Fuel filter replacement is a part of routine maintenance.
Whether your vehicle runs on gasoline or diesel, it is an occasional requirement. The frequency of replacement depends on the vehicle, so check your owner's manual. On gasoline engines, it's typically every 12,000 miles or every third oil change.
You can check whether the filter needs replacing by following the below replacement procedures and blowing through the filter to test resistance. If there is more than just a small amount, the filter is clogged and needs replacing.
What the Fuel Filter Does
Fuel filters remove water and particulate matter from the fuel before it reaches the engine to be burned. They help keep the engine clean and emissions lower. Most vehicles have one fuel filter, but some have two.
Removing the Fuel Filter
For this, we'll assume a gasoline vehicle. Diesel vehicles are similar, but usually easier as the filter is typically contained in a canister that spins off and on, making replacement easy. Gasoline engines will have either a carburetor or fuel injection. This will affect the type of auto fuel filter used, but the procedure for replacement is roughly the same.
The fuel filter is typically located either on the firewall of the car (back of the engine, opposite the dashboard) or under the carriage on the frame (usually about 1/3 of the way back underneath the passenger or driver's door).
Auto fuel filters come in two types: plastic in-line and metal pressure cans. The plastic ones will be on an older engine while the metal ones are used in fuel injected engines.
To remove the fuel filter, you'll need basic hand tools (wrenches, pliers) and you may need a specific filter wrench, depending on vehicle model and filter type (click here for more info).
Note: you should wear safety glasses and work in a well-ventilated area without any open flame.
If your vehicle is fuel injected, follow your instruction manual to depressurize the fuel system. Then, using a wrench, remove the fuel line from the top and bottom of the filter, taking care not to spray or spill fuel or let the filter drop when it is free. Replace with a new filter and gaskets (they usually come with the filter) and tighten the bolts to specification.
For a vehicle with a carburetor, unhinge the hose clamps and slide away from the connectors. Using your fingers or pliers, gently turn the hoses and pull them away from the connectors. When the hoses are off, release the clamp that holds the filter in place (typically a screw or spring connection) and remove and replace the filter. Note where the inlet and outlet go and replace exactly. Clamp the new filter, slide on the hoses and gently replace the hose clamps.
Once the new filter is on, start the vehicle. It will take a few cranks as the fuel system needs to push the air out.
Once started, let it idle for a few minutes and check your connections for leaks. Dispose of the old filters responsibly.
Typical fuel filters cost about $15 and a mechanic will generally charge about 1/2 an hour of labor to do the job - so expect a shop to charge $50 for the replacement.