2003 GMC Sierra 1500 Pickup Owner's Manual - Page 384

Filling a Portable Fuel ContainI . r Never fill a portable fuel container while is in it your vehicle. Static electricity discharge from the container can ignite the gasoline vapor. You can be badly burned and your vehicle damaged if this occurs. To help avoid injury to you and others: Dispense gasoline only into approved containers. * Do not fill a container while it is inside a vehicle, in a vehicle's trunk, pickup bed or on any surface other than the ground. CAUTION: (Continued) Bring the fill nozzle in contact with the inside sf the fill opening before operating the nozzle. Contact should be maintained until the filling is complete. Don't smoke while pumping gasoline. 5-9