What Is a Fuel Filter?

A fuel filter is a component that helps ensure only pure gasoline enters the engine of your car, truck or SUV. When it is clogged, your vehicle may experience issues such as difficult starting, jerking while driving and even complete engine failure. A fuel filter acts as a barrier to keep small impurities from damaging components such as the fuel pump and fuel injectors.

When you fill up your tank, tiny paint chips, dirt and rust from the underground fuel containers can make their way into your gas line. Over time, these contaminants slowly build up, restricting the flow of gasoline and causing damage to your car or truck. A fuel filter prevents these harmful impurities from entering your engine, by trapping them in a fine film before they can reach the fuel injectors and other vital components.

Fuel filters can be found either in the fuel tank or in the gas line between the fuel tank and the engine. They are typically cylindrical in shape with an inlet and outlet for the entrance and exit of fuel. They are also often fitted with a pressure gauge to monitor the pressure in the filter, and an arrow to indicate which direction the fuel is meant to flow.

The main component of a fuel filter is its filtration medium, usually made from a special paper with pores that can catch impurities. This is housed in a plastic or metal container and connected to the fuel lines with either a single or dual fuel line connections. Some fuel filters are canister-style, while others are cartridge-style and designed to be replaceable. Some are used only once, while others can be replaced many times over the lifetime of your vehicle.

There are many different types of fuel filters on the market, from a simple spin-on model to high-performance diesel filters. The important thing to look for when buying a fuel filter is its absolute micron rating, which indicates how effectively it catches particles of a certain size. A lower value means that the filter is less effective at catching smaller particles, while a higher value implies that it is more efficient.

You can tell if your fuel filter is clogged by performing a simple blow test. Using a shop towel, try to blow air through the filter’s inlet and outlet ports. If you can’t do this, it is likely that the filter is moderately or severely clogged and needs to be replaced immediately.

If your car is having difficulty starting, a clogged fuel filter is a common culprit. The car will start, but it might take longer than usual because the fuel is having trouble making its way through the filter into the engine. A clogged fuel filter can also cause the engine to shake at idle, because it is starving for fuel.

The way to change a fuel filter is to follow your vehicle’s repair manual, or ask your local mechanic to guide you. You will need a screwdriver and possibly a fuel line separator tool to remove the old fuel filter. Be prepared for gasoline to spill out as you twist and pull on the nipples to break them off the filter. Be sure to install the new fuel filter with its arrow pointing the right way, and double-check that it is pointed in the correct direction of fuel flow (usually toward the engine).