Fuel Sending Unit
 

By looking around, it seems that I have a common problem. But before sending into the shop, want to make sure. Purchased this 2005, 2500HD, 6.0 engine. When I picked the truck up gauge said 1/4 tank. Thought I would throw in more gas 10 gal, gauge went up to 1/2. Truck sat for 2 days went to start it and gauge said empty. Thought maybe the angle of driveway was the culprit put in another 10 gal no change. So today why not fill the tank put in 6 gals which topped the tank off. Gauge then started moving all the way to 3/4 full. So am I experiencing the same problem that others have had and looking at replacing the unit. Or could this be electrical and will it show up in a form of a code?? Thanks

It'll probably show up as a code in ECM. More than likely fuel level sender. I'd just replace that unless you'd rather have a brand new pump too. I think sensor is $30 and fuel pump is $400+ through GM parts.

Thanks Sounds like a winner to me. Truck has 60k miles so I am assuming the pump should still have some life