GMC Troubleshooting Questions? Ask a Mechanic for Answers
Can you hear the fuel pump run each time when you first turn the key to run, for about 10 seconds the fuel pump should run, before you turn the key to start. If sometimes the fuel pump doesn't run, you may have a problem in the fuel pump circuit. Wiggle the fuel pump relay and feel if it's loose in the socket. If not, try a new relay.
Did a new relay fix it?