How To – Changing Your Cars Fuel Filter

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    Depending on your driving habits and the quality of fuel you put in your car it is a good idea to change your car’s fuel filter once every 12 to 24 months.

    Because the process is normally pretty easy it is something that you can do yourself with a couple hand tools and safety glasses.

    Before you start you will need to pickup a new filter at your automotive supply store (check our store for good deals).  You will need to tell the parts person your car Make, Model, Year and the size engine you have. Most of this information can be found in your owners manual or on the door tag of your vehicle.

    If you have difficulty figuring out what size engine you have because you purchased the car used then you can try to find the filter first and see if there is a part number that you can match. If not then drive by a dealer … look stupid and as a service rep to come look at your engine and give you the proper size and fuel injection type.

    For most cars there is only one fuel filter that is mounted on the rear firewall of your engine compartment.

    If you have a modified vehicle, Large truck or diesel engine you may need to hunt down your fuel filter.

    The easiest way to find your fuel filter is to find your fuel injector throttle body. This is where air and fuel is mixed and fed into your engine. Follow the black tube from your air filter box back to where it connects to your engine. This is where your throttle body is located.

    Now look for the fuel line that supplies fuel to your fuel rail or throttle body and injectors. This is a thick black rubber line about a half inch thick. Follow the fuel line away from the throttle body and it will lead you to your fuel filter.

    Some fuel filters are actually placed near the gas tank. This is not an optimal design and they really need to be replaced when on a car lift for safety reasons. You don’t want a lot of fuel leaking all over you while you work in a cramped area under your car. If you have this design bring it in and it should not cost more then a half hour of labor.

    Preparing to remove the old Fuel Filter.

    It is best to perform this work with the vehicle cold over night.

    Your fuel filter can hold about a pint of fuel so when  you are working on it you want to be careful not to spill it all over a hot engine. Also with the price of gasoline you don’t want to waste it … heh just kidding.

    The fuel filter should be securely attached to the fire wall with a band that can be taken off by removing a bolt. This is a standard bolt most likely a 10mm on non american cars or half inch.

    The bandjo fuel lines that attach to the filter are normally much larger expect a 14mm bolt.

    A small amount of fuel may come out if the line has pressure in it this is why you do this job with the car cold. You can also remove the gas cap to remove pressure from the system. Finally there is usually a bleed bolt on top of one of the fuel lines that you could open to remove pressure. Fuel will leak if you open this so have a can under the filter to catch the fuel.

    You should keep the filter attached to the firewall as you remove the fuel lines as this will allow you to break the fuel line bolts free and not need another pair of hands to hold it.

    Fuel lines use two copper washers to seal the connection you should have got a new set with your new filter. Be careful when removing the lines to not lose the copper washers. If you have a problem with the new filter you want to be able to put the old one back on and reusing these washers is normally ok if you have changed the filter recently (within a year).

    Take one line off at a time then attach it to the new filter by starting about half the threads. You want it secure but you also want it lose enough to position into place after you remove the old filter.

    When you have both lines attached to the new filter you can remove the old filter from the firewall.

    Have a coffee can or cut a milk jug in half to stick the filter in when you remove it .. there will be about a pint of gasoline in it.

    Secure the new filter to the firewall.

    Now you can tighten the banjo fuel lines to the filter. Do not over tighten just make them very snug.

    Testing your new Fuel Filter

    Now that your new fuel filter is in place and secure you can clean up whatever tools you have laying around and start your car to test it out.

    Expect the car to take a bit of cranking to get started. Remember the Fuel Filter is empty and it has to pump a pint of fuel into the filter and then more fuel up to your injectors. This should take 5 to 10 seconds at most…. not 30 seconds.

    Once your car is running allow it to idle for a few minutes then bring the rpms up to about 2000 rpm which is driving speed on the highway.

    Your engine should run smoothly.

    Final Note

    Changing your fuel filter should be done regularly and once you have completed the job the first time you will be more likely to do it yourself in the future.

    It is a little more complicated then changing an air filter or oil filter because it takes a little more care when dealing with a cup of gasoline mounted to your firewall but it is really not that bad.

    Remember don’t lose those washers and keep them even after the job is done.. you can’t just buy a set for 39cents and you may need them.

    The fuel in your fuel filter can be used in your lawn mower but I would not suggest you pour it back in your gas tank or try to fill the new fuel filter before you reinstall it. Gasoline will kill your grass so don’t pour it on your grass or under a bush or into your sink drain.. gees don’t do that. At worst let it sit and evaporate over a couple days some place outside where animals can’t get to it or just pour it on some dirt. You will probably have the EPA storm your house if you do that in California though so get rid of it how you think best.

    Some car manuals will suggest removing the ground wire from your car battery before you begin.. I have an apprehension about lose wires around gasoline but follow your manuals instructions or do as I did and make sure your keys are in your pocket not in the ignition so that the fuel pump does not get started while you are working by a friend that wants to listen to music… that will be a mess and a horror story.




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