fuel light stays on, on empty, when it isn't empty.

It is most likely the fuel level sending unit, but worth checking it before tearing into things.

The fuel level is measured by the PCM, and relayed to the dash over the CAN. So if you are only losing the fuel level gauge intermittently is is most likely not the dash.

To check the circuit, disconnect C1, C2 & C3 (the three 32 pin terminal connectors of the PCM). The PCM is located on the firewall on the passenger side of the engine compartment. Connect a ohm meter to Pin C3-26 Fuel level sensor return Dark Blue/White and C1-4 Sensor Ground Black/light Blue. The circuit should have continuity.

The fuel tank does not have to be dropped to change the sending unit/fuel pump assembly, instead lift the bed.

To lift /tilt the bed

* Disconnect the fuel filler neck form the bed (4 screws around the filler neck/gas cap).

• Remove the ground strap (forward passenger side of the bed) from the frame or bed.
• Remove all but the rear two mounting bolts that hold the bed to the frame.
• Loosen the rear two mounting bolts half way (closest to the bumper).
• Use a jack to lift the front half of the bed (jack and long bit of wood).
• Lift the bed until you have sufficient clearance to access the top of the fuel tank.
• Use a jack stand or suitable block of wood between the bed and the frame to keep the tank raised (don’t want to lose your head if it comes down while you are under it).
• Clean the area around the fuel pump/sending unit before disconnecting any of the fuel lines or removing the unit from the tank.
• Disconnect electrical connector and fuel lines.
• Take note how the fuel pump assembly is clocked, the new one must be installed the same.

Take your time and remember to not use a flame near the fuel.