1994 GMC Suburban Owner's Manual - Page 254

To drain water: 1. Stop and park the vehicle in a safe place. Turn off the engineand apply the parking brake. 2. Remove the fueltank cap. 3. Place afuel-resistant container under the filterdrain hose. 4. With the engine off, open the water drain valve 2 to 3 turns. When standing in front of the vehicle, thevalve is located on the right side of the thermostat housing. 5. Start the engine allow it to idleuntil clear fuel is observed. and 6 . Stop the engineand close the water drain valve. 7. Remove the fuel-resistant container and properly dispose of the contaminated fuel.To find outhow to properly dispose of contaminated diesel fuel see "What to Do withUsed Oil" in the "Engine Oil (Diesel Engines)" part, later in this section. 8. Install the fueltank cap. If the WATER IN FUEL light comes on again after driving a short distance or the engine runs rough or stalls-a large amount of water has probably been pumped intothe fuel tank. The fueltank should be purged.