Changing Fuel Filters: Kenworth Trucks Step-By-Step Guide

Changing the fuel filter is a part of regular maintenance for gasoline engine vehicles. It is important to keep your fuel system properly maintained by changing the fuel filter to prolong the life of the fuel pump. Dirt in the fuel is captured by the filter, which clogs over time, causing it to operate less efficiently. The clogged filter reduces fuel pressure and volume in the fuel system. If your vehicle is losing power, it could be a sign of a clogged fuel filter. Replace the filter at the manufacturer’s recommended interval.

Relieve the pressure in the fuel system

To relieve the pressure in the fuel system of your Kenworth, follow these steps:

Firstly, locate your vehicle's fuse box. This is necessary because relieving the pressure in the fuel system requires running the vehicle without the fuel pump functioning for a short time. The fuse box will be located either in the interior of the car or under the hood. You can refer to your vehicle's owner's manual to locate the appropriate fuse box. If you do not have access to the owner's manual, try checking the auto maker's website. Typically, the fuse for the fuel pump is found in the fuse box located inside the vehicle.

Once you have located the correct fuse box, use the diagram provided on the fuse box cover or in the owner's manual to identify the fuse that powers the fuel pump. This fuse is responsible for supplying electricity to the fuel pump, allowing it to operate. Remove this fuse using a pair of needle-nose pliers or plastic tweezers. With the fuse removed, the fuel pump will be temporarily disabled, even when you start the engine.

At this point, ensure that your vehicle is not in gear. Although the engine will not receive fuel from the gas tank due to the removed fuse, there may still be residual fuel in the lines, allowing the engine to start and run briefly. For automatic vehicles, make sure the gear is in the "park" position. For vehicles with a standard transmission, put the gear in neutral and engage the parking brake. Taking these precautions will prevent the vehicle from moving unintentionally, even if the engine starts.

Now, start the engine by inserting the key into the ignition and turning it as you normally would. The engine should start without any issues as it consumes the remaining fuel in the fuel system past the fuel pump. If the engine turns over but then stops suddenly, it may indicate insufficient pressure in the fuel lines, preventing adequate fuel delivery to the engine. On the other hand, if the engine continues to run, let it operate for about a minute before shutting it off manually. Running the engine for a short duration will help relieve the pressure in the fuel lines. However, it is not necessary to let the engine run until it dies, as this may cause difficulties in restarting it.

Finally, with the engine off, re-insert the fuel pump fuse into the fuse box. Make sure the vehicle remains off before replacing the fuse. Do not start the engine again after inserting the fuse. By following these steps, you will have successfully relieved the pressure in the fuel system of your Kenworth, preparing it for further maintenance or repairs.

Remove the old fuel filter

To remove the old fuel filter, first disconnect the battery. Loosen the nut holding the cable onto the negative terminal with a hand or socket wrench. Tuck the negative cable to the side of the battery to ensure it doesn't touch its terminal.

Next, locate the fuel filter. Refer to your vehicle's service manual to help you find it. The most common location for modern vehicles is along the fuel line on the bottom of the car, just past the fuel pump. In some vehicles, the fuel filter is located in the engine bay on the line that leads to the fuel rail. You may need to access the fuel filter from inside the cabin of some vehicles, or jack up the car if the fuel filter is located on the underside of your vehicle. If you need to jack up the car, place a jack under one of its designated jack points and raise the vehicle. Once the vehicle is jacked up, place jack stands underneath.

Place a bowl or bucket beneath the fuel filter to catch any fuel that may spill out when you disconnect the filter. Remove the clips holding the fuel filter in place with a flat-head screwdriver. These clips are usually made of thin plastic and tend to break easily, so purchasing replacement clips along with your new fuel filter is advised.

With the clips removed, slide the fuel lines away from the filter and towards the bowl or bucket to catch any spilled gasoline. Wear eye protection and gloves during this step to protect yourself from fuel splatter. Remove the fuel lines from the nozzles on either end of the filter.

Finally, slide the fuel filter out of its bracket. The filter will likely be held in place by a metal bracket that wraps around its outer housing. The fuel filter will have a slight bell shape, allowing it to slide out in only one direction. If your filter sits in the bracket differently, you may need to slide it toward the back of the car to remove it. Some fuel filters under the hood may be held in the bracket with a bolt that will need to be removed.

Disconnect the battery

Disconnecting the battery is an important step when changing the fuel filter on a Kenworth, or any vehicle, as it ensures that the engine cannot be started accidentally. This is a crucial safety measure as you don't want the engine to turn on while you are working on changing the fuel filter.

To disconnect the battery, first, locate the battery. It is usually located in the engine bay, but if you are unsure, refer to your vehicle's manual or the manufacturer's website. Once you have located the battery, identify the negative terminal. This will be clearly marked, and you will need to disconnect the cable attached to this terminal.

Using a hand or socket wrench, loosen the nut that holds the cable onto the negative terminal. You do not need to remove the nut completely, just loosen it enough so that you can detach the cable. Once the cable is loose, carefully disconnect it from the negative terminal. It is important to only disconnect the negative cable and not the positive cable. Tuck the negative cable safely to the side of the battery to ensure it does not accidentally come into contact with the terminal.

With the battery disconnected, you can now proceed with the next steps of changing the fuel filter, knowing that the engine will not start accidentally. Remember to reconnect the battery cable to the negative terminal once you have finished working on the fuel filter and before attempting to start the engine again.

Locate the fuel filter

To locate the fuel filter, refer to your Kenworth service manual. The fuel filter is located in one of two common locations in vehicles. The most common location for modern vehicles is along the fuel line on the bottom of the car, just past the fuel pump. If your Kenworth falls into this category, you will need to jack up the car to access the fuel filter safely. Slide the jack under your car at one of its designated jack points, then either pump or twist the handle to raise the vehicle. Once the vehicle is jacked up, place jack stands underneath for added safety before working under the vehicle.

In some vehicles, the fuel filter is located in the engine bay on the line that leads to the fuel rail. You may need to access the fuel filter from inside the cabin of some vehicles.

Install a new fuel filter

To install a new fuel filter, first compare the new filter to the old one. Check that they appear to have the same outside diameter, that the nozzles are the same size, and that it will fit into the bracket. If the fuel filters do not match, do not install the new one as it is not the correct replacement filter.

Once you have confirmed that the new fuel filter is the correct one, slide it into the bracket. It should easily slide into place. Be careful not to damage the housing of the fuel filter, as that may cause a leak. If you find yourself pushing hard on the filter to make it fit, it is likely not the correct one.

Next, fasten the fuel filter to the fuel line. Slide the fuel lines onto the front and back of the filter the same way they were attached to the old one. With the fuel line in place on the filter, slide the plastic clips through the holes on the fuel line nozzle to secure the line in place on the fuel filter. Make sure the fuel lines are snug on the nozzles of the fuel filter before sliding the clips into place. If the plastic clip breaks as you slide it in, do not attempt to drive the vehicle until you replace the broken clip.

Finally, lower the vehicle off of the jack stands. Jack up the car to relieve the weight on the jack stands, then slide them out from beneath the vehicle. Once the jack stands are clear, lower the vehicle to the ground. Be sure the jack stands are completely out of the way, otherwise they may damage the vehicle if lowered onto them. Once the vehicle is safely on the ground, reconnect the battery to complete the installation.

Frequently asked questions