1997 Chevrolet Astro Owner's Manual - Page 263

When you put the capback on, turn it to the right (clockwise) until you hear a clicking sound.Make sure you fully install the cap. diagnostic system can The 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" in the Index. Checking Things Under the Hoc4 m Things that burncan get on hot engine parts and start a fire. These includeliquids like gasoline, oil, coolant,brake fluid, windshield washer and other fluids, and plastic or rubber. You or others could beburned. Be careful not to drop orspill things that will burn onto a hot engine. NOTICE: If you need a new cap, be sure to get the right type. Your dealer can get onefor you. If you get the wrong type,it may not fit properly. This may cause your malfunction indicator lamp tolight and your fuel tank and emissions system may be damaged. See "Malfunction Indicator Lamp" in the Index. 6-7