I have a 95 LT1 :cool: So the water pump is buddy buddy with the engine in this years model. I bought this vehicle with 62K original miles in august of this year. The body in mint condition, previously owned by an Army guy who traveled alot so he didn't drive it much. Anyways, around early March I pulled up to a stop light and when the light turned green the it began to miss instantly, without any previous warning. I was able to get it to the Mechanic a few hour later and after taking a look under it he could tell that the water pump had been leaking a bit. The next day I got a call from the mechanic explaining to me that the water pump was leaking into distributor... This turned out to be a $1400 problem. He fixed this in 3 days. The car ran great for about a month until one week ago, the car began to stall out randomly once it hit about 200 degrees. I brought it back to the mechanic and he said to me "Needle in a hay stack", and I was F'n thrilled. So he replaces the ECM, and it makes no difference, this costed me $475 with labor. I take the car back to him, he takes another look at it and says, "Maybe it's the fuel pump?".

Before I go further, here are the symptoms:
1. No missing or power loss at anytime until it hits around 200 degrees, in which case the engine shuts off, with everything electrical still working.
2. Once it shuts off, it won't start until it cools to a certain point.
3. Once it cools it'll run once again until it hits around 200 degree mark.
4. Sometimes it takes up to 2 hours to cool, and between the 2 hours if you try to start it all you hear is clicking.
5. The check gauges light does cut on once it stalls.

I was angry that the ECM didn't fix it, even after he hooked it up to the computer and error code pointed to it. Now he says there is no error code. Yesterday I pushed him into replacing all the parts and wiring he did originally for the $1400 job, including the water pump. I Should get it back tomorrow to see if that did it.

Has anyone else encountered this issue? Or have any idea what would cause it?

Thanks for all your help!

...and sorry if I explained way to much.

sounds like ign. module in dist ,should be pretty inexpensive to replace.you could do it your self, when they go bad it usually does exactally what yours is doing

im a auto tec and Water Pump Leaking Into Distributor is commen i would have replaced the whole distributor and water pump some people cheat by putting a cap and rotor on. it only takes less than a hour to do the job in real time not labor guide time

I'm trying to remember without actually looking at my car, but I think there is a coolant temp sensor in the water pump. If he replaced the water pump he may have damaged that sensor or got a bad sensor. I would start by testing that first and replacing if needed. When the water pump leaks it drips on the optispark distributor which will cause it to go bad. You can get a complete Opti for around $200-275 and a water pump should be $150 at the worst. It's time consuming taking everything off that gets in the way to replace it. It doesn't make sense why the engine would shut off at 200 degrees unless something protective is going on like the fuel pump being shut off by the computer.

Thanks guys! That helped a ton, I'll check everything that was posted.

Thanks for the advice!

I have a 95 LT1 on my Impala SS and when it was still under warrantee it developed a coolant leak at the water pump and she missed and backfired just like you described. So Mr. Goodwrench fixed the leak and I never had a problem since and it now has 155,000 mi on it.

Had the same problem with my 96 SS Camaro I went ahead and replaced the whole distributor and Water pump with new GM parts and it has been OK since. You can also check with the guys on the fourth Gen site they know alot about the LT1s and it's problems