2003 GMC Sonoma Owner's Manual - Page 271

If you get fuel on yourself and then something ignites it, you could be badly burned. Fuel can spray out on youif you open the fuel cap too quickly. This spray can happenif your tank is nearly full, and is more likely in hotweather. Open the fuel cap slowly and wait for any "hiss" noise to stop.Then unscrew the cap all the way. While refueling, hang the cap by the tether from the hook on the fuel filler door. To remove the fuel cap, turn it slowly to the left (counterclockwise). 5-8