What year is your truck? My brother was having a problem like this with his '01

 

its a 97

 

I have a 2001 Silverodo and it does the same thing when the truck is sitting still the guage shows empty and fuel low light comes on. As soon as you move the truck it will bounce back to the correct amount.

 

I recently purchased a 2000 Silverado 5.3L and after filling it up, the "Low Fuel" light came on and the gauge did not move up to the full mark. I too would like to know what the problem is.

 

could be fuel sender in tank or put in chevron fuel additive

 

just curious, what does the fuel additive do for the guage? I would venture a guess that the fuel level sensor is bad. Seen it a ton of times. Not sure if you still can, but when I was a wrench you could get the fuel level sensors for these without buying the whole fuel pump module. I've also seen a few that the hose from the pump up to the mudule housing was too long and would interfere with the travel of the float arm. Good luck.

 

it is to clean the sender so it reads. over time the the fuel sender get dirty and fucturate so the fuel adative clean it up

 

I guess that makes sense, but i've never seen one that was just dirty. The fuel level sensor has some tiny little spring fingers on it that touch different contacts on the sensor, and these little spring fingers wear through, causing the guage to fluctuate and read full when it's not.

 

my friend has a 2000 z71 and when he bought the vehicle he had the same problem. it is the fuel float, he had his replaced and hasnt had a problem ever since. the fuel float is inside the gas tank and raises or lowers depending on the level of fuel, thus the name fuel float, that is what tells th sensors how much gas is in the tank, the problem you all are all experiencing is that your fuel float is occasionally getting stuck either up or down. thats why it either reads full or empty when this problem happens, i dont think it is terribly expensive to have replaced but its defidently a common problem