If your fuel gauge is giving you wacky readings, it is more than likely the fuel sender (#110555). But how do you know for sure? Here is a way to test the fuel gauge to make sure it is not the culprit (courtesy Dave S at DMC Midwest):

§ Open the trunk and remove the carpet and Trunk Inspection Cover #105168.
§ Locate the fuel sender. There are three connectors on top of the fuel sender. Start with the plastic connector plugged in.
Test 1:
a. Jumper the connectors on top of the fuel sender that correspond to the green wire w/black stripe and the black ground.
b. Turn on the ignition.
c. The fuel gauge should read empty.
Test 2:
a. Remove the jumper and disconnect the plug.
b. The fuel gauge should read full.
Test 3:
a. Plug the plastic connector back in.
b. Jumper the connectors on top of the fuel sender that correspond to the light green wire w/orange stripe and the black ground.
c. The low fuel light should turn on.

If any of the three tests gave you an unexpected result, you may have a problem related to the fuel gauge or wiring etc. However, if all tests “passed”, your fuel gauge is good and the problem is most likely the fuel sender.