Anyone have any issues with a fuel gauge on a D-90 that does not read the correct level in the tank. Shows half full when empty. Is it a sending unit?

Bad ground? Seems to be common on Series trucks, maybe same thing on Defenders.

Might be a chafed wire. I think these gauges work by sending voltage to the tank sender (which varies the resistance) and measuring the resulting current in the wire. zero resistance (max current) is a full tank.

So pulling the tank wire off should send the gauge to well below empty if the gauge is any good. Earthing the same wire should send the gauge to the top.

Bad sender.

Mine was like that though not quite as bad, I never really fixed it, I just went based on miles. 156 to be exact.