are tons of differences between the '94 LT1 and an '88 (or a C3 for that matter), but in general, decent advice. As always, better to properly diagnose the problem than to just randomly throw parts at the car without any data to prove that those parts are actually bad.

 

Death Trap?

 

That is true, and I will order that code reader. However. I did short pin 4 and 12 and found my code reads on the gauge panel which goes as follows:
Module 1:
C12
Module 9:
H64
H72
H73
Module A:
C51
C52
H24
H42
H51
H52
H61
H62
H71
H76
If anyone can help point me in the right direction about these I'd appreciate it. I can go down the list to figure them out, but if anyone has some knowledge on this it wouldn't hurt while I'm doing it.