Changing Fuel Filters: An Easy Diy Task?

Changing a fuel filter is a relatively simple task that can be completed in a few hours. It is an important part of regular car maintenance, as it helps to ensure that contaminants do not enter the engine, which can cause issues with performance and longevity. The fuel filter is typically located along the fuel line, either under the car or in the engine bay, and can usually be accessed by jacking up the car and locating the fuse box. Before starting, it is important to relieve the pressure in the fuel system to prevent fuel from spraying out. This is done by locating and removing the fuel pump fuse or relay, then starting the engine and letting it run until it stalls. The next steps involve removing the old fuel filter and installing the new one, ensuring that the arrow on the fuel filter points towards the engine, indicating the direction of fuel flow. Finally, the fuel pump fuse or relay can be reinstalled, and the engine can be restarted, checking for any leaks.

Depressurise the fuel system

Depressurising the fuel system is an optional step when changing the fuel filter, but it is important to do so to help minimise any spills when removing the old fuel filter. Here is a step-by-step guide on how to depressurise the fuel system:

Step 1: Loosen the Fuel Filler Cap

Loosen the fuel filler cap on the outside of your vehicle without removing it. Listen for the audible hiss to subside, indicating that the pressure in the fuel tank has been released.

Step 2: Locate the Fuel Lines

Locate the fuel lines that attach to your fuel filter. Note that the location of the fuel filter may vary depending on the vehicle. In some vehicles, the fuel filter is mounted underneath the vehicle on a frame rail, while in others, it is located in the engine compartment. Refer to your owner's manual or an auto repair manual for the specific location of your fuel filter.

Step 3: Loosen the Fittings of the Fuel Lines

Loosen the fittings of the fuel lines on the filter by turning them with a flare wrench in a counterclockwise direction, but do not remove the fittings completely. Wait several minutes for the pressure in the lines to release. Fuel will leak from the cracked-open fittings until the pressure is fully released. Use rags to clean up any spills.

Step 4: Remove the Fuel Lines (Optional)

If you are replacing the fuel filter, remove the fuel lines from the fuel filter. Otherwise, leave them loosened until your maintenance work is complete.

Step 5: Alternative Method

If you do not wish to loosen the fuel lines to release the pressure, you can try the following method:

• Start by locating the fuel pump relay fuse in your vehicle's fuse box, which may be located under the dashboard on the driver's side or under the hood.
• Remove the fuel pump relay fuse using a fuse puller.
• Start the vehicle and let it idle until it sputters and quits by itself.
• Turn off the ignition once the vehicle has stopped.
• Push the fuel pump relay fuse back into place in the fuse box once all maintenance work is completed.
• Turn on the ignition key and wait a few seconds for the fuel system to pressurise before starting the vehicle.

Depressurising the fuel system is a crucial safety step before performing any maintenance work on the fuel filter. It will help prevent a dangerous spray of fuel when you remove the fuel filter. Always refer to your vehicle's owner's manual or a trusted repair guide for specific instructions applicable to your vehicle's make and model.

Locate the fuel filter

Locating the fuel filter is the first step to changing it. The fuel filter is typically located along the fuel line, either under the car or in the engine bay. Check your vehicle's owner's manual for the specific location of your fuel filter. If you do not have an owner's manual, try referring to the auto maker's website.

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. Some vehicles may place the fuel filter in a different location, so it is important to refer to your service manual to find out for sure.

If the fuel filter is located on the underside of your vehicle, you will need to jack up the car to access it. Slide the jack under the 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 beneath it before working under the vehicle.

Remove the old fuel filter

To remove the old fuel filter, you will need to disconnect the battery and jack up your vehicle if the filter is underneath it rather than in the engine bay.

First, disconnect the negative terminal on the battery. Loosen the nut holding the cable onto the negative terminal with a hand or socket wrench, but you don't need to remove the nut completely. Disconnecting the battery will ensure the engine cannot be started during the rest of the process.

Next, locate the fuel filter. There are two common locations for fuel filters. The first is along the fuel line on the bottom of the car, just past the fuel pump. The second is in the engine bay on the line that leads to the fuel rail. Refer to your vehicle's service manual to find the exact location.

If the fuel filter is located on the underside of your vehicle, you will need to jack up the car to access it. Slide the jack under the 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. Never rely on a jack to support the weight of a vehicle while you work.

Place a bowl or bucket beneath the fuel filter to catch any fuel that spills out when you disconnect the filter.

Now, remove the clips holding the fuel filter in place. Most fuel filters have two plastic clips on either side of the cylindrical fuel filter. Use a flat-head screwdriver to pop them out of the holes. These clips are thin 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 off the nozzles on either end. Tip the fuel lines toward the bowl or bucket to catch any spilled gasoline. Wear eye protection and gloves to protect yourself from fuel splatter.

Finally, slide the fuel filter out of its bracket. The fuel filter is likely held in place by a metal bracket that wraps around its outer housing. It will have a slight bell shape, allowing it to slide out in only one direction.

Install the new fuel filter

Before installing the new fuel filter, compare its size and shape to the old one. Check that the nozzles are the same size and that it will fit into the bracket. If the fuel filters do not match, you will need to return the new one for the correct replacement filter.

Now, slide the new fuel filter into the bracket. The new fuel filter should easily slide into its bracket. If you have to force it, it is likely not the correct diameter. The fuel filter should stop when it is seated properly, as it should only be able to slide all the way out in one direction. Be careful not to damage the housing of the fuel filter, as that may cause a leak.

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 your filter was located on the underside of your vehicle, you will need to 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 project.

Test for leaks

Once you have installed your new fuel filter, you will want to test for leaks. This is important as a leaking fuel filter can cause a fire outbreak.

• Start your engine and let it idle. Check each fuel injector for signs of external leakage. If you notice any leaks, replace your O ring.
• Turn off the engine and put it in Park or neutral gear. Pop the hood and remove the negative battery terminal. If your air filter box is in the way, use a screwdriver to unscrew the fasteners that hold it.
• Disconnect your throttle socket or throttle cable. Remove all wires carefully.
• Disconnect the socket on your injectors. Unbolt the fuel rail and pull the rail off with an injector remover.
• Measure the fuel pressure using a syringe that has milliliters.
• Test the voltage on the injection sockets with a multimeter. Most vehicles have injectors with two pins. Ideally, you wouldn't want to see variations above 3.70 and 3.89.
• Remove the fuel fuse and examine it. You should see PINs 87 and 30. Note that these main fuel lines and their numbers may differ between vehicles. Contact the fuse to ensure your fuel runs steadily.
• Check the level of fuel that fills the syringe as you send current to each injector. Take note of each injector's spraying rate. You can fill the syringe up to 50 ml for a more accurate result.
• Record the time it takes for each injector to fill the syringe. Your fuel injectors may be leaking if they are spraying too much fuel or if you see large drops.

Frequently asked questions