GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Denali 🢒 Engine 🢒 Engine Controls and Fuel - 6.6L (LMM) 🢒 Fuel System Priming

Important: In order for the diesel fuel system to work properly, the fuel lines must be full of fuel and contain no air. If air gets into the fuel lines, it will be necessary to prime the fuel system to eliminate the air before operating the vehicle. Air could have entered the system in one of the following ways:

   • The vehicle ran out of fuel.
   • The filter was removed for service or replacement.
   • The fuel lines were removed or disconnected for servicing.
   • The fuel filter water drain cock was opened while the engine was running.
If one or more of the above occurred, air has entered the fuel system and you will need to prime the system prior to operating the vehicle.


    Object Number: 1871601 Size: SH
  1. Prior to priming the fuel system, ensure that the following has been completed:
    2. • There is fuel in the fuel tank.
    • The fuel filter has been installed and properly tightened.
    • The fuel lines are properly connected.
    • The fuel filter is cool to the touch.
    • Any dirt or debris has been removed from the fuel filter adapter and vent valve screw.
  2. Remove the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement .
  3. Open the vent valve screw (1) by turning the screw counterclockwise several full turns.

    4. Object Number: 1871603 Size: SH
  4. Operate the priming pump (1) until a small amount of fuel seeps from the vent valve. Allow the pump to fully return upward between pumps. When fuel is present, the filter is full of fuel and the system is primed.
  5. Close the vent valve screw.
  6. Clean any fuel which accumulated on the fuel filter adapter.
  7. Install the air cleaner outlet duct. Refer to Air Cleaner Outlet Duct Replacement .
  8. Start the engine and allow the engine to idle for a few minutes.
  9. Check the fuel system for leaks.