How do I change the fuel pump on a 1990 GMC Sierra?

To change the fuel pump on a 1990 GMC Sierra, first, disconnect the negative battery terminal and relieve fuel system pressure by removing the fuel pump fuse and starting the engine until it stalls. Next, lift the truck and support it securely, then remove the fuel tank by disconnecting the fuel lines, electrical connectors, and support straps. Once the tank is down, access the fuel pump by removing the retaining ring, replacing the old pump with the new one, and reassembling in reverse order. Finally, reconnect the battery, check for leaks, and ensure the pump is functioning correctly.