Gas gauge is crazy

[KnoxVegas]

About 3 months ago, I realized that my gas gauge was always on FULL. If I shift into neutral, the gauge hops all over the place but never really settles downs anywhere. Any ideas?

 

Model is a 1999 1/2 GMC Sierra 1500... anyone else have this problem, and if so, any way to fix it w/o going to the d@mn dealership? The truck is not under warranty anymore.

[c5vetteman]

It is the fuel sending unit. This was brought up not to long ago.

 

www.gm-trucks.com/forums/index.php?showtopic=29184&hl=fuel+sending+unit

[robsawatsky]

Yeh, my gauge reads full when full, shows reasonable accuracy to about 3/4 tank, then sits between 1/2 and 3/4 till it the tank gets close to empty. Then, it swings all the way to full and then after a while back all the way to empty and continues back and forth like that for maybe another 20 miles, then the engine stops. I've learned to use my trip odometer.

 

The reason it will bounce around in neutral or park is because when the vehicle is in gear GM enables a buffer circuit to get the gauge needle for moving around too much due to vehicle motion.