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Robert, Mechanic
Category: Heavy Equipment
Satisfied Customers: 13518
Experience:  Experience with Cummins North West, Country Coach and Monaco repair.
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how do i prime a fuel filter for a duramax

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how do i prime a fuel filter for a duramax

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Here you go.


Fuel System Priming

Important: In order for the DURAMAX 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.


  1. Prior to priming the engine, ensure that the following has been completed:
    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 head and vent valve.
  2. Open the vent valve by turning the screw counterclockwise several full turns.

  3. Operate the priming pump until a small amount of fuel seeps from the vent valve. Allow the pump to return upward between pumps. When fuel is present, the filter is full of fuel and the system should be primed.
  4. Close the vent valve.
  5. Clean any fuel which accumulated on the fuel filter.
  6. Start the engine and allow it to idle for a few minutes.
  7. Check the filter for leaks.


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