1998 GMC Savana Van Owner's Manual - Page 247

When you put the capback on, turn itto the right (clockwise) until you hear a clickingsound. Make sure you fully install thecap. The diagnosticsystem been can determine if the fuel cap has left off or improperly installed. This would allow fuel to evaporate into the atmosphere. See "Malfunction Indicator Lamp" in the Index. Filling a Portable Fuel Container I Never fill a portable fuel container while it is in your vehicle. Static electricity discharge from the container can ignite the gasoline vapor.You can be badlyburned andyour vehicle damaged if this occurs. To help avoidinjury to you and others: 0 Dispense gasoline onlyinto approved containers. 0 Do not fill a container while it is inside a vehicle, in a vehicle's trunk, pickup bed or on any surface other thanthe ground. 0 Bring the fill nozzlein contact with the inside of the fill opening before operating the nozzle. Contact should bemaintained until the filling is complete. 0 Don't smoke while pumping gasoline. NOTICE: I you need a new cap, be sure to get the right f type. Your dealer can get onefor you. I you get f the wrong type,it may not fit properly. This may cause your malfunction indicator lamp to light and your fuel tank andemissions system may be damaged. See "Malfunction Indicator Lamp" in the Index. 6-7