Topic: What would keep the fuel sending unit from working?

[Matt1968]

It works fine outside of the tank (lead hooked up, a ground wire attached from sender to tank opening). Gauge works the full range.

Installed with 5 gallons of gas poured in (16 gal tank) it reads fully empty. Float is currently in a pot of water, not sinking.

What's going one?

[67gta289]

Bad ground sending unit to tank and/or tank to body and/or body to battery

[midlife]

Another possibility is a broken wire for the fuel sending unit (yellow/white).  Yet another possibility is that the gauge itself is mis-positioned on the dash cluster, causing it to be grounded.  When that happens, other gauges (water temperature, oil pressure) are also off.