Hello,I have a 1994 chevy 2500 with a 5.0 engine. The truck will not restart after it has run and warmed up.?

I have changed the fuel pump relay and the coolant temp sensor so far. I can hear the fuel pump run when the truck is cool but when warmed up at restart the pump will not run till the engine cools down to under 100 degrees. Thank you for any help with this. Rick