This is my first vehicle, its a GMC Sierra 1500 extended cab with a 5.3L in it. :) Well anyway i had to take it in to the shop to have it inspected and to go ahead and put new brakes on it since i don't have the time to do it myself. Well i asked the mechanic about my fuel gauge which hasn't been acurate for over a year now, it flips between full and empty and everything in between for no reason. Well the mechanic told me that it meant that my fuel pump will go out soon, then i told him it had been doing it for over a year, and he didn't have a response. He said that the fuel gauge is in a canister inside the tank along with the pump and some other componets. He said that it would be smarter to just replace the canister and that it would cost about 500 dollars. What do you guys think about this. Thanks for the help.

The pump is attached to the gauge sending unit inside the tank. The pump may be operating ok (for now..) but the fuel gauge sending unit and pump are usually replaced as a unit. If you do have the option of replacing just the sending unit (usually they only come as an assembly) I would still replace the pump while the tank was out of the truck.

He's correct about it being the sending unit which is attached to the fuel pump and sold as a single unit at your local parts store (about $250 if I remember correctly). There are multiple posts on this board about this exact problem with the gauge jumping around. Mine did the same thing. Supposedly you can order just the sending unit but I went ahead and replaced it as a unit just because it was easy that way and I figured I might as well replace the pump also so I dont have to do it again later. If you have about 3 hours, basic hand tools and a buddy or to or an engine hoist to help remove the bed, it's an easy job. Otherwise, $500 sounds reaonable for a shop to do it.

Also, I dont know what year your truck is but mine is an '01 silverado 1500.