1999 GMC Sierra 1500 Pickup Owner's Manual - Page 287

7 F . K2451 3. Withtheengine off, openthewaterdrainvalve 2 to 3 turns. 4. Starttheengineandallowittoidlefor isobserved. 5. Stoptheengineandclosethewaterdrainvalve. 1 to 2 minutes,oruntilclearfuel 6. Install the fueltankcap. If the WATER IN FUEL lightcomesonagainafterdriving a shortdistanceor theenginerunsroughorstalls-alargeamount ofwaterhasprobablybeen pumpedintothefueltank.Thefueltankshouldbepurged. ~ CAUTION A Dieselfuelcontainingwater is still flammable.You If youeve:r try todrainwaterfromyourfuel,kee,p . smoking materials away from the mixture. could h~ burmi. sparks m e s d . I If there is water in your diesel fuel and the weather is warm or humid, fungusandbacteriacangrow in thefuel.Theycandamageyourfuel system.You'llneed a diesel fuel biocide to sterilize your fuel system. Your dealer can advise you if you ever need this. If your fuel tank needs to be purged to removewater,seeyourdealeror a qualified service technician. Improper purging can damage your fuel system. 6-9