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• Locate the HFCM on the driver side frame rail between the engine and fuel tank.
• Remove the drain plug for the water-fuel separator and drain the fuel into a container (such as a quart mason jar). This tends to be a messy procedure, but you can minimize spillage by positioning the container close to the drain plug and allowing the drain plug to fall into the container. Allow the HFCM to drain completely, then fish out the drain plug and dispose of the fuel. The drain plug on the HFCM fuel-water separator drain uses a 6 mm Allen wrench.
• Once the HFCM has been drained completely remove the primary fuel filter cap with a 36 mm socket. Accessing the filter cap is more difficult on four wheel drive trucks; a breaker bar or box end wrench is slim enough the move into position. A standard ratchet tends to be too large.
• The fuel filter generally comes out with the cap; if it does not, remove it manually. You may need to separate the fuel filter from the cap in order to maneuver them both out of the frame rail.
• Remove the fuel filter from the cap by simply pulling it out. There is a retaining clasp on the fuel filter that snaps into the fuel filter cap.
• Remove and replace the o-ring from the fuel filter cap.
• Install the new fuel filter, minding the orientation of the locking clasp and the o-ring. The o-ring side of the fuel filter is not inserted into the cap. The fuel filter should lock into the cap.
• If you have a four wheel drive vehicle, you may need to assembly the fuel filter into the cap once both have been positioned back into the frame rail - you likely noticed that it is a tight squeeze between the cross member and drive shaft when the two parts are assembled.
Lightly coat both o-rings (cap and bottom of filter) of the new fuel filter with clean motor oil before installing into the HFCM. Torque cap to 19 lb-ft (25 N-m).
• Reinstall the fuel-water separator drain plug.
• The secondary fuel filter is located next to the engine oil filter on top of the engine. Remove the cap with either a 24 mm socket or 1/2 inch square drive. Using a square drive to loosen the cap has a tendency to strip/damage the plastic hex head overtime and using the appropriate socket is therefore advised (a 15/16" socket also fits rather well).
• Remove and discard the used fuel filter.
• Drain the fuel filter housing of any fuel. An oral syringe or turkey baster work well.
• Install the new fuel filter into the fuel filter housing.
• Remove and replace the o-ring on the fuel filter cap. Lightly coat the o-ring with clean motor oil, then reinstall the cap. Torque to 10 lb-ft (14 N-m); do not overtighten the cap.
• Turn the key into the "run" position (as you would to initiate the glow plug sequence) for 30 seconds, then back to the "off" position. Repeat this procedure a minimum of 3 times in order to prime the fuel system before starting.