When a fuel filter malfunctions, your engine will receive the wrong fuel/air mixture. And if that happens, it can lead to loss of power, stuttering of the engine, as well as a complete breakdown of your car.
It would be a shame to let such a simple and inexpensive part ruin your car.
In order to prevent such consequences, I’ll guide you on how to change your car’s fuel filter.
- How Does a Fuel System Work?
- When to Change Your Fuel Filter
- Tools Needed for Changing the Fuel Filter
- How to Change Your Fuel Filter (Step-by-Step)
- Final Tips and Safety Precautions
How Does a Fuel System Work?
Before the fuel in your tank goes to your engine, it has to go through other components first. Those include:
In all internal combustion vehicles, fuel is stored in a separate tank. For safety concerns, it’s located as far away from the engine as possible.
To run the fuel all the way from the fuel tank to the engine, a pump located next to the fuel tank is used.
The lines go under the car between the pump and the engine.
Finally, we’ve come to our point of interest. Even though petrol companies assure everybody that their fuel is perfectly clean, that is usually far from the truth. It’s not uncommon to find particles of dirt, grime and other impurities in the fuel.
To stop the dirt and grime from getting to your engine and clogging it up, car manufacturers place a fuel filter in between the tank and the engine. Naturally, over time, the filter clogs up with all the impurities in the fuel, and you have to replace it. Additionally, the fuel filter can usually house certain sensors and monitors, such as a flex fuel sensor or a fuel pressure sensor.
Fuel Injectors (Carburetor)
The fuel finishes its long road either in the fuel injectors (in most modern vehicles) or in a carburetor (older vehicles and motorcycles). In the case of fuel injectors, they squirt the fuel at high pressure into the engine cylinders, while the air is supplied through the air valve. On the other hand, a carburetor mixes the air and fuel before the mixture goes through the valve into the cylinder.
When to Change Your Fuel Filter
The standard recommended service period for the fuel filter is around 30,000 miles (50,000 km), and it’s included in the regular service inspection list at most dealerships and mechanic shops.
However, if you prefer to work on your vehicle by yourself, here are a couple of common signs that you need to change your fuel filter. In most cases, your car will show loss of power at a steep incline or during hard acceleration.
Sometimes, a bad fuel filter makes the check engine light go off, and people forget that the filter could be the cause of that. A few engine inspections later, they realize it’s an easy and cheap fix they could have performed themselves.
Tools Needed for Changing the Fuel Filter
As I previously mentioned, changing your car’s fuel filter is a relatively cheap and easy fix. Most of the things you need, such as car jacks or a socket wrench, you probably own already.
In order to lift your car up, you need a set of car jacks. Be careful when jacking up your car and place the jack where it can handle the weight of your car.
You should never trust car jacks to support the weight of your car while you work on it. When you lift your car up, you should place the jack stands and then lower the car from the jacks, leaving it on stands only.
In order to disconnect your car battery, you need a socket wrench. Check the nut on your battery’s negative terminal and decide what kind of wrench you need.
You’ll need it either to disconnect the fuel line clips or to get to your fuse box. In any case, if you’re using it to pry plastic, it’s useful to wrap some electrical tape around it. It’ll keep the plastic free from scratches.
You’ll need it the most for plugging your fuel lines when removing them, to ensure no fuel gets spilled on or around you.
A Bucket and Some Rags
You really don’t want any fuel on the ground or all over yourself, so it’s best to catch any fuel in a bucket and get rid of it safely. Please don’t reuse the fuel you catch, since it’s probably full of dirt particles. Use the rags to wipe off any leftover fuel.
While not crucial to the task, fuse pullers are a handy tool to have, especially when the fuses are placed in a tricky spot. Also, they’re a godsend if you have big, clumsy fingers like me.
Extra Fuel Line Clips
You should have them in case you break the old ones while removing them.
Replacement Fuel Filter
Make sure you have your new filter prepared. Additionally, if you only want to clean your fuel filter, there’s a guide on how to do it in the link. In that case, you can remove the new fuel filter from the list.
If you own a diesel-powered car, the fuel filter most probably also houses certain sensors, such as a flex fuel sensor. If that is the case, you may need additional tools to remove them. Fortunately, a flat-head screwdriver will be enough in most cases.
How to Change Your Fuel Filter (Step-by-Step)
1. Release the Fuel Pressure
To ensure the least amount of fuel is in the lines when you disconnect them, here’s a trick on how to drain your fuel lines beforehand. This step, while optional, is recommended to minimize any risks.
You start by removing the fuse for your fuel pump. Consult your owner’s manual to locate the fuse box and identify the fuse itself.
