1999 GMC Sierra 1500 Pickup Owner's Manual - Page 310

Service & Appearance Care I IC\ Operatingtheenginewiththeaircleaner off cancauseyouorothers it stopsflame to beburned.Theaircleanernotonlycleanstheair, if theenginebackfires. If itisn'tthere,andtheenginebackfires,you couldbeburned.Don'tdrivewith it off, andbecarefulworkingon off. theenginewiththeaircleaner If the air cleaner is off, a backfire can cause a damaging engine fire. And, it. Alway! 3 tl dirt can get your easily into engine, will le which dan air cleaner in place when you're driving. To remove the air cleaner filter on a gas engine, turn the wing nuts counterclockwise.Removethecoverandchangethefilter. fi 3 Fnning 1 6.5L Engine K2151 Ona6.2Ldieselenginetherearetwowingnuts.Ona6.5Ldieselengine, unhooktheclips. 6-32