I have convert my 1975 Truck from a 1991 Firebird GTA 5.7/TH700. After my convertion the truck ran fine for a year then I start having problems. The truck start and run fine while its cold...as soon the get hot or when the electric fan start running for about 5-15 mins the engine start shaking anf the idle goes up and down untill the engine dies and wont start after that until the cools of...

What I've done so far:
I've checked the IAC and replaced it, I did a minimum air, and adjusted the TPS.
Checked fuel presure 42psi key on and 39psi engine running.
Base timing is set to 6 degree.
No Error codes.

Could it the engine is over heating then shutdown???

Thanks

 

i had the same problem, but with a 1992 cavalier Z24. i replaced the knock sensor and the knock sensor plug and it solved the problem.

 

does the volts gauge go wacky as well

 

I had a similiar problem with my '89, although I never did figure it out I suspected it was the ignition module overheating. I have a theory but never tested it.
Get some of that silicone grease they use and smear a goodly amount under the module
it will help absorb some of the heat.

 

it's probably either the knock sensor or the plug, cuz if they're defective and heat up too much then it reads as your engine being too hot and so it will shut off only starting when it's cold again. it's just the knock sensor or the plug that connects to it.