Theoretically, you could take the pump apart and replace the check valve pieces, provided you could find a way to buy them. Otherwise, you just replace the pump.

You can check fuel rail pressure before you go attempting to start the truck. If you've got no pressure in the rail, something has leaked it out.

You've got three different things that hold the pressure in the fuel rail. The check valve in the pump, the pressure regulator at the other end, and the fuel injectors themselves. If any of those three leak, you will lose pressure in the rail and have a longer cranking time getting the truck to start.