Changing The Fuel Filter On An Onan 4000: Step-By-Step Guide

The Onan 4000 fuel filter can be replaced by first removing the fuel line from the filter, which then needs to be plugged or clamped to prevent fuel leakage. The rubber grommet can then be removed, revealing the fuel filter. Using a deep socket, the old filter can be unscrewed from the fuel pump and replaced with a new one. The new fuel filter should be tightened by hand to ensure the threads are straight and not crossed, and then a socket can be used to fully tighten it.

The fuel filter is easily accessible from underneath the RV

The fuel filter on a Cummins Onan RV Generator is easily accessible from underneath the RV. The first step is to remove the fuel line from the fuel filter. It is important to plug or pinch off the fuel line to prevent the leakage of gasoline due to gravity. A rubber grommet can be removed from the oval hole, revealing the fuel filter. A deep well 9/16" socket can be used to turn the fuel filter counterclockwise to unscrew it from the fuel pump. It is important to be cautious as the fuel filter contains gasoline.

Once the old fuel filter is removed, a small amount of Permatex High-Temperature Thread Sealant can be applied to the base of the threads on the new fuel filter. The new fuel filter is then connected to the fuel pump by fitting it inside the oval hole. It is important to take your time and ensure that the threads go on straight and are not crossed. After getting the fuel filter started, it can be tightened with a socket, being careful not to overtighten. Finally, the rubber grommet and fuel line can be replaced. The entire process takes under fifteen minutes and ensures the generator runs smoothly.

Remove the fuel line from the fuel filter

To remove the fuel line from the fuel filter of an Onan 4000 generator, you must first plug or pinch off the fuel line to prevent leakage. You can do this by using a piece of dowel to plug the line, or by clamping or pinching it with a pair of channel locks. This is important because, as gravity will cause the fuel line to leak gasoline, you want to protect your eyes and face from potential splashes.

Once the fuel line is secure, you can then remove the rubber grommet from the oval hole, revealing the fuel filter. You can then use a deep well 9/16" socket to turn the fuel filter counterclockwise and unscrew it from the fuel pump. Be careful, as the fuel filter will be full of gasoline.

If you are having trouble accessing the fuel filter, it may be because it is screwed into the suction port on the pump and is only accessible from the side of the generator base.

Use a rubber grommet to reveal the fuel filter

To reveal the fuel filter on an Onan 4000, you will need to remove a rubber grommet from an oval hole. This is a relatively straightforward process, but it is important to be cautious as the fuel filter will be full of gasoline.

First, remove the fuel line from the fuel filter. It is important to plug or pinch off the fuel line, as gravity will otherwise cause the fuel line to leak gasoline. The rubber grommet can then be removed from the oval hole, revealing the fuel filter.

A deep well 9/16" socket will fit perfectly on the end of the fuel filter. Slowly turn the socket counterclockwise to unscrew the old filter from the fuel pump. Be sure to exercise caution, as the filter will be full of gasoline.

Once the old filter has been removed, you can begin to install the new fuel filter. Apply a small amount of Permatex High-Temperature Thread Sealant to the base of the threads on the new fuel filter. The new fuel filter will fit inside the oval hole and can be connected to the fuel pump. Take your time with this step, ensuring that the threads go on straight and are not crossed.

After getting the fuel filter started, tighten it with a socket. There is no need to overtighten, just ensure that it is firmly in place. Finally, replace the rubber grommet and fuel line.

Use a 9/16 socket to remove the old filter

To remove the old fuel filter from your Onan 4000 generator, you'll need a 9/16 socket. This deep well or deep socket will fit perfectly on the end of the fuel filter.

Before you begin, make sure you have plugged or pinched off the fuel line to prevent fuel from leaking out. You can use a piece of dowel to do this.

Now, with your 9/16 socket, slowly turn the fuel filter counter-clockwise. It will start to unscrew from the fuel pump. Be careful as the filter is full of gasoline, so protect your eyes.

Take your time with this process and be careful not to overtighten any connections as you remove the old filter.

Apply Permatex High-Temperature Thread Sealant to the new fuel filter

To apply Permatex High-Temperature Thread Sealant to the new fuel filter of your Onan 4000, follow these steps:

Firstly, ensure you have cleaned and dried the parts that you will be applying the sealant to. The Permatex website recommends using their Permatex Surface Prep activator for this.

Secondly, knead the tube of Permatex High-Temperature Thread Sealant before use. This ensures that the sealant is properly mixed and ready to be applied.

Thirdly, apply the sealant to the leading threads of the male fitting, leaving the first thread free of sealant. You only need to apply the sealant to about 3/4 of a thread turn, it is not necessary to cover all threads.

Finally, assemble the parts and tighten them to the recommended torque.

Note that Permatex Thread Sealant is designed for use with threaded metal fittings on hydraulic, pneumatic, fuel, and cooling systems. It is not suitable for use with plastics or rubber. Always refer to the Technical Data Sheet for complete information.

Some additional tips from users who have replaced the fuel filter on an Onan 4000:

• Use a deep socket to remove and install the fuel filter
• Plug or pinch off the fuel line to prevent leakage
• Be careful not to cross-thread when installing the new fuel filter
• Check for leaks after installation
• Do not overtighten the fuel filter

Frequently asked questions