gas gauge trouble
 

I have a 86 chevey silverado with a 350 and dual gas tanks. Last year it seemed like the truck would run forever on empty. Now i run out of gas with it still reading a quarter of a tank left on either tank. When i fill the gas tank fullthe needle is pointing about an inch past the full mark now.Can anyone tell me whats going on and if theres a fix for this problem ? thank you