2004 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 400

While refueling, hang the fuel cap by the tether using the hook located on the inside of the filler door. {CAUTION: If you spill fuel and then something ignites it, you could be badly burned. Fuel can spray out on you if you open the fuel cap too quickly. This spray can happen if your tank is nearly full, and is more likely in hot weather. Open the fuel cap slowly and wait for any "hiss" noise to stop. Then unscrew the cap all the way. Be careful not to spill fuel. Don't top off or overfill your tank and wait a few seconds after you've 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 5-116. 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 3-49. To remove the fuel cap, turn it slowly to the left (counterclockwise). It will require more effort to turn the fuel cap on the last turn as you loosen it. 5-8