The other day I went to grab lunch, and on the way home, I was doing about 55 mph and my motor completely shut off. I still had all power (lights, radio, etc.). I pulled over and couldn't get the car started again. It would crank and try to start, but it just wouldn't turn over.

The next day, I went out and it fired right up without any hesitation...I drove it around the block and it was fine.

Today, I started it and drove it about 2 miles and it completely died again while sitting at a stop light. Same thing...let it sit for several hours and it started right up again. Got it home, it idled for 30 seconds and died.

When I turn the key over one click, I can hear the fuel pump prime. I checked all of the fuses, etc., and I have plenty of gas. I'm going to put a fuel pressure gauge on it tomorrow.

Anyone have any ideas??

 

Vats by any chance? Any codes?

 

No codes.

Would VATS work sometimes and not work other times?

 

Your ignition switch is most likely on it's way out.

 

How would that be determined?

 

Hey man i have the same problem i am trying to figure out, I'm not saying its not whats wrong with your car but i put a new ignition switch in today and still the same problem. If you find out what it is let me know.

 

If it were your VATS going out I think it allways throws a code. Maybe its some kind of chasis ground that comes loose when it gets hot.

 

Damn dude I would say if you hear the pump priming then it's probably not fuel related, but the only way to tell would be to put a gauge on it. If it's not fuel, then it's gotta be spark or something related to/controlling spark. Odd that you're not getting any codes though. GM diagnostics ftw.

 

Could be your fuel pump how many miles are on it. Does it only happen when the vehicle has been running for awhile. When the fuel pump gets hot the windings in the motor may no longer be touching the brushes. Once the pump cools down the windings and brushes make contact for the pump to work.

Try to have a fuel pressure gauge on it when it dies.
After it shuts off can you hear the pump prime.

 

The car (and pump, etc.) have just over 100k miles.

The first time it happened, the car had been running for about 10-15 minutes. The second and third times, it happened after 1-2 minutes.

After it dies, I can still hear the pump priming. I'll try to get a gauge on it later.

 

What do you guys think about the ICM? Could it cause a problem like that?

 

It's very possible...is the coil a stock unit? MSD's are known to fail randomly...

Try replacing it and see what happens. Can't hurt and it's not very expensive.

 

The coil has been changed, but the ICM is original.

I might pick one up when I buy a fuel pressure gauge.

 

What kind of coil is in it?

 

Thats what mine sounded like I was on the interstate doing 70 and all the sudden my car engine shut off, coasted to the side of the road and waited about 10 15 min and cranked up and went on fine that day, but started doing more often. I would think it would be your Optispark replaced mine and have not had any trouble since then. Also I replaced my ICM before the opti and did not help.