Chevrolet 2002 TrailBlazer Owner's Manual page 157

Here are four things that some owners ask about. None
of these show a problem with your fuel gage:
D
At the gas station, the gas pump shuts off before the
gage reads full.
D
It takes a little more or less fuel to fill up than the
gage indicated. For example, the gage may have
indicated the tank was half full, but it actually took a
little more or less than half the tank's capacity to fill
the tank.
D
The gage moves a little when you turn a corner or
speed up.
D
The gage doesn't go back to empty when you turn
off the ignition.
2-88
Low Fuel Light
United States
The light next to the fuel gage will come on briefly
when you are starting the engine.
This light comes on when the fuel tank is low on fuel.
To turn it off, add fuel to the fuel tank. See "Fuel" in
the Index.
Canada