Gas Gauge

Is that a one wire sending unit, if so, with the key on, that one wire should have voltage, does it? If not, the problem could be the gage--instrument cluster--wiring circuit. There is a gage fuse, but, if the other gages work, it isn't the fuse. Back in the day, I mean a long time, I'm in my 70s now. With access to the float assembly, I used a digital multimeter on the electrical terminals and did an ohms test. Worked the float up and down as I watched the readings move up and down, like it should, so I knew the sending unit/float assembly was ok. Just my opinion.