1997 Chevy Blazer LT Gas Gauge Problem

I recently bought a 1997 blazer LT great truck 136,000 it appears run great some major parts appear to recently been replaced. My problem is the gas gauge dosen't work it's all over the place even when the tank is full and I can't tell how much gas is left. Can some one help with some advice or maybe tell me what the problem is?

To me, it sounds like a malfunctioning sending unit. They sometimes go all sorts of nuts on these trucks. Mine indicates 1/4 tank more fuel than it really has. Your choices are to live with it, and schedule a trip to the gas station based on your odometer reading (about 250 miles, tank up) - or spend the bucks if you are not sure of your skills. It will have to be replaced. This is minor surgery:

Tanks has to be drained.
Tank has to be dropped.
Entire sending unit has to come out and replaced.

The storing and handling of fuel is not to be taken lightly, you will have up to 20 gallons of the stuff around if you have to drain a nearly full tank. While you are in there, weigh the possibility of spending more bucks and getting the filter screen and the fuel pump replaced. Take care of it in one shot, and it will go at least another 130k Miles before there is reason to think twice about it. :)

Yip, replace the sending unit and as wolfox said, you might as well drop a new pump and strainer as well in there.

Mine just blew at 135,000miles.

Thanks guys I appreciate it... I suspected it would be expensive to repair.