Chevrolet TrailBlazer 2007 Owner's Manual page 388

CAUTION:
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If you spill fuel and then something
ignites it, you could be badly burned.
Fuel can spray out on you if you open
the fuel cap too quickly. This spray can
happen if your tank is nearly full, and is
more likely in hot weather. Open the fuel
cap slowly and wait for any hiss noise to
stop. Then unscrew the cap all the way.
388
Be careful not to spill fuel. Do not top off or overfill
the tank and wait a few seconds after you have
finished pumping before removing the nozzle.
Clean fuel from painted surfaces as soon
as possible. See Washing Your Vehicle on
page 493.
When replacing the fuel cap, turn it clockwise
until it clicks. Make sure the cap is fully installed.
The diagnostic system can determine if the
fuel cap has been left off or improperly installed.
This would allow fuel to evaporate into the
atmosphere. See Malfunction Indicator Lamp
on page 208.