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Onan Generator Carburetor Cleaning

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Cleaning Your Onan Generator Carburetor

Onan generator carburetor cleaning can be done with very few tools and a little patience. In this article, we’re diving into the world of DIY maintenance. Specifically, we’re going to tackle a task that every RV enthusiast should know how to do: cleaning the carburetor on your Onan generator. This should work for you whether you have an Onan 4000, Onan 5500 or Onan 6000.  So, buckle up, because this isn’t our typical travel blog!

“I have been working on small engines since I was a teenager. I tore apart mini bikes, lawn mowers, go-karts, snowmobiles and many other small engines and learned how to put them together again. It was this experience that has helped me repair many other small engines throughout my lifetime.”

Who makes the engines for Onan generators?

Currently, Onan-branded products are manufactured under the umbrella of Cummins Power Generation, a subsidiary of Cummins Inc.. Cummins is renowned globally for its expertise in designing and producing power generation solutions, especially diesel engines used in the transportation industry.

Cummins began the acquisition of Onan in 1986 and completed it in 1992.
Widely utilized in recreational vehicles, marine vessels, commercial mobile units, and residential standby systems, Onan-branded products stand as trusted choices across various applications.

We also have an Onan Generator video that goes into more detail, if that works better for you.

Onan Generator Revival on Youtube

Why Clean Your Onan Generator Carburetor?

Before we get our hands dirty, let’s understand why cleaning the carburetor is essential. Picture this: you’re out in the wild, relying on your trusty generator to keep things running smoothly. Suddenly, it starts acting up. What could be the culprit? Well, often, it’s old fuel gunking up the carburetor. Fuel sitting in the carburetor bowl can evaporate and leave behind residue, causing your generator to sputter or refuse to start altogether. That’s where cleaning comes in handy.

What Tools Will You Need?

Now, let’s talk tools. Unlike your typical mechanic shop, when you’re RVing, you have limited resources. So, here’s what you’ll need:

You should replace the fuel filter and air filter now and then and do an oil change at the interval specified by the manufacturer.

The Onan Generator Carburetor Cleaning Process

Alright, let’s get down to business. Here’s a step-by-step guide to cleaning your Onan generator’s carburetor:

  1. Preparation: Before diving in, ensure you have the necessary supplies ready. Carburetor cleaner is a must. If you don’t have any, a trip to the nearest auto parts store or Walmart might be necessary.
  2. Accessing the Carburetor: Start by removing the air cleaner cover and any other components obstructing access to the carburetor.
  3. Disassembly: Carefully detach the carburetor from the generator. Every generator and carburetor will be different, so if you have a service manual for your model, even better. Take note of any electrical connectors or hoses that need to be disconnected.
    • PRO TIP: If you’ve never done this before, take pictures as you go. This will allow you to put your Onan Generator carburetor back together and not have spare parts left over.
  4. Cleaning: Once the carburetor is removed, it’s time to clean it. Use the carburetor cleaner to remove any gunk or residue buildup. Pay special attention to the jets and valves, as these are common areas for blockages. A small set of pipe cleaner brushes is a huge help.
  5. Inspection: While cleaning, inspect all components for any signs of damage or wear. This is also a good time to check for loose connections or leaks.
  6. Reassembly: Once you have everything cleaned and inspected, carefully reassemble the carburetor, ensuring all parts are securely attached.
  7. Testing: With the carburetor back in place, fire that baby back up for a test run. Prime the carburetor if necessary and observe its performance. Ideally, your generator should start smoothly and run without any issues.
onan generator onan 5500 carburetor cleaning

Onan Generator | Onan 5500 Carburetor Cleaning

What is the life expectancy of an Onan generator?

If you properly maintain your Onan generator by doing regular oil and air filter changes, you can expect to get 10-15 years or more out of it. The one on our rig was manufactured around 2006 and is still going.

How often do you change the oil in an Onan generator?

The Onan generator manual (if you read those kinds of things), suggests oil changes either annually or after every 100 hours of operation. An oil change is pretty straightforward, requiring less than an hour to complete. If you’ve ever changed oil in a car or lawn mower, you’ll find the process familiar. Ensure you have the necessary tools and materials on hand before beginning. We have some of the materials listed above.

A Note of Caution While Working on Your Onan Generator

Throughout the process, remember to work methodically and safely. Take your time, especially when handling delicate components like jets and valves. And if you’re ever unsure about a step, don’t hesitate to seek professional assistance.

And by “professional” I mean, NOT ME!


There you have it, folks – a crash course in cleaning your Onan generator’s carburetor. While it may seem daunting at first, with a bit of patience and the right tools, it’s a task any RV enthusiast can tackle. So, the next time your generator starts acting up, don’t panic – roll up your sleeves and give it some TLC. Happy RVing!

And by the way, this works on most small engine carburetors, including mini bikes, atvs, side by sides and most other things with carburetors.

If you’re curious about what is going on with us lately, check out this post, living in Los Barriles California Sur and loving it.

Disclaimer: The information provided in this blog post is for educational purposes only. Always exercise caution and consult a professional if you’re unsure about performing maintenance tasks on your generator.

You can get more technical information on your Onan generator at Cummins RV Generators.

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