I have an 89 Firebird w/ 305 engine TBI 156,000 miles. Lately I have experianced a problem with the engine shutting down. You have to go at least 60 miles before the problem starts. You can be going 80 MPH or any other speed. The engine does not over heat. With no hesitation the engine will shut down. The check engine lights do not come on, the RPM reduces as the peed of the car decreases. After shut down, car will coast for a short distance and then start up again as if nothing is wrong. I just finished a trip about 250 miles and this happened about 15 times. In trying to fix the problem, I have replaced the EGR ,replaced the fuel filter, replaced the distributor w/modul, new cap and rotor. Talking with a couple mechanics, they are saying it could be electric or fuel. The one mech. says fuel pump pressure is good. Does anyone have suggestions ?
Ross

 

I had one that did that also. The previous owner had added all kinds of electrical stuff,and then removed them prior to sale. It turned out to be a bad computer. It was throwing all kinds of codes out causing the engine to shutdown. Just something to check.

 

Let me add to what vmax has described as I have been in the car when it did this and have been helping him in trying to find the cause. This condition has been occuring in this car for several years now. Until recently it only occurred when we were on the road for several hours, usually with our bikes on a trailer and in tow. The shutdown and following attempt to restart the car seemed to precisely duplicate a vapor lock condition. After a brief cooldown it would restart and then gradually get better again as if the boiled fuel worked its way thru and away we would go again. If it had been a carbed car I would have bet the ranch on vapor lock as the cause. There are no fuel lines that seem to be running close enough to any exhaust or other heat source to cause this however, and I am not sure it can even occur in a fuel injected car. Under normal daily driving this car runs perfectly which is what has made this problem so hard to try to track down.
Ideas anybody?