1994 Corvette... LT1.

Alright, here's the rundown.

C4 has been running fine with no real issues. Took my targa top off, drove it up the Blue Ridge Parkway for an hour or so, no troubles at all. Got home, sky looked clear, thought screw it I'll put the top on later (stored outside with no roof).
Of course, mountains being mountains, a sudden rain rolls in. I run out, get the roof on, and cover it. All in all, it got about 1 to 2 minutes of rain in it. I got a few towels in there and wiped off everything as best as I could, really the only thing staying wet was the carpet.

Next day, I uncover and assess. All seems dry, besides the damp carpet which I still had towels on. Gave it a crank, car started right up. It sounded a bit odd, and after driving for about a minute in the parking lot, it started to sound normal again. Then, POP. Something made a loud pop noise under the hood (I think under the hood? Not 100% certain), and the car died. Battery light came on as it died. Since then, no start.

Gave it a jump thinking maybe the battery had issues (it was an old problematic battery), no luck. Exchanged it for a new one since the old battery had a free warranty soon to expire and was being troublesome, new battery didn't fix issue.
After some scouring some forums and talking, I ended up replacing my ICM. Seems random, but I was hopeful that was the issue. No luck, but atleast I have a new ICM and fresh thermal paste.

Checked fuel pressure at the valve, all was good. 45-50ish. Battery voltage is strong and holding. Checked every fuse, all was good.


When I try and start now, it cranks but doesn't start. Video attached. Occasionally, there's a puff where it pauses and white smoke comes out of the air intake. I'm guessing this is fuel building up and being ignited by intermittent spark, but since the engine as a whole isn't turning over it's just shooting out the open air valve. Exhaust pipes also reek of straight gas, so I'm almost certain the injectors are spraying and it's just not being lit.

So given all of this, I'm almost certain it's ignition related given the moisture exposure. It's not the moisture itself in the cabin that concerns me, more is it the fact that the whole car was wet and covered and all of that moisture built up and made it a dutch oven of moisture trapped under the cover. I know I'm going to get a bunch of OptiSpark messages, and I get that it's very likely, but I want to know what I can do to test the whole ignition line and figure out exactly where the signal is dying and failing at. I don't want to throw several hundred bucks and hours of work at a new Opti just to find it was actually this or that instead.

What are some other educated guesses into what all could have gone wrong and busted? If ignition, what's the best way to test the system? Is there some other tell from the video of what's going on? I have a spark tester and cylinder pressure tester coming in the mail soon, once I get those I plan on going cylinder by cylinder figuring out if there's spark and if it's making even pressure across the engine.

 

I am not an LT owner but do you ever drive it in the rain, water in the fuel/fuel cap is what I am thinking.

 

Interesting, hadn’t thought of that. Is there any easy way to test? And if so what’s the best way to drain it?

 

Do you have a schrader valve on the fuel rail to test fuel pressure? Pull fuel right out of the fuel rail but pull quite a bit in case it is all water. Check your fuel compartment drain hose / hole for being clogged.