Changing Fuel Filter: Onan Generator Maintenance Guide

Changing the fuel filter on an Onan generator is a necessary part of generator maintenance. While the process can be messy, it is a pretty easy DIY project. The fuel filter is easily accessible from underneath the RV. First, you need to remove the fuel line from the fuel filter. You will also need to plug or pinch off the fuel line to prevent gasoline from leaking out. After removing the rubber grommet from the oval hole, the fuel filter can be accessed. Using a deep well 9/16 socket, the old filter can be unscrewed from the fuel pump. It is important to be cautious when removing the old fuel filter, as it will be full of gasoline. Once the old filter is removed, you can install the new fuel filter. You should always start nuts by hand to avoid cross-threading. After tightening the nuts with a wrench, you can prime the fuel line and start the generator. It is important to check for fuel leaks once the generator is running.

Opening the fuel filter access panel

To open the fuel filter access panel, you'll need to locate the access panel under the generator. The panel is usually secured with two black indented latches. Squeeze these together and allow the door to swing downwards on its hinges. You should then be able to see the fuel filter, a small silver box, and the nut that secures it in place.

The access panel is located in a small recessed opening at the bottom of the generator, so it can be a tight space to work in. It's a good idea to have a drain pan in place to catch any fuel that might leak out, and to have some rags to hand to mop up any spills.

Before you begin, make sure you have the right replacement fuel filter for your generator model. For example, the Onan 7.5-kilowatt QuietDiesel generator uses the Cummins 1492513 Onan Fuel Filter, while the Onan 8kW diesel generator may use either part #149-2513 or #147-0860, depending on the model.

Once you've gathered your tools and the new filter, you can open the access panel and get started on changing the fuel filter.

Setting the drain pan and cleaning the area

To change the fuel filter on an Onan generator, you'll need to set up a drain pan and clean the area. Here's a step-by-step guide to help you through the process:

• Place a drain pan underneath the generator: Position a suitable drain pan directly below the generator to catch any fuel or oily debris that may drip during the filter replacement process.
• Clean the area: Use a clean rag or towel to wipe down the old fuel filter and the surrounding area. This will help prevent dirt or debris from entering the fuel system during the replacement process.
• Prepare for fuel spillage: Fuel will likely spill when you disconnect the fuel lines, so be prepared with rags or absorbent materials to catch the spillage. You can also wrap a rag around your wrist to catch any fuel that may run down your arm as you work. Remember to dispose of any fuel-soaked rags appropriately at an approved disposal or recycling centre.
• Disconnect the fuel lines: Before you begin, make sure you have the necessary tools, such as appropriately sized open-end wrenches, to loosen the nuts securing the fuel lines to the filter. Loosen the nuts one at a time, being careful not to cross-thread the fuel lines. Allow the fuel to drain into the oil pan until it stops dripping.

By following these steps, you will effectively set up the drain pan and clean the area before proceeding with the fuel filter replacement on your Onan generator.

Disconnecting the fuel lines

Before beginning, ensure you have the necessary tools, such as a set of open-end wrenches and a disposable rag. It is also important to place a drain pan underneath the generator to catch any dripping fuel.

To disconnect the fuel lines, follow these steps:

• Loosen the nuts securing the fuel lines into the filter: Use two appropriately-sized open-end wrenches to loosen the nuts. Be careful not to twist the fuel line and always use two wrenches to avoid this. It doesn't matter which fuel line you remove first, but be aware that some fuel will drip from the first line you disconnect.
• Drain the fuel: Once the first fuel line is disconnected, allow the fuel to drain into the oil pan until it is barely dripping. This may take a few minutes.
• Disconnect the second fuel line: There will be additional fuel dripping, so ensure the drain pan is still in place. Again, be cautious not to twist the fuel line and only use the wrenches on the nut.

PRO TIP: To prevent fuel from running down your arm, wrap an old rag around your wrist to catch the fuel. Diesel fuel is considered toxic waste, so try to avoid spilling it on yourself or the ground. Properly dispose of any fuel-soaked rags at an approved disposal or recycling centre.

Now that the fuel lines are disconnected, you can remove the old fuel filter and install the new one. Remember to always start the nuts by hand to avoid cross-threading.

Removing the fuel filter

To remove the fuel filter from your Onan generator, you'll first need to open the fuel filter access panel. This is located under the generator and can be opened by squeezing the two black indented latches together and letting the door swing downwards.

With the access panel open, you should now be able to see the fuel filter and the nut that secures it in place. Place a drain pan underneath to catch any fuel drips and use a rag to wipe the area clean.

Next, you'll need to disconnect the fuel lines. Using two appropriately-sized open-end wrenches, loosen the nuts that secure the fuel lines to the filter. It doesn't matter which line you remove first, but be aware that some fuel will drip from the first line as you disconnect it. Once you've disconnected the first line, allow the fuel to drain into your oil pan until it's barely dripping. Then, disconnect the second line.

Now, use your socket wrench to remove the nut at the centre of the fuel filter. Carefully remove the fuel filter, as it will still be full of fuel. Lower it into your drain pan, turning it face down so it can drain as much as possible.

Installing the new fuel filter

Now that you've disconnected the fuel lines and removed the old fuel filter, it's time to install the new one.

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. To avoid cross-threading, always start nuts by hand. 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.

Tighten the centre nut and use a rag to clean up any fuel drips. Leave the access panel open, as you'll need to check for leaks.

The new filter will be empty when it's first installed, so you'll need to re-prime the filter and fuel line. Do this by holding down the generator stop switch for one minute. You'll 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.

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