The Ultimate Guide To Changing Your Fuel Efficiently And Safely

Changing a fuel filter is a simple process that can be done at home or by a mechanic. It is an important part of regular car maintenance, as it ensures that your engine runs smoothly and efficiently. A fuel filter strains the fuel before it passes to your engine, catching dirt, dust, rust and debris that could otherwise clog your injectors or damage your engine. This results in better fuel efficiency and restores the engine's original power.

How to Change a Fuel Filter

Relieve the pressure in the fuel system

Relieving the pressure in the fuel system is an important step when working on the fuel pump, fuel injectors, lines, and other related components. Here are some ways to do this:

Using the Fuel Pressure Regulator

First, disconnect the negative battery cable using a wrench to prevent sparks which could ignite fuel and fuel vapors. Then, locate the fuel pressure regulator on the fuel rail, which is mounted along the top area of the engine. Ensure that the regulator is vacuum-operated. With your hand, remove the vacuum hose from the top of the fuel pressure regulator. Next, connect a hand-operated vacuum pump to the top of the pressure regulator and apply about 16 inches Hg of vacuum to push the fuel in the lines back into the fuel tank.

Using the Fuel Pump Connector

Access the sending unit/fuel pump assembly on top of the fuel tank. Some vehicle models provide an access door to the fuel tank through the floor underneath the rear seat or under the trim in the trunk. For other models, you may need to raise the rear of your vehicle using a floor jack and support it on two jack stands to access the sending unit/pump assembly. If there is an access door above the tank, remove the rear seat or the trim on the floor of the trunk to access the fuel tank. Then, remove the mounting screws on the fuel tank access door. If the fuel pump is accessed from underneath, locate the fuel pump assembly after ensuring the vehicle is secured on the jack stands. Once you have accessed the fuel pump, simply unplug the fuel pump electrical connector on the sending unit/pump assembly.

Using the Fuel Pump Fuse and Relay

Locate the fuel pump fuse, which is usually under the dashboard or in the engine compartment, often on the driver's side of the vehicle. It is typically marked for easy identification and can also be found with the help of your owner's manual. Remove the fuse with your hand or a pair of pliers, or simply remove the fuel pump relay.

Using the Ford Inertia Switch

Search for the inertia switch around the trunk, rear compartment, or under the dashboard. Many Ford models use this shut-off switch to cut off fuel to the system in case of an accident. Consult your owner's manual if you need help locating it. Once located, simply unplug the inertia switch's electrical connector.

Using the Test-Port Valve

Disconnect the negative battery cable and locate the Schrader valve on the fuel rail around the top of the engine if your vehicle is equipped with a fuel injection system. Some models use this valve for test purposes, and it resembles the air valve on a bicycle tire. Unscrew the valve cap if there is one, and wrap a shop rag around the port valve to catch the squirt of fuel that will come out as you depressurize the system. Push the valve in using a small screwdriver until fuel stops pouring out of the valve, and then replace the test-port valve cap.

Disconnect and remove the old filter

Disconnecting and removing the old fuel filter is a relatively simple process, but it requires careful attention to safety procedures. Here is a step-by-step guide:

Disconnecting the Old Fuel Filter

Before beginning, ensure you are wearing the appropriate safety gear, including safety glasses and gloves, as you will be working with flammable materials. It is also important to work in a well-ventilated area to avoid the accumulation of combustible fumes.

First, relieve the pressure in the fuel system. This is done by removing the fuel pump fuse or relay and running the engine until it stalls, as the fuel pump will not be operating. Once the engine stalls, shut off the ignition and replace the fuse or relay.

Next, disconnect the battery. Loosen the nut holding the cable onto the negative terminal and tuck the negative cable to the side, ensuring it does not touch the terminal. This will prevent the engine from being started accidentally while you work.

Removing the Old Fuel Filter

Place a bowl, bucket, or drip pan under the fuel filter to catch any spilled fuel. Be careful to use a container that is suitable for holding gasoline, as it may eat through some types of plastic.

Remove the clips holding the fuel filter in place. These are usually plastic clips located on either side of the cylindrical fuel filter. Use a flat-head screwdriver to pop them out of the holes. Be aware that these clips are prone to breaking, so purchase replacements along with your new fuel filter.