Once you remove the fuse, start your car and let it run for a minute or two. There should be enough fuel in the lines to power the car for a short amount of time. Try not to run the car until it sputters out, but it’s no big deal if you do.
Afterward, put the fuel pump fuse back in.
2. Disconnect Your Battery
You don’t want any power going to the car while you’re working on it. A simple way to handle this is to disconnect the negative terminal on your battery.
It’s probably protected with a nut which you’ll have to undo with your socket wrench. Once you remove the nut, you can simply remove the wire from the terminal. Be sure to tuck the wire in a location where it can’t make contact with the terminal.
3. Lift the Car Up
Using your car jacks, lift the car up a bit above the height of your jack stands. The best way to lift your car is to go diagonally, lifting up opposite corners of the car at a time.
Once the car is up, place your jack stands in their respective locations. Afterward, lower the jacks so that the car sits on the stands only.
Car jacks are meant to be used for short periods of time, only in case of an emergency. You should never work under a car that is supported only by car jacks. Use jack stands to ensure your safety.
4. Disconnect the Fuel Lines
When the car is on the stands, it’s time to locate your fuel filter. Once you find it, you should place your bucket directly underneath the filter. It’ll ensure that any fuel spills go into a safe container.
After that, you should remove the clips that secure the fuel lines to the filter. They’re usually made of plastic, so be careful when removing them. If you happen to break them in the process, use a spare one you got previously (in the list above).
Once the clips are removed, pull the fuel lines out and point them towards the bucket. Be careful, since the fuel can still be under high pressure. Let the fuel run out into the bucket. After it does, it’s best to plug the lines with some electrical tape.
5. Remove the Old Filter
Once you drained all the fuel, it’s time to remove the filter. Take notice that the filter has a slightly conical shape, so it can only slide out one way. Make sure not to force it and try to see which way it goes out before you start yanking it.
If you see any electrical wires and clips going into the filter, make sure you undo them before you remove the filter.
Some fuel filter housings have a bolt running through them to additionally secure the filter itself, so be sure to check for a bolt before you try to pull the filter out. If it does have a bolt, undo it first.
6. Replace the Filter
For starters, you should visually compare your replacement filter with the old one. Make sure that the size and nozzles are the same. If the filter has any specs on it, make sure that they match with the old filter.
When replacing the fuel filter, make sure that you place it the right way, since putting it the wrong way will probably damage the housing. As I said, the fuel filter can only go in one way.
Reconnect the sensor clips if you had any, and tighten up the securing bolt if it exists. Try to shake or move the filter to ensure it fits securely.
7. Reconnect the Fuel Lines
Firstly, remove the electrical tape from the ends of the lines. After you’ve made sure that they fit snugly on the nozzles, connect the fuel lines to your new filter.
Make sure that you put the fuel line clips back on. Forgetting to clip your lines can result in some catastrophic consequences. Your fuel pump will probably die eventually, and you’ll be left stranded waiting for the tow service in the middle of the road.
8. Lower the Car and Reconnect the Battery
Once you have successfully replaced your fuel filter, it’s time to put your car back on the ground. Using your car jacks, lift the car so that it clears the jack stands. Afterward, remove the stands and slowly lower your car down.
Reconnect the wire to the negative terminal on your battery, making sure that you tighten the nut protecting the negative terminal.
9. Prime Your Fuel Pump to Get the Air Out
If you’re worried about air getting trapped in your fuel lines, you can prime your fuel pump to remove any air from the lines before you start the car.
To be perfectly honest, you don’t need to do this in most modern vehicles. Almost all of them have an air bleed valve which gets all the air out of the lines before it gets to the engine.
To prime your fuel pump, simply locate the pump in your vehicle and press the prime button on it. Once you’ve done that, you’ll be perfectly safe. You can now start your car without any concerns.
Final Tips and Safety Precautions
Working on your car’s fuel system is a particularly risky job. Honestly, if you don’t have experience working on cars, you should leave the job to the professionals.
Even though the steps are simple, the biggest issue is ensuring everything is connected and secured properly. A mistake in the fuel system can lead to fuel pump failure, engine failure, not to mention the risk of fire and serious injury or death.
Just to be clear, it’s not my intention to scare you away from working on your car. I just want you to be aware of the risks you face when you’re doing it. That should make you more careful while you do what needs to be done to keep your car running smoothly and safely.
If you’re working on a diesel-powered car, be aware that the fuel pressure is much higher than it is in gasoline powered engines. If you don’t release some of the pressure, you could injure yourself when disconnecting the fuel lines. Please take care.
Please ensure that your replacement fuel filter matches the one you already have. Check if the nozzles match, as well as if the filter fits the housing on your car.
Beware of the fuel and its fumes. It would be great if you had a fire extinguisher nearby.
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