How do I access the sending unit? Diagram would be helpful.

Do you mean the fuel level sending unit? If so, open the tonneau/top storage compartment, on the left (passenger side) you should find a 4" round 'patch' of material in the bottom of the compartment. Peel this piece and place out of the way; disconnect wire lead; place rags or newspaper around the fitting; unscrew fitting and remove sending unit and seal; either replace with a new unit and seal, or you can try cleaning the sliding mechanism and replace the existing unit.