I got a 1999 Silverado 1500 5.3L Z71 and when ever i fill my truck the first 50 or so miles i put on it the gas guage wants to go back and forth for empty and full and sometimes makes pitstops in the middle. But after the 50 or so miles it will usually never do it again until i put fuel in it again. Does anyone know what is wrong with it. Is it the fuel sender, fuel pump, fuel filter, or something like that. I would appreciate the help. thank you.

 

My brother in law has a 2000 silverado and it had the same problem. The sender is in the fuel pump so the whole thing had to be replaced (about $300 for the part). I have the same problem with my 2001 but I'm holding off on replacing it due to the cost since it hasn't caused any problems other than the gauge going up and down.

 

Got the same deal on my 2000. Doesn't bother me, so I'm letting it go for now.

 

its the fuel sending unit