gas gauge is temper mental

[the fall guy]

I have a 85 k5 siveraldo...just recently the gas gauge started to show empty when i started the truck and after a couple of smacks on the dash it started working again....just wondering if it's a bad conection or time for a new gauge?
thanks

 

[alec78]

Bad connection... not likely. A bad connection is going to give a full or 3 o'clock position on the guage.

To read empty there has to be 0 ohms (grounded).

I would lean towards a short to ground that is released when you beat on it or a bad guage.

 

[stizkidz]

Mine sucks too. When I fill the tank, the needle points to about 1/4 above full. After it reaches the 3/4 tank mark, it pretty much drops fast and I need to fill up again soon.

 

[hawk368]

I watched mine as I filled up after barely getting to the station. I have the 31 gallon tank. But my gauge read full at 23 gallons on the pump. I know I was empty when I started because it took 31.5 gallons when topped off.