With the clips removed, carefully slide the fuel lines off the nozzles on either end of the fuel filter. Tip the fuel lines toward the container to catch any spilled gasoline. Wear eye protection and gloves during this step to protect yourself from fuel splatter.

Finally, slide the fuel filter out of its bracket. The fuel filter is typically held in place by a metal bracket that wraps around its outer housing. It may have a slight bell shape, allowing it to slide out in only one direction. If necessary, push the filter toward the front or back of the car to remove it.

Now that the old fuel filter has been successfully disconnected and removed, you can proceed to install the new fuel filter.

Check for contamination

Checking for contamination in your fuel is an important step in maintaining your vehicle. Fuel contamination can cause serious issues, from reduced engine performance to a complete breakdown. Here are some detailed steps to help you check for contamination:

Understand the Types of Contamination

Fuel contamination can come in various forms, including particulate, water, and microbial contamination. Particulate contamination is mainly caused by rust and scale, but can also include airborne matter, rubber particles, fibres, and microbial by-products. Water contamination is common in stored fuels, and even a small amount of water can facilitate microbial growth. Microbial contamination, often referred to as "jet fuel fungus" or "diesel bug," is caused by microorganisms such as bacteria, yeasts, and fungi that enter the fuel from the surrounding atmosphere.

Observe Visual Clues

One of the simplest ways to check for contamination is through visual observation. Particulate contamination, for example, can often be detected by simply looking at the fuel. Additionally, fuel filters in older vehicles are sometimes made of transparent plastic, allowing you to see any build-up of contaminants.

Test for Water Contamination

Water contamination can be detected through simple, commercially available water tests for fuel. These tests will indicate whether the water content in your fuel is above or below a certain threshold, typically 30 parts per million.

Perform Microbial Fuel Contamination Tests

To check for microbial fuel contamination, you can use specialised fuel tests like the FUELSTAT® 15-minute jet fuel test. This test is an immunoassay antibody test that detects all dangerous microbes in aviation fuel. It is simple to use and can be performed on-site, providing results in just 15 minutes.

Monitor Engine Performance

Contaminated fuel can lead to noticeable changes in your engine's performance. Soon after refuelling with potentially contaminated fuel, pay attention to any unusual behaviour, such as the engine running rough, lacking power, or being harder to start than usual. Other signs may include misfiring, pinging, backfiring, or the "check engine" light illuminating. If you observe any of these symptoms, it is important to have your vehicle checked by a mechanic as soon as possible.

Remember, regular testing of fuel samples is crucial to prevent the costly consequences of contaminated fuel. By following these steps and staying vigilant, you can help ensure that your vehicle runs smoothly and efficiently.

Install the new filter

Now that you have removed the old fuel filter, it's time to install the new one. Take the new fuel filter and position it in the same orientation as the old filter. This is important so that the fuel flows in the correct direction. You can identify the direction of the flow by looking for an arrow on the filter.

Next, reattach the fuel lines to the new filter. Ensure that the fuel lines are securely attached to the nozzles of the fuel filter. You may need to use thread sealant for this step, depending on your vehicle.

If your old filter was held in place by a metal bracket, slide the new filter into the bracket. Check that the filter is seated properly—it should only be able to slide out in one direction.

Finally, replace the plastic clips that secure the fuel lines to the filter. These clips are often thin and made of plastic, so handle them with care as they can break easily. If they do break, you will need to source replacements before driving your vehicle.

Once the new filter is installed, you can lower your vehicle from the jack stands and reconnect the battery.

Reinstall the fuse or relay

Now that you've relieved the pressure in your vehicle's fuel system, disconnected and removed the old fuel filter, and installed the new one, it's time to reinstall the fuse or relay.

To start, simply put the fuel pump fuse or relay back into the fuse box. Make sure the vehicle is off before replacing the fuse or relay. Do not start the engine again after inserting the fuse or relay.

Now, try starting the vehicle. If the vehicle runs normally and there are no fuel leaks from the new filter, you're done! Congratulations! You've successfully changed your fuel filter.

If there are any issues with starting the vehicle or if there are any fuel leaks, turn off the engine and check the connections. Ensure that all connections are tight and secure before attempting to start the vehicle again.

It is important to note that you should not drive your vehicle if there are any fuel leaks. If you are unable to resolve the issue and stop the fuel leak, you should seek professional assistance.

Frequently asked questions