Just like your oil requires an oil filter to protect your engine from any contaminants and impurities that may be flowing through it, your fuel lines also need to have a filter in place to prevent any contamination from getting to your fuel injectors from the fuel tank itself. Your fuel filter will likely look something like a soda can attached along your fuel line somewhere between the tank and the engine. The location can vary greatly between one model of vehicle and another. On some vehicles it can be located under the car, while others it will be in the engine bay itself.
The fuel filter is a fairly simple piece of technology which mostly consists of nothing more than filter paper inside the unit allowing it to catch any contaminants and debris flowing through your fuel line. It's really not much different than a coffee filter in that regard. However, a fuel filter is certainly not designed to last the entire life of your vehicle. As a filter it's going to get dirty eventually and as it gets clogged with whatever it's managed to filter out of your fuel lines, it will need to be replaced before it gets so badly clogged that it starts to prevent the flow of fuel entirely. Before that happens there are some signs and symptoms you can be on the lookout for to let you know that you're going to need to replace your fuel filter with a new one to keep your fuel flowing freely. Remember, if fuel can't pass through your fuel filter, then you've got nothing to burn in the combustion chamber of your engine and your car simply won't work.
Signs of a Bad Fuel Filter
Before your fuel filter gets so badly clogged that it causes an engine to shut down you will have a few signs that will alert you to the fact that there's a problem and something needs to be done about it.
Difficulty Starting: Because a clogged fuel filter will impede the flow of fuel through your lines to the engine, one of the more common symptoms that you can be on the lookout for is problems just getting your car started. You won't be able to have the necessary amount of fuel flowing through the lines to the injectors to be sprayed into the combustion chamber which will make your vehicle struggle momentarily before it's finally able to build up enough pressure in the fuel lines to create a combustion reaction. Remember, if your filter is so clogged that no fuel can pass through it then you will simply not have an engine that you can start.
Engine Misfires: Much like the way a clog will prevent the fuel from getting to your engine to allow it to start, it will continue to struggle even after you get your engine started. This can lead to problems with bad performance and engine misfires as a result because your engine is going to constantly be struggling to get the required amount of fuel. If you're not able to have enough in the combustion chamber to create a combustion reaction, or if it struggles and is sprayed in at the wrong time then that results in a misfire. You'll especially notice this happening when you are pushing your engine such as going up an incline or trying to haul something behind you.
Lack of Power: When you notice that your car is struggling far more than usual, you’re having difficulties accelerating or maintaining normal speeds and it seems like you have to push your engine a lot harder the normal just to get the standard performance from it then that's also a potential sign that you're having a problem with your fuel filter preventing an adequate flow of fuel.
Dead Fuel Pump: A fuel pump’s job is, as the name suggests, to pump your fuel from the tank to the engine. However, if your fuel filter is clogged it's going to put undue stress on the pump. Your pump will try harder to meet the needs of your engine but since the clog isn't moving anywhere it will strain the pump to the point that it will finally burn out on you.
Bad Fuel Economy: At first it might seem like a clogged fuel filter would actually extend the life of a tank of gasoline for you. It seems like you're going to be using less gas, but in fact the opposite is true. Because less gas will be travelling from the tank to the engine, your engine is going to increase demand for fuel which puts more strain on your fuel pump to deliver. Your fuel pump will begin pumping fuel faster and you'll end up wasting more gas in the long run.
Engine Stalls: Along with the potential misfires that can be caused when your fuel filter is too clogged, because your engine is being deprived of the fuel that it requires to function properly at some point it's going to shut off on you entirely and stall out. This can be extremely frustrating and even dangerous if it happens while you're stopped in traffic somewhere. The more stress you put your engine under the more likely it is to stall out, so if you find yourself accelerating up a hill or trying to tow a trailer behind you it is more likely that the engine will fail as a result.
Check Engine Light: The bane of any driver is when the check engine light comes on the dashboard. It indicates that you have a problem somewhere under the hood, but in no way direction to what the source of it might be. The only way to know that it has anything to do with your fuel filter would be if you're experiencing a number of these other symptoms at the same time or if you happen to have access to an OBD2 scanner.
