dtana

Probably more details than necessary, so I apologize, but I know from reading here how frustrating it must be when someone asking for help leaves out important details.

So I have a 93 6 speed that I bought last October. Been running great until Friday. Plenty of gas in the tank. Started up normally on the first try. Drove maybe a mile, I'm in 5th & the engine just cut out for a split second, but then recovers & car keeps running. When this happened the revs dropped to zero & the Service Engine Soon light came on for a second & then shut off. Then it cut out again maybe 10-15 seconds later. So I make a U turn & head back home. As I'm heading back I try to replicate the problem by running up & down through the gears, then had to stop for red light etc. Couldn't get the problem to repeat itself. Even drove it around the block a few times. The car ran fine, accelerated fine & I didn't notice anything else unusual.

Later that evening got back in the car & started it up. It's fine as I pull away & I make it maybe 100 feet until I have a stop sign. As I pull away from the stop sign it cuts out & dies completely. It was not because I stalled it. Cranked it & restarted, drove another 10 feet & it died again. Pulled over, tried to restart & now it just wouldn't start at all. It would crank but wouldn't actually fire up. Tried 5, 6 times, no luck. So I'm only like 200 feet away from my house & I walk back & take my other car to get to my meeting. I leave the Vette where it sat. An hour or so later I'm back & figured I'd give it one more try to see if I can at least get it back home. The car starts right up & idles normally. I put it in first, accelerate briskly, figuring that I could coast it home if it dies again, but it doesn't. Haven't touched the car since then.

Figured I'd tow it to Precision Motive tomorrow which is only 6 miles away from me.
But I don't know them & though some of you have said nice things about the shop, I'd still like to get some input as to what you guys think is going on here. I'd just feel better not being totally clueless, so any help narrowing down the possible causes would be greatly appreciated.

Retxpres

Relieve the pressure on the gas tank. Open the cap... Give it a try.

JVH

Replace the fuel pump and sock

jmgtp

On the instances where it cuts out but recovers does the tach go to 0 during the cut out? If so this doesn't sound fuel related because if it was fuel related the tach would still show actual rpm, which obviously couldn't have gone to 0 if the motor recovered. Sounds like an ignition problem. I'd start by looking at ICM and possibly Opti.

1993C4LT1

dtana

Yes, it did drop way down, but I couldn't swear it hit zero. Like, I said it happened & then was over really quickly...............no more than a second from start to finish.

jmgtp

Given that your car is a manual transmission - it is impossible for the revs to have dropped down so rapidly. Think of it this way, say you are cruising at 2000 rpm and you turned the ignition switch off. The motor would continue to be driven by the cars momentum, it's "locked" to the wheels by the diff/trans/clutch. Sure, it would start to slow down as the compression of the engine slowed the car. But it would be impossible for it to rapidly drop to near zero, unless you disengaged the clutch.

So, since you didn't shut off the ignition while driving, the tach will continue to report actual engine speed - unless it isn't getting a signal. Which seems to be the case in your car. Time to pickup an FSM and troubleshoot the ignition. Don't throw expensive parts at it on a guess. I had a bad ICM show the same symptoms you mention, though it seemed more often to happen on a hot motor (and therefore hot ICM as it's bolted to the cylinder head). Unfortunately, my bad ICM tested good at the parts store. That was a case where I did replace it on a hunch, and it worked.