I have a Gaffrig fuel gauge in my Baja. It reads empty all the time. I checked the connections at the sending unit and I have 9.9V there and at the gauge. I disconnect the center wire from the sending unit and I still have 9.9V on the wire. I wouldn't expect this because there is no path for current to flow so I would expect 12V on the wire now. The gauge still reads 9.9V.

What's the best way to check out the gauge by itself? I want to make sure it is good before I attempt to take the sending unit out.