Changing the fuel filter in a Duramax Diesel 6.6 liter can improve your vehicle's fuel mileage and eliminate many problems with moisture in the fuel lines. The Duramax Diesel was introduced in 2001 to both Chevy and GMC trucks, and is made in Moraine, Ohio through DMAX--a joint operation between General Motors and Isuzu. Replacing the fuel filter should take approximately two hours, if you have never done this type of work before. All of the tools and parts necessary for this job are available at auto parts stores.
Open the hood of the vehicle. Locate the fuel filter on the side of the engine. Place the drain pan underneath the fuel filter.
Open the valve at the bottom of the fuel filter--the valve will release dirty fuel and water from the fuel filter. Allow draining for approximately two minutes.
Remove the electrical circuit, located at the bottom of the filter, from its wiring harness (this is known as the water-in-fuel sensor).
Remove the water-in-fuel sensor completely from the bottom of the fuel filter.
Spin the filter counterclockwise to remove it from the upper housing or fuel assembly. Use pliers on a filter that is stuck on or corroded.
Install the new filter at the top first. Spin the filter back into the upper fuel line and fuel heater assembly. Turn clockwise until you have about 30 foot-pounds of torque on the filter (the amount of torque you would use to tighten a screw).
Install the lower portion of the fuel filter assembly. Close the drain valve.
Pump the primer on top of the fuel filter assembly 30 times, or until the pump button gets hard to push. Start the truck and check for any fuel leaks. If the truck will not start, repeat the primer pumping until the primer button becomes stiff.
