Changing Fuel Filters: A Step-By-Step Guide For Generators

Changing the fuel filter on your generator is an important part of generator maintenance. Fuel filters are designed to strain the gas before it reaches the carburetor, and replacing them can help prevent foreign particles from clogging your engine's fuel system. This guide will explain how to change the fuel filter on an Onan diesel generator, but the process is similar for other types of generators as well.

Finding the fuel filter

Locating the fuel filter in your generator is the first step to changing it. The fuel filter will either be inside the fuel tank or fitted into the fuel line between the tank and the fuel pump. Some fuel tanks have internal, non-serviceable fuel filters.

If you are unsure where your fuel filter is located, refer to your engine operator's manual to determine the location. If you own a Briggs & Stratton engine, the manual will specify the location of the fuel filter. If you do not have access to the manual, you may need to start where the fuel line attaches to the main tank and trace it until you find the filter.

Once you have located the fuel filter, you can proceed to remove and replace it. If the filter is installed inside the tank, you will need to drain the tank before removing the filter. If the filter is installed in the fuel line, simply remove the metal clips on each side of the filter using needle-nose pliers and slide the filter out.

Draining the tank

To drain the tank of your generator, you will need to locate the fuel valve and ensure it is in the OFF position. This will stop the flow of fuel to the carburetor. Typically, the fuel valve is located at the base of the fuel tank, where the gas line is attached. If your generator does not have a fuel valve, you can clamp the gas line using a fuel line clamp. It is important not to pinch the fuel line as this could cause damage.

Once the fuel flow is stopped, you can proceed to drain the fuel from the tank. Place a drain pan or oil pan underneath the fuel tank to collect the drained fuel. Some fuel will drip and continue to drain from the fuel lines for a short time, so ensure your drain pan is in place to catch any spills. Keep in mind that diesel fuel is considered toxic waste, so it is important to avoid getting it on yourself or the ground. Properly dispose of any drained fuel, used filters, and fuel-soaked rags at an approved disposal or recycling center.

Before draining the fuel, it is recommended to clean the area around the fuel filter using a rag. This will help to prevent any debris or contaminants from entering the fuel system during the draining process. Additionally, it is crucial to wear safety gear, such as eye protection, to protect yourself from liquid fuel or fuel vapors.

Now, you are ready to begin draining the fuel tank. Loosen the nuts or metal clips securing the fuel lines into the filter using the appropriate tools, such as open-end wrenches or needle-nose pliers. Be aware that fuel will start to drip from the fuel lines as you disconnect them. Allow the fuel to drain into your drain pan until it is barely dripping. Repeat this process for each fuel line connected to the filter.

After draining the fuel, carefully remove the fuel filter as it will still be full of fuel. Lower the fuel filter into the drain pan, turning it face down to allow for complete drainage. Keep the drain pan in place to catch any remaining fuel that may continue to drain from the fuel lines.

Disconnecting the fuel lines

Firstly, locate the fuel filter access panel. This is usually found under the generator, and you can open it by squeezing together the two black indented latches, allowing the door to swing downward on its hinges. Once opened, you will see the fuel filter, which is typically a small silver box, along with a nut that secures it in place.

Before disconnecting the fuel lines, it is important to set up a drain pan to catch any dripping fuel. Place the pan underneath the fuel filter to collect any spills. It is also recommended to have a disposable or expendable rag handy to wipe away any fuel spills or residue.

Now, you can begin to disconnect the fuel lines. Using two appropriately-sized open-end wrenches, loosen the nuts that secure the fuel lines to the filter. Be cautious, as some fuel will drip from the lines as you disconnect them. Once the first line is disconnected, allow the fuel to drain into your oil pan until it slows to a drip. Then, move on to the second fuel line. There will be additional fuel dripping, so ensure your drain pan is in place to catch it.

To prevent fuel from running down your arm, a useful tip is to wrap an old rag around your wrist to absorb the fuel. Remember that diesel fuel is considered toxic waste, so try to avoid getting it on yourself or the ground. Properly dispose of any fuel-soaked rags and waste at an approved disposal or recycling centre.

After both fuel lines have been disconnected, carefully remove the fuel filter, as it will still be full of fuel. Lower it into the drain pan, turning it face down to drain as much fuel as possible. Keep the drain pan in place, as fuel will continue to drain from the lines for a short time.

Finally, before installing the new fuel filter, ensure you clean up any fuel spills or residue with your rag. It is important to work in a well-ventilated area and wear protective gear, including safety eyewear, to protect yourself from fuel vapours and spills.

Removing the fuel filter

To remove the fuel filter from your generator, you will first need to locate it. The fuel filter will either be inside the fuel tank or fitted into the fuel line between the tank and the fuel pump.

If your fuel filter is inside the tank, you will need to drain the tank before attempting to remove the filter. Start by shutting the fuel valve, which is usually located at the base of the fuel tank, where the gas line is attached. If your tank does not have a valve, you can clamp the gas line using a fuel line clamp.

If your filter is installed in the fuel line, you can simply remove the metal clips on each side of the filter using needle-nose pliers and then slide the filter out.

Once you have located and accessed the fuel filter, you will need to use a socket wrench to remove the nut at the centre of the fuel filter. Be careful when removing the fuel filter, as it will still be full of fuel. Lower the fuel filter into a drain pan, turning it face down to allow it to drain. Keep the drain pan in place, as fuel will continue to drain from the fuel lines for a short time.

Installing the new fuel filter

To install the new fuel filter, first, hold the new fuel filter in place and finger-tighten both of the fuel line nuts as well as the nut in the centre. Always start nuts by hand to avoid cross-threading. Then, use your open-end wrenches to secure the fuel line nuts, tightening them one more flat (1/6 of a turn) after they’re seated against the fitting.

Next, tighten the centre nut and use your rag to clean up any fuel drips. Leave the access panel open, as you will need to check for leaks. The new filter will have no fuel in it when it’s first installed, so you will need to re-prime the filter and fuel line. Do this by holding down the generator stop switch for one minute. You will hear the clicking sound of the fuel pump running as the system re-primes.

Now, start the generator. If it doesn’t fire up after several seconds, you may need to prime the system a second time by holding down the stop switch again. Once the generator is running, look underneath and check for fuel leaks. Carefully check both fuel connections for dripping. If you see any drips coming out of either connection, shut down the generator immediately and re-torque the nut.

Let the generator idle to warm up, then turn on two or three high-power items in your RV, such as the air conditioner(s) and water heater (on electric, not propane). This will put a load on the generator, ramping up the RPMs. Allow the generator to run for 5-10 minutes under load while you continue to check for any fuel leaks. Again, any fuel leak, even a single drip, requires checking and re-torquing the fuel line nut(s) on the filter as needed.

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