You need to remove the fuel tank.
REMOVAL & INSTALLATION
Properly relieve the fuel system pressure.
Drain fuel from fuel tank.
The fuel tank has reservoirs inside to maintain fuel near the pickup during vehicle cornering and under low fuel operating conditions. these reservoirs could block siphon tubes or hoses from reaching the bottom of the fuel tank.
Raise and support the vehicle safely.
Disconnect the fuel tank filler pipe and vent hoses.
Place a safety support under the fuel tank and remove the support strap bolts.
Lower the fuel tank slightly.
Label and disconnect the fuel tubes, electrical harness connectors and vacuum lines from the fuel tank.
Remove the fuel tank from the vehicle.
Position the fuel tank in the vehicle.
Connect the fuel tubes, electrical harness connectors and vacuum lines.
Raise the fuel tank into position and tighten the support strap bolts to 321-39 ft. lbs. (41-54 Nm).
Connect the fuel tank filler pipe and vent hoses. Tighten clamps to 27-35 inch lbs. (3-4 Nm).
Lower the vehicle.
Fill the tank with fuel.
Start the engine and check for leaks.
With the fuel tank it you need to remove the collar that holds the fuel pump in place, they make a special wrench to grab the plastic collar or you can use a brass punch and hammer to avoid making sparks around the fuel system. Once you remove the collar pull out the pump and replace the pump and oring under the collar on the tank otherwise you will have an evaporative emissions leak and the check engine light will come on.Coat the new oring with vaseline and the htreads on the collar and make sure the cap is installed completely.