An OBD2 scanner, also known as an onboard diagnostic tool, is what a professional mechanic uses to diagnose a check engine light when it comes up on your dashboard. When you plug it into your car it will give you a code that relates to a specific problem, in this case alerting you to the fact that you have an issue with your fuel line somewhere. Although the versions of these that mechanics use can be quite expensive you can get a serviceable OBD2 scanner off of a site like Amazon.com for as little as $30. This can be an invaluable tool for anyone who has an interest in DIY car maintenance and repair.
What Does a Bad Fuel Filter Sound Like?
Another sign that you can be on the lookout for it to let you know you have a problem with your fuel filter is the sound it might be making. A clogged fuel filter will make a particular knocking sound after you have your car warmed up, possibly a ticking noise. This is because the filter has lowered the pressure in your engine which leads to the audible sound that it produces.
How Long Does a Fuel Filter Last?
A standard rule of thumb when it comes to replacing fuel filters is that they're going to last for about 2 years or 30,000 miles or so. It's not unreasonable that you can also get to around 50,000 miles out of a fuel filter as well. If you have a newer car this may not be the case and you might be able to expect a bit of a longer lifespan from your fuel filter but the best way to know for sure is to check your owner's manual. It will always have the most accurate information for your particular make and model of vehicle.
If you're not sure if your fuel filter needs to be replaced a mechanic is able to do something called a fuel pressure test to find out for sure. Because the fuel in your lines is coming from the tank into the injectors where it can spray in the combustion chamber to allow your engine to run, a clog in the fuel filter will throw this pressure off. When you get a mechanic to do a fuel line pressure test, they will be able to determine whether or not the filter is the source of the problem.
Fuel Filter Replacement Cost
Heading to a mechanic to get your fuel filter replaced will probably set you back about $100 to $150. That's going to include the cost of parts as well as labour. A fuel filter on its own is actually a fairly affordable item. You do need to make sure you're getting the exact right fuel filter for your make and model of vehicle because if it's not the right one it will not fit on your fuel line. However, if you go to AutoZone and search for fuel filters, you're going to see that they range in price from as low as around $5 to as much as $50.
It's possible that you could also save a bit of money on replacing your fuel filter if you opted to swap it out on your own rather than pay a mechanic to do it. If you have the time and the inclination to get it done, a $150 repair could suddenly only cost you about $5 depending on the price of the fuel filter that your specific make and model needs.
The most important thing that you're going to need to keep in mind if you're interested in replacing your own fuel filter is determining the location of the filter itself. As we said, they can show up in a variety of places throughout your vehicle including inside the fuel tank itself where the fuel line begins, further down the fuel line under your car, and attached to your engine in the engine bay. Where each one is located very much affects the overall process for removing and replacing the fuel filter.
Once you do know where to look to find your fuel filter the process of replacing it is generally not that hard regardless of the location. Essentially all you need to do is remove the fuel line at either end of the filter, pull out the filter itself, and then swap in a new one and reattach it. Of course it's a little more complicated than that and you can find some instructions for replacing your fuel filter here, as well as some handy videos made by professional mechanics that you can watch on YouTube so you can see the process step-by-step if you're unsure of what you need to do.
Remember that you're going to need to relieve the pressure in your fuel line before you remove the fuel filter and that's going to require you disabling your fuel pump temporarily and then relieving the pressure by running your engine for a short period of time first. If you don't do this, your fuel line will still be under pressure when you try to remove the fuel filter and you could end up causing an accident and spraying yourself with pressurised gasoline which is definitely something you don't want to be doing.
The Bottom Line
Like any filter in your vehicle, a fuel filter is a very simple piece of technology which is why some of them are so inexpensive to buy even brand new. But just because it's not very expensive or complicated does not mean it's also not important. Without a fuel filter in place the potential for damage to your engine caused by contaminated fuel potentially clogging up your fuel injectors and reducing the overall effectiveness of your engine is very high.
As simple as it is, the fuel filter is an important part of your vehicle and it needs to be well-maintained. Make sure you know how often your owner's manual recommends changing your fuel filter for a new one and keep up with maintenance to ensure that you're not overly straining your fuel pump, and your engine isn't being taxed by trying to struggle through in the fuel filter either.