Would any one know why my fuel gauge is always on full?i unhooked the plug at the tank and still goes past full.i put a new gauge in and still past full.when i turn the key off it goes to full and as soon as i turn it on it goes past full.getting sick of running out of gas on I81.i have noticed that when i am low on gas the needle does drop to full.

 

Here's a much newer thread from our Tech Article (DIY) section that will take you from start to finish on diagnosing fuel gauge/sender problems:
98+ Fuel Gauge Diagnosis

 

forgot to say its a 1996 blazer.