C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1995 Corvette LT1 no start

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Old Mar 5, 2019 | 09:17 PM
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Default 1995 Corvette LT1 no start

Took my car to the car wash - no, I didn't wash the engine - and it started right up. Drove it to the vacuums. Dried the car, cleaned it inside, and no start. It turns over fine, and acted like it wanted to start. Had the car hauled home from there, and let it sit a few days. Today, I hooked the fuel pressure gauge up to it, and got 44 pounds of pressure, but still no start. No "security" or "check engine" lights; just the normal lights that are present during start-up.

The car is an LT1 automatic with 161K miles on it, on an unmodified LT1 engine. Stock exhaust and all. Ideas?
Thanks!
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Old Mar 5, 2019 | 09:33 PM
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Check for spark.
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Old Mar 5, 2019 | 09:43 PM
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That's next on the list. Don't know why it would simply quit like that, though. It's 38* in my shop, it'll wait til tomorrow! LOL.
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Old Mar 6, 2019 | 07:32 AM
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DIY car wash or automatic car wash...some of those automatic ones will spray under the car causing the opti to get wet.
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Old Mar 6, 2019 | 09:19 AM
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Originally Posted by Patrick_66
.... Don't know why it would simply quit like that, though.....
Optis can quit any time
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Old Mar 6, 2019 | 10:02 AM
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Originally Posted by Patrick_66
That's next on the list. Don't know why it would simply quit like that, though. It's 38* in my shop, it'll wait til tomorrow! LOL.
Fuel pressure is good so next is spark. Optispark's can quit right out but more often I've seen them give up some warning signs first, usually a miss at idle and part throttle. ICM on the other hand, when it goes, it's done, no spark at all. I think you can lookup ICM and coil test or have them tested.
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Old Mar 6, 2019 | 12:38 PM
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Originally Posted by pacoW
I think you can lookup ICM and coil test or have them tested.
Most part stores have a tester for them.
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Old Apr 4, 2019 | 12:11 AM
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Well, I had it running for about 39 miles today...then it died. Again.

I replaced the ICM, which was 30 kinds of dead. I also replaced all eight spark plugs; because in trying to start it previously, the plugs were soaked in fuel. The coil sparks all day long, and the Optispark is fine. The car started right up and idled fine. Took it out and drove it from stop-n-go traffic to 75 mph highway speeds. Got off the exit ramp and the car started dieseling really bad as I was coming to a stop. I had enough momentum to get the car to the shoulder. It started again, but only ran for about three seconds, all that time, dieseling heavily before it quit. NO warning lights or other indicators came on while all this was happening!

So, now I'm back to square one.
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Old Apr 4, 2019 | 07:29 AM
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How do you know "the optispark is fine"?
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Old Apr 4, 2019 | 09:45 AM
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Originally Posted by Patrick_66
Well, I had it running for about 39 miles today...then it died. Again.

I replaced the ICM, which was 30 kinds of dead. I also replaced all eight spark plugs; because in trying to start it previously, the plugs were soaked in fuel. The coil sparks all day long, and the Optispark is fine. The car started right up and idled fine. Took it out and drove it from stop-n-go traffic to 75 mph highway speeds. Got off the exit ramp and the car started dieseling really bad as I was coming to a stop. I had enough momentum to get the car to the shoulder. It started again, but only ran for about three seconds, all that time, dieseling heavily before it quit. NO warning lights or other indicators came on while all this was happening!

So, now I'm back to square one.
So process of elimination here, start simple. New ICM, you said the old one was dead. These things can get real hot and need that thermal grease underneath, did you do that? Did the coil test good or are we just assuming by looking at a plug attached that showed spark? In general once you're sure coil and ICM are good, wires & plugs are good, ignition issues usually wind up with the opti. The only other thing I might check out would be the cats, potentially being plugged.
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