Been awhile since I've been on the forum and sure enough an issue with the vette has brought me back here!

1994 Corvette LT1 Automatic

Car was running fine on the highway and it suddenly shut off. 'Check gauges' came on and nothing more. Wouldn't start so I had to get it towed back to work.

Did a diagnostic check and no codes came up.

Due to my work schedule, diagnosing my car consists of taking time while I'm at work to do anything..wearing suit and tie.

Tested for fuel; I had a near-instant loss of fuel pressure during key-on-engine-off immediately after the fuel pump had primed. Replaced the fuel pressure regulator and now during key-on-engine-off, my fuel pressure remains at 40psi.

Car cranks, but still doesn't turn on. Weird because I thought my bad FPR caused my car to die on the freeway.

When I have a chance I will try to test for spark tomorrow (during work again).

My question is;

Is the best way to test for spark on this at the coil off a plug? Or is there a way to check for spark at/by the ICM?

If I DO have spark, whats the next course of action on an LT1?

If no spark, I'm assuming I should pull off the ICM and get it tested or replace it right away?

*Side note* it'd be weird if I didn't have spark suddenly because if a no spark issue caused my car to die..then why did I have no fuel pressure after the fuel pump primed?

I'm sorry if these questions have been asked many times. I have done searches but I've come up with tons of weird things. Oh and no I didn't have a security light on so we can rule out the VATS system. I'm just trying to minimize my time under the hood while at work and well, I've been working these past 8 days now straight so haven't had any time off.

 

Oh and one more thing, during cranking my fuel pressure remained consistent. It did not drop while I cranked it.

 

I knew a guy who had the exact same symptoms. He spent a lot of time and money troubleshooting and replacing parts until he determined that…

there was no fuel in the tank.

"Check gages" -- did you do that?

 

"Doh"!

Assuming that there is fuel in the car, my bet is the ICM. Just take a spark tester and see if you have spark coming from the coil. If not, have the ICM checked. If you do, check to make sure that spark is going into the opti by checking the spark at the opti connection. If no spark, replace the coil wire, yes, it can split, crack, arch, etc. If you have spark going to the opti, then of course check spark at plugs, several if not all. If you have spark at plugs, then you most likely have fuel issue. Although, the PSI don't indicate that.

 

Lol I had just filled the tank with 16 gallons 2 days prior to this happening. I've driven a total of 40 miles within those days (to and from work only). I just thought I'd mention the 'check gauges' in case that was a sign of something else. Cluster also shows 3/4 of a tank full which makes sense considering the little I've driven.

 

Tested for spark by unplugging the coil from the optispark (that comes from the ICM).

No spark.

I'll dig out my FSM that I recently found and diagnose further.

Is the ignition coil difficult to remove? That's in case the ICM tests ok which I might pull off and have it tested at autozone or some parts store. I've tested the fuses that are found inside the cabin in the passenger side as well as the fuses located near the battery; all tested OK.

Edit: I tested for spark using a test light (one end grounded) and the other end at the end of the coil. Didn't see a blue arc nor did the light in the test light come on. Not sure if that was the proper way.

 

Replaced the ICM, all is fixed!

 

Glad to hear you fixed it and posted a result!!!

 

Good work.
Did it on your own, you don’t need the Forum.

The coil is a pain to do. You have to drill out the old rivets to use the existing mount. Then install long screws to hold it in. ICM much faster to replace.

Coils don’t go bad hardly ever. ICM much more common.