[Will D]

Lookin for any tips or ideas before I tear into it. My fuel gauge sits at empty as expected with the key/switch off. When I turn it on, the needle rises just above half full. I drained the tank a little bit ago to change out the old fuel and with the tank bone dry the gauge needle was just below the half way mark. Would you think gauge issue or sending unit? Was going to start with checking the gauge with a D cell battery as Jseery suggested in someone else's thread. Then maybe run a temporary external wire from the gauge to the sending unit before pulling the sending unit for inspection...