l was driving and it overheated and eveything shutdown and now wont start l changed wires cap and checked timing belt all it does is crank but no start?
it has spark and it is getting fuel but no start

check to see if your getting gas to the fuel rail then check to see if you got fire at the plugs. no fuel, change the gas filter. no spark, it might be the module or coil.

Check your battery voltage. See how much it drops when it cranks. If it is getting fuel and sparking, l am not certain why it shut off on you. An intermittent fault like that is probably bad grounds on your spark or fuel pump circuits. It might be faulty injectors or injector circuit grounds too.

If u have a 4.3 liter Blazer they r known for fuel pump failure. When u turn the key ahead u should here the electric motor of the fuel pump “buzzing” in the gas tank. Try spraying a shot of starter fluid into the throttle body, & then starting it. You need about 54 psi of fuel pressure to start the engin. Even a drop of a few pounds & it won’t start. If ur fuel pump is failing when you’re cranking the engin the starter is drawing power from the fuel pump causing a drop in pressure.

Fuel, spark and compression is all you need to fire an engine. How hot did it get? If you drove it till it quit, then you could have cooked the head gaskets. Better find a shop.