What is a fuel filter and where is it located?

The fuel filter is the last line of defense for blocking particles in the fuel from reaching the engine and causing damage. No matter what type of fuel system is found in a particular vehicle, whether it be a high pressure fuel injected or a direct injected gas or diesel fuel system found in the more modern vehicles of today, or a carbureted system of yesteryear, it will have some sort of fuel filter. They are usually found along the fuel line, mounted underneath the vehicle or to the firewall—these are known as in-line fuel filters. Some vehicles may have non-serviceable fuel filters mounted inside the fuel tank, and these are known as in-tank fuel filters and are often referred to as a “strainer” or “sock.” Fuel filters have a mesh screen or pleated paper inside them to filter debris out of the fuel. Some diesel engines use a bowl-shaped fuel filter that is able to collect water at the bottom, separating water from the diesel fuel. The water can be released through a valve at the bottom of the filter. 

Dirt or grime can enter the fuel during refilling, while flakes of rust and sediment from the inside of the fuel tank can enter the fuel if the tank is corroding. These impurities will contaminate the fuel if allowed to flow freely. So, as you can imagine, it is important to filter out these types of particles regardless of the fuel system as bad fuel can damage fuel injector assemblies, fuel pumps, and carburetors equally due to the abrasive action these harmful contaminants have on these parts. Fuel filters also play a role in improving performance, due to the simple fact that the fewer contaminants there are in the gas or diesel fuel, the better it will flow, and the more efficiently it can be burnt.

How do I know if my fuel filter needs to be replaced?

Since the fuel filter’s job is to catch debris before it can reach the fuel pump, it naturally fills up with that material and can eventually become clogged. Deterioration or gelling of the fuel can also clog the fuel filter. Many mechanics recommend that you change the fuel filter any time a tune-up is done on the car or truck—usually every 3 to 5 years—or any time a fuel pump has been changed. The fuel filter has a limited lifespan and requires regular maintenance. Serviceable in-line fuel filters have predetermined service intervals recommended by the auto manufacturer, so be sure to consult your owners’ manual.

If this maintenance is not kept up, and the filter becomes clogged, it can cause a restriction in fuel flow, making it hard for the engine to draw precious fuel. This can make the car hesitate or jerk during acceleration or can make it stall out. If the problem gets worse you might not be able to start your car at all. A clogged fuel filter can also cause harm to the fuel pump.

Can I replace a fuel filter myself?

The process for replacing the fuel filter will vary from one model to another, but overall, it can be within the grasp of the do-it-yourselfer. For some models, specialty tools may be required, so consult a repair manual or a knowledgeable mechanic. Disconnect the battery to avoid any sparking occurring as you work on your fuel lines. 

You should be able to access the fuel filter either in the engine compartment or underneath the vehicle near the fuel tank. Before you disconnect the fuel lines that run into and out of the fuel filter, you’ll want to relieve the pressure in the fuel lines. Otherwise you’ll have fuel spraying everywhere, which would be unpleasant and potentially dangerous. You can do this by removing the fuel pump fuse and running the engine until it runs out of fuel and stops. 

With that done, you’ll have to disconnect the fuel filter from the fuel lines, dismount it, and attach the new one. While the old fuel filter is off, you may want to inspect the fuel lines. If they are hardened or cracked, they should be replaced. Depending on the application, a special fuel line disconnect tool may be required. Other applications may use threaded fittings that will require a flare nut wrench to remove without damaging the line or rounding the fitting.

Need a fuel filter replacement?

Take fuel, add in dirt and contaminants, and you’ve got a recipe for potentially disastrous results. That’s why a properly functioning fuel filter is extremely important, as it filters debris out of the gas or diesel fuel before it is able to cause any fuel efficiency problems, or damage to parts like the fuel injectors. At 1A Auto, we carry a large selection of fuel filters for carbureted and high pressure fuel injected engines, for many makes and models, all designed to meet the demands of your car or truck’s engine for proper fuel flow and filtration.

At 1A Auto, we make shopping for a replacement fuel filter for your gas or diesel fuel powered car, truck, SUV or van easy—we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our products, warranty, compatibility or to purchase, or you can buy online. Order your replacement fuel filter today and keep your carburetor or fuel injection system flowing freely!