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Car trouble is never fun, and sometimes simply replacing a part can go a long way to keeping a simple issue from getting worse and causing costly damage down the road. If you are experiencing problems, you may want to consider your fuel filter as one possible cause. Knowing when to change your filter and doing it sooner rather than later is an important part of vehicle maintenance. Below you will find an overview of exactly what role your fuel filter plays and how to tell if it is starting to go bad.

What Does Your Fuel Filter Do?

No matter where it comes from, any gasoline that you pump in your car will likely contain natural impurities, deposits, and contaminants that settle in the fuel tank and could potentially cause damage to parts like the fuel injectors. As you might guess, a fuel filter simply acts as a barrier, keeping potentially damaging elements from playing havoc on the rest of your vehicle. Since it does undergo a lot of heavy use during the regular lifespan of your vehicle, it slowly gathers and holds those contaminants, and eventually, if not attended to, will begin to restrict flow and eventually plug up.  

How often to replace a fuel filter can depend on a number of things. Fuel filters on older cars will often last one and a half to two years, but some can last longer. Some newer cars have “lifetime” filters that may be built into the fuel pump and do not need to be replace on a service interval. Check your owner’s manual to determine exactly how long the usefulness of your fuel filter lasts. If you end up with a tank of dirty fuel or start to notice symptoms that indicate the fuel you’re using is no longer being filtered properly, you may have to switch it out sooner than expected.

What Are Common Bad Fuel Filter Symptoms?

Your fuel system has a certain pressure that it needs to run it in order for fuel to properly mix with air, fire, and make power by creating the engine’s required air/fuel ratio. Restrictions in this fuel system, like a clogged fuel filter, drastically slow down this pressure, like a kink in a garden hose. 

There can be a variety of bad fuel filter symptoms, but one of the most common signs is a lack of power, or hesitation when you go to press the throttle down. In many seriously clogged fuel filters, you may not be able to press down the gas pedal farther than ¼” before the engine stumbles or sputters. If you experience these issues, understand that it could be other things, like ignition related, but if you a re troubleshooting fuel issues, the fuel filter is the first place to start. Even if you don’t notice that the engine feels different, you may see that your vehicle is running at unusual RPMs, dropping or spiking for what seems like no reason. It is also worth noting that the problems may occur off-and-on rather than consistently and just because your car runs better sometimes doesn’t mean that the issue isn’t present. 

Other, more subtle issues may also come up. You may find you get worse pedal response from your vehicle than usual. Your car may also be less powerful in general, and your Check Engine Light may turn on sporadically or remain on, and often can serve up a “lean” condition vehicle code. More serious problems can include the engine failing to start at all or completely losing power and dying while in use. While not always related to the fuel filter, all of these issues can be serious indications that something isn’t right. If you are experiencing these issues, and especially if you are seeing a combination of them, the filter is a potential cause that is not to be overlooked.

How Do You Replace a Fuel Filter?

If you see signs you need to change your fuel filter, then it’s probably time to start thinking about whether you can replace it yourself or if you need some professional help. While the exact process for changing the filter can vary a lot depending on your vehicle, it is possible to switch it out yourself. 

Remember, that you are going to be dealing with gasoline, and leaking gasoline once you crack open the fuel line, so exercise extreme caution! Be sure to read your repair manual or consult online how to properly relieve the fuel system of pressure before cracking open the fuel line, or what steps need to be taken to open the fuel system. 

The most common location for a fuel filter is in one of the fuel lines coming from the fuel tank, mounted near the tank on the vehicle’s frame. Several are also located inside the engine compartment, while others are non-serviceable and located within the fuel pump assembly, in the fuel tank. 

Most fuel systems on cars built in the last 20 years have quick-connect clips or unions that hold the lines together, and hold the fuel filter in-line for a leak-free seal. With the right tools, such as OEM 25150 or 24681, you can disconnect these fittings. Keep in mind, they can often be tricky to disconnect. If you do not have a lot of experience with fuel system maintenance, it may be best to get help from a professional mechanic, which you can search your area for one of our Preferred Shops here.  

Keep in mind, a fuel filter is made to be a service-interval part, rather than a failure part. Follow your vehicle’s OEM guidelines (check the owner’s manual) on when to change a fuel filter, or, if you’ve purchased a vehicle with over 100,000 miles and no indication the fuel filter has been changed, it’s a great idea to change it. The good news is that fuel filters can be a relatively affordable part, especially if you buy the parts and do the work yourself. A new filter can cost as little as around fifteen dollars in some cases, and even if you go to a pro, the costs of a replacement generally stays around $200.

How to Check a Fuel Filter

Once you remove a fuel filter, you can tell whether it’s the source of your problem by a simple blow-test. 

First, attempt to drain all the gas out of the fuel filter the best you can. Find the inlet to the fuel filter (should be labeled as either “in” or have an arrow pointing to the direction of the fuel flow) and clean that inlet with a shop towel.

Now, place a disposable rag or shop towel on your workbench, and gently blow into the inlet of the fuel filter, aiming down towards your shop rag on the bench. You should be able to easily blow into the filter without much resistance. With a plugged fuel filter, you won’t be able to. With a heavily restricted or clogged fuel filter, it will be hard.

Remember, gasoline is gross, doesn’t taste good, and is flammable, so be sure to exercise extreme caution. Leave any rags or towels long enough to dry outside before disposing them, and NEVER throw any old fuel or rags wet with gasoline into the trash.

Keeping Up with Fuel Filter Maintenance

Fuel filter problems generally won’t happen with proper maintenance. If you start noticing problems with your engine running strangely and experience loss of power and poor gas mileage, the fuel filter is a likely suspect on the fuel side, and an easy one to check off and change. 

Luckily, a new fuel filter should not cause too much of a dent in your bank account and even if you find that it doesn’t solve the issue, you are still replacing a maintenance item that needs to be replaced soon enough. Following the recommended change intervals in your owner’s manual is key to maintain optimal vehicle health, and in this case, the health of your fuel system. Waiting until you are starting to experience issues with your fuel filter may cause bigger fuel delivery issues to deal with beyond a clogged filter. 

For any advice on recommended maintenance, like fuel filters, come see us at any AutoZone location.  

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