Replacing Fuel Pump In Onan 5500: Step-By-Step Guide

Changing the fuel pump on an Onan 5500 generator can be a challenging task. While some people choose to take their generator to a dealer or service centre for repairs, others prefer to replace the fuel pump themselves. In this discussion, we will explore the steps and challenges involved in changing the fuel pump on an Onan 5500 generator, including common issues such as fuel filter restrictions and fuel line problems. We will also discuss potential solutions, such as installing an inline filter and replacing the entire fuel supply line. By the end of this conversation, you should have a better understanding of how to tackle this maintenance task and improve the performance of your Onan 5500 generator.

Disconnecting the wires from the fuel pump

Firstly, locate the fuel pump and its wires. The fuel pump is usually found underneath the generator compartment. Before you begin, ensure you have the necessary tools, such as a wrench or screwdriver, and protective gear, including gloves and eye protection.

Once you have located the fuel pump, the next step is to carefully disconnect the wires. Start by examining the connectors for any signs of corrosion. If there is corrosion, you can apply WD-40 or a similar product to help loosen the connection. Be gentle during this process, as you don't want to accidentally rip the wires out of the connector.

Gently pull the wires apart, separating them from the fuel pump. Take note of the wiring configuration to ensure you can reconnect them properly later. It may be helpful to take photos or make notes of the wiring setup for reference.

After disconnecting the wires, carefully move them away from the fuel pump to give yourself more space to work. You may want to tie or secure the wires safely to the side to prevent any accidental reconnections or damage during the rest of the fuel pump replacement process.

At this point, the wires from the fuel pump should be successfully disconnected, and you can proceed with the rest of the fuel pump replacement process. Remember to take your time and work carefully to avoid any damage to the wires or other components.

By following these steps, you can safely and effectively disconnect the wires from the fuel pump on your Onan 5500 generator, making it easier to perform maintenance or replace the pump as needed.

Finding the fuel filter

To find the fuel filter on your Onan 5500 generator, you'll first need to locate the fuel pump, as the filter is positioned just before it. The fuel pump is likely located under the generator.

The fuel filter is a small component that plays a crucial role in ensuring that clean fuel is delivered to the engine. It captures dirt, debris, and contaminants from the fuel before it reaches the engine, preventing damage to the generator's vital components.

Onan 5500 generators have two fuel filters. The first is located just before the fuel pump, and the second is positioned under the carburetor. However, some users have reported that Cummins, the manufacturer of Onan generators, has replaced the second fuel filter with an adapter, as there is already a fuel filter upstream of the fuel pump. This adapter is part number A026E529, and it replaces the fuel filter at the carburetor.

The primary fuel filter, which is located before the fuel pump, is part number 0149-2341-01. This filter is still necessary and should be changed at normal service intervals or when the fuel filter needs to be replaced.

When sourcing replacement fuel filters, it's important to use the correct part number and ensure compatibility with your specific Onan 5500 generator model.

Replacing the fuel pump

Firstly, you will need to disconnect the wires from the fuel pump. If the wires are difficult to disconnect, there may be some corrosion in the connector. Try using WD-40 to help loosen the connection. Be careful not to rip the wire out of the connector.

Next, remove the two bolts and the fuel line. You may need to take your generator to a dealer to access the correct parts. If you are unable to find the stock pump, you can replace it with a low-pressure pump. There are also cheaper options available on Amazon, although be aware that these may be Chinese knock-offs.

When replacing the fuel pump, consider installing an inline filter in a location that is easy to access. This will help to prevent generator issues caused by fuel restrictions. You can also add a length of hose between the filter and the pump so that it can be placed in a more convenient spot.

Finally, ensure that you have the correct fuel line size for your generator. Different builders install different sizes of fuel lines, so it is important to check that you have the right one.

Choosing a replacement fuel pump

When choosing a replacement fuel pump for your Onan 5500 generator, there are several factors to consider. Firstly, you need to ensure that the replacement fuel pump is compatible with your specific generator model. In this case, you are looking for fuel pumps compatible with the Onan 5500 5.5KW Gas Generator.

Next, you should consider the type of fuel pump. The Onan 5500 generator typically uses a low-pressure 12V electric fuel pump. When searching for a replacement, look for one with similar specifications, such as a 12V electric fuel pump with a similar pressure rating.

Additionally, you should pay attention to the fuel pump's compatibility with your generator's fuel type. The Onan 5500 is a gas generator, so ensure that the replacement fuel pump is designed for use with gasoline.

Another important consideration is the quality and source of the replacement fuel pump. While you may be tempted to opt for cheaper options, it is essential to balance cost with reliability and durability. In some cases, opting for a more affordable fuel pump from a lesser-known brand may work just fine, as evidenced by some users' positive experiences with Amazon's E11015 fuel pump, which is a Chinese knockoff of the OEM pump. However, it is worth noting that some users have also expressed concerns about the longevity of these cheaper alternatives. Therefore, when choosing a replacement fuel pump, it is advisable to consider your budget and how often you are willing to replace the pump.

Lastly, always refer to the manufacturer's recommendations and specifications for the fuel pump. Consult your generator's user manual or seek advice from authorized dealers or mechanics to ensure you select a suitable replacement fuel pump that meets the required standards.

Troubleshooting fuel pump issues

Identifying the Issue:

• Check for unusual noises: One of the early signs of fuel pump issues is the absence of the familiar priming sound. If you don't hear the aggressive priming noise, it could indicate a problem with the fuel pump or a lack of power supply to the pump.
• Monitor generator performance: Observe how the generator runs. If it starts and then suddenly stops after a few minutes, it could suggest fuel pump issues or a clogged pre-filter.
• Inspect the fuel filter: Check the fuel filter after running the generator for a while. If it remains dry or doesn't fill up as expected, it could indicate a faulty fuel pump or a blockage in the fuel system.
• Test fuel pressure: Use a pressure gauge to test the fuel line pressure. If the pressure falls below the specified range (3-6 psi), it likely indicates a faulty fuel pump or a blockage in the fuel line.

Resolving the Issue:

• Replace the fuel pump: If you suspect the fuel pump has failed, consider replacing it with a suitable alternative, such as the Airtex E11015 Electric Fuel Pump, which is compatible with the Onan 5500 generator.
• Address fuel line issues: Check the rubber fuel line for cracks or stiffness, as these could lead to air suction issues. Replace the fuel line if necessary.
• Clean or replace the fuel filter: If the fuel filter is clogged, clean or replace it to ensure uninterrupted fuel flow.
• Adjust the float level: In some cases, the float level in the carburetor may need adjustment to regulate fuel flow and prevent flooding.
• Ensure proper levelling: Make sure your RV is level, especially front to back. A slight tilt can affect the fuel pump's performance due to the distance between the fuel tank and the generator.

Remember to consult a certified technician or refer to the service manual for detailed instructions on replacing the fuel pump and making specific adjustments to your Onan 5500 generator.

Frequently asked questions