One quick way to test the fuel sending unit with out droping the tank is to disconnect the connector inside the trunk just below the lock. One wire goes to the licene plate light and the other is the positive line for the fuel sender. If you ground the line going back to the gauge cluster you shold see it go to E. You can also measure resistance to ground through the wire back to the fuel sending unit as well. It might be best to use the actual ground wire that should be screw down to the gas tank bracket behind the gas tank under the car.

You can do both tests and in a few minutes and know weather or not your fuel gauge/fuel sending unit are working.