1998 GMC Envoy Owner's Manual - Page 254

When you put the cap back on, turnto the right it (clockwise) untilyou hear a clicking sound. Make sure you fully install the cap. diagnostic system The can determineif the fuel cap has been left or off improperly installed. This would allow fuel to evaporate into the atmosphere. See "Malfunction Indicator Lamp"in theIndex. Filling a Portable Fuel Container NOTICE: If you need a new cap, be sure toget the right type. Your dealer canget onefor you. If you get the wrong type, it may not fitproperly. This may to cause your malfunction indicator lamp light and your fuel tank andemissions systemmay be damaged. See "Malfunction Indicator Lamp"in the Index. Never fill a portablefuel container while it is in your vehicle. Static electricity discharge from the container canignite the gasoline vapor.You can be badly burned and your vehicle damaged if this occurs. To help avoid injury toyou and others: Dispense gasoline only into approved containers. Do not fill a container while it is inside a vehicle, in avehicle's trunk, pickup bed or on any surface other than the ground. Bring the fill nozzle in contact with the inside of the fill opening before operating the nozzle. Contact should be maintained until thefilling is complete. Don't smoke while pumping gasoline. 6-7