How to Replace & Prime a Duramax Fuel Filter

by Grace Mclain
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The Duramax fuel filter is a diesel fuel filter that comes equipped on GM model trucks. The Duramax fuel filter is responsible for keeping sediments from the diesel out of the fuel injectors. If any of the sediments get inside the injectors, the injectors cannot disperse the diesel properly throughout the engine. The diesel flows through the fuel filter from the fuel tank. Once the sediments are trapped inside the filter, the cleaner diesel then flows to the injectors. Change the fuel filter between 25,000 and 35,000 miles as recommended by GM.

Step 1

Park the GM model truck in a well-ventilated location. Turn the steering wheel clockwise until it stops. This will position the front wheels to the far right position and make it easier to reach the fuel filter through the front wheel well opening. Turn the engine off and open the hood. Prop it up with the locking rod.

Step 2

Reach through the front passenger side wheel well and remove the plastic guard from the rear of the wheel well. The plastic guard is connected by small plastic clips that can be pried off the holes on the guard with a flat head screwdriver. Pull the guard out of the wheel well and place it on the ground. The fuel filter is now visible and accessible.

Step 3

Locate the water sensor on the bottom of the fuel filter. Follow the wires that are attached to the water sensor to the plug near the passenger side valve cover. Unplug the plug and position the water sensor plug and wires so they are hanging below the fuel filter.

Step 4

Position the drip pan under the truck in the area of the fuel filter. Slide the fuel filter strap wrench about halfway up the fuel filter. Turn the strap wrench counter-clockwise to loosen the fuel filter. Finish unscrewing the fuel filter with your hands and place it on the passenger side frame rail near the fuel filter housing.

Step 5

Move to the top side of the engine and pull the fuel filter out of the engine compartment. Pour the excess diesel into the drip pan. Remove the water sensor with the pliers. Screw the water sensor onto the new Duramax fuel filter. Tighten with the pliers. Discard the old fuel filter into the drip pan.

Step 6

Fill the new Duramax fuel filter with fresh diesel. Lower the new fuel filter through the engine compartment down to the passenger side frame rail.

Step 7

Move back to the front passenger side wheel well and screw the fuel filter onto the fuel filter housing. Turn the fuel filter clockwise to tighten. Finish tightening the fuel filter with the strap wrench. Turn the fuel filter one-half turn to properly seat the new fuel filter.

Step 8

Move back to the top side of the engine and open the relief valve on the top side of the fuel filter housing. Turn the relief valve counter-clockwise to open. This will allow the diesel to bleed out of the relief valve hole. Prime the new fuel filter by pushing in on the black primer cap on top of the fuel filter until the diesel starts to run out of the relief valve. Close the relief valve.

Step 9

Turn the ignition to the accessory position for about 15 seconds. Crank the engine. Inspect the new fuel filter for any diesel leaks. Turn the engine off. Reinstall the plastic guard back onto the rear of the front passenger side wheel well.

Step 10

Pull the drip pan out from under the truck and shut the hood.

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