GM Service Manual Online
For 1990-2009 cars only

The fuel sender is located inside the fuel tank and is attached to the top of the fuel tank.

The fuel sender has a float, wire float arm, and a rheostat. Fuel level is sensed by the position of the float and float arm which operate the 90 ohm rheostat. As the float position changes, the amount of current passing through the rheostat varies, thus changing the gage reading on the instrument panel.