GMC 2004 Yokon Denali Owner's Manual page 325

The cap will hang on the hook during refueling.
CAUTION:
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If a fire starts while you are refueling, do not
remove the nozzle. Shut off the flow of fuel by
shutting off the pump or by notifying the
station attendant. Leave the area immediately.
Be careful not to spill fuel. Do not top off or overfill your
tank and wait a few seconds after you have finished
pumping before you remove the nozzle. Clean any
spilled fuel from painted surfaces as soon as possible.
See Cleaning the Outside of Your Vehicle on page 5-97.
When you put the fuel cap back on, turn it to the right
(clockwise) until you hear a clicking sound. It will
require more effort to turn the fuel cap on the last turn
as you tighten it. Make sure you fully install the cap.
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 3-42.
Notice: If you need a new fuel cap, be sure to get
the right type. Your dealer can get one for you.
If you get the wrong type, it may not fit properly.
This may cause your malfunction indicator lamp to
light and may damage your fuel tank and emissions
system. See Malfunction Indicator Lamp on
page 3-42.
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