Changing Fuel Filters: 2004 Cummins Step-By-Step Guide

Changing the fuel filter on a 2004 Cummins engine is a relatively straightforward task that can be completed in a few simple steps. First, locate the fuel filter on the driver's side of the engine, below the intake manifold. Next, drain the fuel by opening the water drain valve located at the bottom of the filter housing and collect the fuel in a catch pan or bucket. Once the filter is drained, remove the housing by unscrewing the cap and lifting the filter out. Install the new filter, ensuring that you replace and lubricate the canister O-ring. Finally, prime the system by cycling the key without starting the engine 10 to 20 times to allow the low-pressure fuel pump to fill the new filter and purge the system of air.

Drain the fuel

To drain the fuel from your 2004 Cummins, you'll first need to locate the fuel filter. The fuel filter on a Cummins engine is located on the driver's side of the engine, below the intake manifold.

Now that you've located the fuel filter, the next step is to find the water drain valve. This is situated at the bottom of the filter housing. Attach a hose to the nipple of the water drain valve and place the other end of the hose into a catch pan or bucket. Open the valve and allow the fuel to drain.

Once the filter is drained, you can move on to removing the filter housing. If you have a 5.9L Cummins, simply remove the cap and lift the filter out. For a 6.7L Cummins, you'll first need to unplug the water-in-fuel sensor before lowering the canister and filter out through the bottom of the vehicle.

Remove the filter housing

To remove the filter housing on a 2004 Cummins, first drain the fuel. There is a water drain valve located at the bottom of the filter housing. Attach a hose to this nipple and route it to a catch pan, then open the valve and drain the fuel.

Now you can remove the housing. On a 5.9L, the cap is removed and the filter is lifted up and out. On a 6.7L, you first need to unplug the water-in-fuel sensor before lowering the canister and filter out through the bottom of the vehicle.

The filter is reinstalled in reverse order; make sure to replace and lubricate the canister O-ring.

Prime the system

To prime the system, cycle the key without starting the truck 10 to 20 times. This will allow the vehicle's low-pressure fuel pump to fill the new filters with fuel and purge the system of air.

To prime the system, first, open the relief valve using a 1/2-inch nut driver or flat-head screwdriver. Then, manually depress the primer pump located on top of the filter housing. Keep doing this until all the air is bled from the filter. Finally, close the relief valve and the process is complete.

Clean the canister

To clean the canister, you will need to remove the old filter. This can be done by loosening the canister cap with a strap wrench and a socket. Be sure to have a catch pan or bucket underneath to catch any fuel that may leak out. Once the cap is removed, the filter can be lifted out.

The canister will likely be coated with dirt and debris, so it is important to clean it thoroughly before installing the new filter. This can be done with a soft brush or cloth, taking care to remove any built-up grime. It is also important to check for any damage to the canister, such as cracks or leaks, before reinstalling the new filter.

If the canister is difficult to remove, it may be helpful to have a spare water separator unit ready. This will allow you to attach the new filter to the separator unit before removing the old assembly, minimizing fuel leakage.

Once the canister is clean and dry, you can prepare to install the new filter. It is recommended to pre-fill the new filter with clean fuel before installation. This can be done by covering the centre hole of the filter with your thumb and pouring fuel into the smaller outer holes.

Finally, when installing the new filter, be sure to replace the old O-ring with a new one provided with the filter. Lubricate the O-ring with a petroleum-based lubricant before placing it in the groove of the filter lid. Thread the lid on by hand first to avoid cross-threading, then tighten it with a ratchet.

Refill the canister

To refill the canister, you should fill the new filter with clean fuel before installation. You can do this by covering the centre hole in the filter with your thumb and pouring the fuel into the smaller outer holes. Then, put the filter in the canister and tighten it by three-quarters of a turn after the gasket makes contact with the base. You can do this by hand.

After installing the new filter, you need to prime the system. To do this, cycle the key without starting the truck 10 to 20 times. This will allow the vehicle's low-pressure fuel pump to fill the new filter with fuel and purge the system of air.

You can also prime the filter by turning the ignition on and listening for the lift pump to cycle, then turning the ignition off and back on again to listen to the lift pump cycle. Repeat this process three or four times.

Some people also recommend bumping the starter to get the lift pump to activate. Wait until you hear it stop, then start the engine. If you forget to bump the starter, the engine will run and then die. To fix this, loosen the filter lid and bump the starter to create a fountain of fuel from the lid. Then, tighten the lid and start the engine.

If you have a CAT diesel engine, you can buy a manual prime pump from your local CAT dealer.

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