Engine Controls - 6.0L - Alternative Fuels (Introduction): Maintenance GMC Sierra 3500

Draining Procedure

1. Relieve the CNG fuel system pressure. Refer to Fuel Pressure Relief Procedure .
2. Slowly loosen the in-line CNG filter drain plug allowing any remaining CNG fuel pressure to escape.
3. Remove the drain fitting and capture any fluids. Dispose of the fluid in a safe manner.
4. Install the drain plug using a new O-ring. Refer to Maintenance Items in General Information for the correct O-ring part number. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the drain plug to 48 N.m (35 lb ft).