Things You'll Need
Hex bolt head
Removing and replacing a fuel pump in a 2003 Silverado 1500 truck means replacing the entire pump/sending unit module that is mounted within the fuel tank. This pump can wear out if you constantly drive your truck with the fuel level low. You need the fuel to be low, however, if you are going to replace the module. Siphon out as much fuel as possible with a proper vacuum pump kit if needed; never siphon out by mouth.
Remove the fuel pump's relay from within the engine's fuse box; look to the box's diagram for the relay's location. Crank the engine for several seconds, look for it to stall and then disconnect the truck's negative battery cable.
Open the gas cap door and unscrew the flange that surrounds the filler pipe; these screws will take a screwdriver with an inverted hex bolt head.
Raise the truck's rear end and support it on jack stands. Unbolt and remove the fuel tank's shield with a wrench and then disconnect the ground strap on the filler pipe.
Disconnect the EVAP canister lines at its quick connect fittings and then unbolt and remove the canister from its bracket using a wrench.
Disconnect the lines and electrical connectors from the fuel pump module's flange on the tank. All these connectors should use quick-connect fittings that you press either by hand or with a small screwdriver's help.
Raise a transmission jack under the fuel tank to boost it. Unbolt the support straps with your wrench, lower the jack and remove the tank.
Press and release the locking tab on the fuel pump module's flange ring using a needle-nose pointer while grasping the ring with a large pair of locking pliers. Turn the ring counterclockwise using the pliers to loosen it.
Grab hold of the pump module by the line fittings and lift the module out of the tank.
Lower the replacement fuel pump module down into the tank. You must make sure you don't damage the pump's float at the bottom, and then align the module so its line fittings point in the same direction as the old one.
Press down on the module to seat its retaining ring and turn it clockwise to engage the locking tab.
Place the fuel tank back on the jack and raise it back into position on the truck. Connect the straps with your wrench.
Reconnect the fuel lines and electrical connectors to the fuel pump flange at their quick-connect fittings. Re-install the EVAP canister within its bracket and connect its lines.
Connect the ground strap and shield back to the fuel tank and lower the Silverado off the jack stands.
Reconnect the truck's battery cable and fuel pump fuse.