Re: Fuel guage won't drop below 1/2
1) Does the gauge go to "E" with the key off? (Yes or No)
2) If you know roughly how much fuel is in the tank, disconnect the wire (normally pink) from the center terminal of the fuel sender in the tank (or at the "S" terminal on the gauge).
3) Measure the resistance between the sender and ground. If you disconnected the wire at the gauge measure between the wire and ground. If you disconnected the wire at the sender, measure between the SENDER and ground.
4) A full tank of fuel should measure 33 ohms, 1/2 tank = 109 ohms, and empty = 240 ohms.
Therefore, if you have more than 1/2 tank of fuel the readings should be somewhere between 33d and 109 ohms. Any less than 1/2 tank would still read roughly 109 "IF" the sender arm was stuck or there was a sender issue that prevented the arm from lowering more than 1/2 tank.
DO NOT replace the gauge as gauges are rarely the problem. If this test is inconclusive, pull the sender and check it manually.