91 Z28 5.7 suddenly stalls while driving as if you turned it off! Happens going fast or slow & cold or not! Won't start again for 15 minutes to 1 hour after it stalls - cranks strong but won't fire up! Mechanic can't duplicate the problem & runs like there is nothing wrong with it until it suddenly stalls again! Has happened several times & is becoming more frequent! Any ideas? Help!!!

 

When it won't start, you need to check to see if you are losing spark or fuel pressure (test gauge needed).

 

91 Z28, 5.7 - Car starts first in morning then after driving anytime after 5 minutes to 20 minutes it will just shut off, even when it has barely warmed up! Then it won't start again for 10 minutes to 1 hour. It keeps cranking but won't fire up! Problem is that you are always stuck on a road somewhere & have no way to test anything & when it is towed to the mechanic it always starts right up! Then nothing seems to be wrong & can't duplicate the problem until the car acts up again in a few days or a week!

 

I'm with "shoebox" you need to check fuel and spark when it acts up? I have had an Opti, ICM and fuel pump all give about those same symptoms...just acquire a fuel pressure gauge and injector noid light "pick up at most auto part stores" to check for pressure and injector pulse, spark can be easily be checked by pulling a plug wire.

Best of luck!

 

Check your coolant temperature sensor they can make cars do funny things.

 

I have had that problem. It is a dangerous problem while driving.

App... 97ss 383/D1 MM6. Usually happend when it warmed driving down the road during cruz speeds. My T_shooting pointed to the opti encoder.

Connector was OK, but, I think a loose terminal or bad solder joint in the circuirt. I could get it to start by forcing the connector (@ the opti) to engagement direction and a bit of wiggle action. Engine fired up. But then, another failure down the road.

I changed the opti. Now, no problems. I did not have any coolant leak or over temp problems. B.

 

I have a 1991 Z-28 with a 383 TPI with a 6 speed. Mine has been doing the same thing for a few years now. I replaced the distibutor, took off all aftermarket Accel Ignitions coil pack etc, went back to stock. NO CHANGE. Put a brand new gas tank and fuel pump in the car. NO CHANGE. Replaced the ECM with a Dynamic EFI EBL programable made the car run great but it still sytalls. I have a fuel pressure guage on the windshield post and it drops to zero when this happens, shoots upo to 50 lbs then about 4 seconds later back to zero pressure then back to 50 lbs and continues all over again. When I would stop for gas and turn the car off I would have to wait 15 minutes and then the car would run again. It turns over but does not get fuel. I put a noisd on the injectors when this was happening and it showed a weak signal. I replaced every ground on the car with neew ones I can't think of another thing to fix this. I'm hoping the guy whos going to put a street tune on the new EBL will be able to find out the problem the car has a TT-1 Controller which may help identify the problem. I KNOW HOW YOU FEEL!!! It's frustrating to say the least. I HAVE BEEN SCOURING WEB SITES FOR ANSWERS BUT NO HELP YET.

 

Maybe the waterpump has a small leak that is shorting out the opti.
I had that happen to me when I first bought my car.

 

Might need to go back to old school mechanics for this. Usually, not always, this is an issue with the ignition module in the distributor. Gets hot and fails, cools off and works again. And it would also lose the rpm signal to the ECM and cut off the injectors. I'd take it to a parts store and get it tested. New one is about $40. No Opti on the 91 models here.

 

I have a 96 SS that started stalling during driving and then would take a long time to restart...the last time it happend I have not been able to get the car restarted checked the wires and plugs with an ignition test and even replaced the ICM...got the car to start and run for about 2 min. the stall and no start! I have no idea what to do next.