Change Your Fuel Filter

1
Time to Replace Your Fuel Filter

Fuel filter ready for replacement.
This fuel filter is ready to change. photo by Matt Wright, 2007

What you'll need:

  • new fuel filter
  • new fuel line washers
  • open end wrenches
  • rags
  • eye protection

Your fuel filter is one of those engine components that may only cost $10 or $20, but can protect your engine from thousands of dollars in damage if you change it regularly. Fuel filters protect some of the very delicate parts of your engine. Carburetors and fuel injection systems can be clogged up by the tiniest of particles, so a properly functioning fuel filter is very important. If your fuel filter starts to get clogged up, the fuel trying to flow through the filter to your engine gets stuck in line like soccer moms at a 5 am Thanksgiving Day sale.

It only takes a few minutes to replace your fuel filter, and it should be replaced once a year on the average commuter vehicle. Replacing your fuel filter should be part of your car's regular maintenance schedule.

IMPORTANT: Do not skip the fuel system pressure release step. Injury and other damage can result! Also, please remember to work safely.

2
Safety Step! Relieving Fuel System Pressure

Fuel pump relay coming out.
Remove the fuel pump relay or fuse. photo by Matt Wright, 2007

  • allow engine to cool
  • relieve fuel system pressure
  • put on your eye protection

Before you begin the job of replacing your fuel filter, you must relieve the pressure in your fuel system. A fuel injection system operates under very high pressure. If you don't release this pressure before you start unscrewing fuel lines the result can be explosive. Do this before you attempt to change the fuel filter.

To release the pressure in your fuel lines (and fuel filter) you'll need to locate the fuel pump fuse in the fuse box. If your fuel pump doesn't have a dedicated fuse, find the relay that operates the fuel pump. Once you've found the fuel pump fuse or relay, start the car. With the engine running, pull the fuse or relay out. If you pulled the right one, the engine will sputter and die. Since it's using all of the pressurized fuel in the system, the fuel lines won't be pressurized when you open the fittings on your fuel filter.

 

3
Disconnect the Fuel Lines from the Fuel Filter

Remove this fuel line bolt. Fuel filter change.
Disconnect the fuel lines from the fuel filter. photo by Matt Wright, 2007

Now that you've relieved the fuel pressure you can remove the old fuel filter. If you didn't do this yet, you must go to the previous step and do it. Very dangerous!

If your car has fuel injection (most do these days) find two open end wrenches* that are the right size for the fuel filter fittings. They will be two different sizes in most cases. With the wrenches in place, put a rag over the fitting to separate your head from the fuel lines. This will further protect your eyes in case there is some pressure in the lines.

Hold the wrench that fits on the actual filter, and turn the other wrench counter clockwise until the special bolt (part of what's called a "banjo fitting") comes out. Slide the fuel line off the bolt and set the bolt aside. Now do the same for the other side of the fuel filter.

*Some vehicles require a special fuel line wrench to disconnect the lines, check yours out before you start this job. Proper tools for the proper job.

4
Remove the Old Fuel Filter

Unclamp the old fuel filter.
Unclamp the fuel filter. photo by Matt Wright, 2007

With the fuel lines disconnected from the fuel filter, you can remove the old fuel filter from the car. Most will be held in by a clamp that can be released using a flat head screwdriver.

*Important: Try to remove the old fuel filter carefully, it will probably still be full of gas!

5
Change the Fuel Filter Washers

Replace the washers on the fuel filter connections.
Replace the washers on the fuel filter connections. photo by Matt wright, 2007

Remember those special fuel line bolts you carefully set aside? With those will be a special pressure washer. They are usually either copper or aluminum. Remove the old washers and replace them with the new washers that match. The washers are usually different from one side of the fuel filter to the other. You'll place one washer on the bolt before you slide the fuel line on, and one after. Keeping track will ensure your new filter is leak free.

6
Install the New Fuel Filter

New fuel filter ready for action.
Your new fuel filter ready to go. photo by Matt Wright, 2007

Installation of the new filter is the opposite of removal. Don't forget to put the fuel pump fuse or relay back before you try to start the car. Now you've changed your fuel filter and can enjoy peace of mind and better gas mileage.