I have the same problem with my new sending unit,(from L.M.C.)When I first installed it,no problems. then I installed a new wiring harness. Turned on the key-FULL. I had less than 1/2 a tank. I checked the continuity at the gauge itself. Gauge is fine. I checked my ground connection at the sender,and that,too checked out fine. The problem is with the sending unit.It won't register with everything connected,)KEY ON),and moving the float! Even though they are new,doesn't mean they work O.K. Even though I have less than 1,000 miles on the truck since i bought it,there's no warranty,since I bought it 3 years ago. I'll just have to buy another one,and HOPE!!
