Changing The Fuel Filter On A 2008 F250 Diesel: Step-By-Step Guide

Changing the fuel filter on a 2008 F250 diesel is a relatively simple task that can be done in a few hours. The process involves removing the old filter and replacing it with a new one, as well as cleaning and lubricating the necessary parts. This task requires a few tools, such as a 36mm socket and a 6mm Allen wrench, and it is recommended to have a bucket or tub to catch any draining fuel. It is also important to note that the fuel tank should be less than a quarter full to avoid a siphoning issue and potential mess.

Drain the fuel

To drain the fuel, you will need a bucket or tub, a 6mm Allen wrench, a 36mm socket, and a 24mm socket or 1/2" drive ratchet.

First, place the bucket or tub beneath the fuel pump, which is located under the driver's door on the frame rail. Next, locate the Allen plug on the side of the fuel pump. It is a small, brass plug. Using the 6mm Allen wrench, remove the Allen plug. With the bucket directly in place, drain the fuel/water completely.

Now, using the 36mm socket, remove the large black end cap on the end that is nearer to the engine. Note that the fuel filter will slide out along with the cap. Pull out the old filter slowly, allowing the fuel to drain back. You may need to use an extension on the 36mm socket to reach.

At this point, you can also open the drain on the HFCM (fuel pump) mounted on the inside of the frame rail under the driver's side and allow the fuel to drain out into a container.

Remove the old filters

To remove the old filters, start by placing a tub or bucket beneath the fuel pump, which is under the driver's door on the frame rail. On the side of the fuel pump, locate and remove the allen plug—the small, brass plug—using the 6mm allen wrench. With the catch bucket directly in place, drain the fuel/water completely.

Using the 36mm socket, remove the large black end cap on the end that’s nearer to the engine. Note that the fuel filter will slide out along with the cap. Pull the old filter and the o-ring from the cap, properly disposing of both.

Now, move to the secondary filter. Using the 24mm socket or ½" square drive ratchet, remove the black top cap. Remove the fuel filter from the housing and the o-ring from the lid. Using the turkey baster, drain the excess fuel from the housing. Insert the new secondary filter into the housing and install the new o-ring onto the lid.

Clean the filter caps and mounting areas

To clean the filter caps and mounting areas, you will need to remove the fuel filters first.

For the 2008 F250, there are two fuel filters: the engine-mounted filter and the HFCM (fuel filter cap) mounted on the inside of the frame rail under the driver's side.

Firstly, take a 36mm socket and slowly pull out the engine-mounted filter, allowing the fuel to drain back. Then, open the drain on the HFCM and let it drain out into a container. You can now remove the cap from the filter using a 36mm socket.

Now, you can begin the process of cleaning the filter caps and mounting areas. Use a clean, lint-free cloth to wipe down the filter caps and mounting areas, ensuring that they are free of any dirt, debris, or residue. Pay close attention to the threads on the filter caps, as these areas can accumulate debris and should be thoroughly cleaned.

Once you have finished cleaning, it is important to lubricate the O-rings with fuel and install new filters before reattaching the caps. Tighten the caps to 20 ft/lbs and cycle the key 6 times for 30 seconds each to purge air from the system.

Install the new filters

To install the new filters, you will need to have purchased a fuel filter kit. It is recommended to use Motorcraft or Racor replacement fuel filters. You will also need a bucket or tub to drain the fuel, and a coffee can or other leak-proof container to transport the old filter for disposal.

For the tools, you will need a 36mm socket, a 6mm Allen wrench, and a 24mm socket or 1/2" drive ratchet.

Installing the Primary Fuel Filter

• Place the tub or bucket beneath the fuel pump, which is under the driver's door on the frame rail.
• On the side of the fuel pump, locate the Allen plug—the small, brass plug. Using the 6mm Allen wrench, remove the Allen plug.
• With the catch bucket directly in place, drain the fuel/water completely.
• Using the 36mm socket, remove the large black end cap—on the end that’s nearer to the engine. The fuel filter will slide out along with the cap.
• Pull the old filter and the O-ring from the cap, properly disposing of both.
• Install the new primary fuel filter into the cap. Once seated properly in the cap, the new filter will snap into place.
• Install the supplied O-ring into position on the end cap.
• Insert the new filter and cap section into the fuel pump, using the 36mm socket to tighten the cap securely—torque to 19lb. per ft.
• Being mindful not to over-tighten or cross-thread it, reinstall the Allen plug.

Installing the Secondary Fuel Filter

• Using the 24mm socket or 1/2" square drive ratchet, remove the black top cap.
• Remove the fuel filter from the housing and the O-ring from the lid.
• Using a turkey baster, drain the excess fuel from the housing.
• Insert the new secondary filter into the housing.
• Install the new O-ring onto the lid.
• Reinstall the black top cap, using the 24mm socket or 1/2" square drive ratchet to torque the bolt to 124lb. per in. (or approximately 10–111lb. per ft.).

Priming the Fuel System

After installing both new filters, you must prime the fuel system and bleed out any air. Turn the ignition to the 'Run' position three separate times for 30 seconds each time. If you fail to properly prime the fuel system, it can cause serious damage to the injectors, and that damage might not be immediately detectable.

Prime the fuel system

To prime the fuel system of your 2008 F250 diesel, follow these steps:

Step 1: Prepare the necessary tools and materials

• You will need a 36mm socket, a 6mm Allen wrench, and a 24mm socket or 1/2" drive ratchet.
• Get a bucket or tub to drain the fuel and a coffee can or leak-proof container to transport the old filter for disposal.
• Purchase a fuel filter kit. It is recommended to use only Motorcraft fuel filters or Racor replacement fuel filters.
• Get some diesel fuel and a diesel fuel lubricity additive. Motorcraft offers a lubricity additive available at all Ford dealers.

Step 2: Locate the primary and secondary fuel filters

• The primary fuel filter is located under the driver's side door, on the frame rail.
• The secondary filter is located on the engine, sitting between the CAC tube and the air intake tube.

Step 3: Drain the fuel and remove the old filters

• Place the tub or bucket beneath the fuel pump, under the driver's door, on the frame rail.
• Locate the allen plug on the side of the fuel pump. Using the 6mm Allen wrench, remove the allen plug.
• With the catch bucket in place, drain the fuel/water completely.
• Using the 36mm socket, remove the large black end cap near the engine. The fuel filter will slide out along with the cap.
• Pull out the old filter and the o-ring from the cap, and properly dispose of them.
• For the secondary filter, use the 24mm socket or 1/2" square drive ratchet to remove the black top cap.
• Remove the fuel filter from the housing and the o-ring from the lid.

Step 4: Install the new filters

• Install the new primary fuel filter into the cap. Once seated properly, the new filter will snap into place. Install the supplied o-ring into position on the end cap.
• Insert the new filter and cap section into the fuel pump, using the 36mm socket to tighten the cap securely (torque to 19lb. per ft).
• Reinstall the allen plug, being mindful not to over-tighten or cross-thread it.
• For the secondary filter, insert the new secondary filter into the housing.
• Install the new o-ring onto the lid.
• Reinstall the black top cap, using the 24mm socket or 1/2" square drive ratchet to torque the bolt to 124lb. per in. (or approximately 10-11lb. per ft.).

Step 5: Prime the fuel system

• After installing both new filters, you need to prime the fuel system and bleed out any air.
• Turn the ignition to the "Run" position and listen for the fuel pump to start and stop. This should take about ten seconds.
• Turn the key to the "Off" position when you hear the pump shut off.
• Repeat this process four more times.
• Start the truck.

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