Onan Generator Runs Then Shuts Down?

Onan Generator Runs Then Shuts Down? 10 Possible Reasons & Help!

There’s a problem with your Onan generator runs then shuts down. After years of flawless operation, it suddenly stopped working. What may be a problem? Need assistance because you’re unsure. We’ll discuss the causes of your Onan generator shutting down and possible fixes.

The Generator Starts But Quickly Shuts Off – What Could Be The Problem? 

What should I do if my Onan generator keeps shutting down? There are several reasons, including:

  • An overheated engine
  • A motor or generator mechanical issue
  • A power output issue.

An Overheated Engine

Numerous issues may arise when an engine overheats. Your engine seizing is the worst-case situation. Because of the tremendous heat at this point, the piston rods become caught in the cylinder. When you leave the generator running, you should apply a fuel stabilizer to stop this from happening. Before starting it up, if it has been sitting for a while and your gas is more than 30 days old, switch to a new tank.

A Motor Or Generator Mechanical Issue

Another problem that might result in your generator shutting down is a mechanical fault with the motor or generator. Occasionally, a blocked fuel filter will prevent the engine from starting. It would help if you kept an eye on the generator while running to ensure there were no strange noises or vibrations. You should stop using anything that looks out of the norm and look into it more.

Additionally, make sure that all electrical connections are safe by checking them all.

A Power Output Issue

Another factor that might cause your generator to stop working is an issue with the power output. The generator automatically generates electricity and transfers it to the electrical appliances in your RV when you turn it on. If you observe one, you must determine whether a problem with the generator or an appliance exists.

Possible Causes Of An Onan Generator Shutting Off

Note that these are not promises. An expert specialist ought to inspect the generator.

Onan Generator Overheating

A clogged air filter may blame for this issue. Due to the high operating temperatures of the engine, the air filter clogs up with debris and oil, causing the engine to draw in too much air and shut off. If that’s the case, a new air filter must be installed.

Low Oil

For optimal lubrication and engine operation, Onan generators need a specific volume of oil. The engine may run hot and shut off if the generator’s oil supply runs short.

Loose Wire

The generator may experience several problems due to loose wiring. The most frequent problem is when a wire touches another metal surface, which shorts it out and causes the generator to overload and shut off.


Water may enter an alternator through a damaged gasket or any other tiny, unprotected opening in the system. Water is a conductor. Thus it will overload the generator and finally force it to shut off.

Faulty Spark Plug

A faulty spark plug can cause overheating (which might cause the engine to shut off) or a loss of power (making it difficult for the engine to run). Note: Depending on how you operate your generator, you may want to think about changing all of your spark plugs after 1,000 hours of use or more.

Bad Voltage Regulator

If the voltage regulator is sufficiently problematic, it may result in an undercharging problem, or it may cause the generator to overcharge and short out, leading to overheating and shutting down. A regulator works with an alternator to charge the battery.

Bad Generator Belt

If the belt on your Onan generator is damaged, it won’t be able to spin any of the associated parts, such as the alternator or water pump. If your Onan generator always starts with a screeching sound, the tension may need to be changed, or the belt may be broken.

A Defective Water Pump

A bad water pump might prevent adequate coolant from flowing through the system, causing the engine to overheat and eventually shut down. You should check to see if your water pump is in excellent operating condition if you find that your Onan generator overheats more frequently than usual.

Defective Alternator

If your Onan generator’s alternator is terrible, it won’t recharge the battery sufficiently, forcing it to operate at a reduced voltage and finally shut down. Reminder: If your Onan generator is operating too hot but not shutting off, your alternator could malfunction.

A Defective Regulator Or Rectifier

Your Onan generator may experience a multitude of issues as a result of a malfunctioning regulator or rectifier. The battery cannot charge properly if the regulator is broken since it won’t receive a constant supply of electricity from the generator. If the regulator/rectifier is inadequate, an overcharging issue that results in overheating could also arise (which can result in your Onan generator shutting down.

How To Troubleshoot Your Onan Generator That Runs Then shuts down

An Onan generator is equipment that most people don’t know is important until they need one. Many people use their generators to power certain appliances during blackouts or camping in their RV.

An Onan generator owner recently told us that it abruptly cut off after operating the same generator for years without any issues.

Many owners of Onan generators have had this issue. While most people know that all machines ultimately wear out and require replacement components, it may still be irritating when your generator suddenly stops down, especially if it has been working flawlessly for years. When your generator goes down, you can suffer any of the following symptoms:

  • Doing a specific task or using a certain appliance might trigger the shutdown
  • The generator runs for longer periods of time before shutting down
  • The generator runs for a shorter period of time before shutting down
  • The generator runs for a bit, then shuts down

How To Fix An Onan Generator That Runs Then Shuts Down

The good news is that you can check a few things to attempt to address this issue on your own.

  • Verify that the generator is receiving the appropriate amount of oil. Its operation may be impacted by too much or too little.
  • Ensure the air filter is clear and clean to prevent airflow to the generator.
  • Take some time to consider whether your use of the generator or the appliances has changed and if you have acquired any new equipment. Suppose the issue first appeared after carrying out a specific action. In that case, there may be a problem with the appliance or how you use it. Your generator may shut down under certain circumstances.
  • Even if everything previously worked, it should check for moisture inside and around the machine. Sometimes a piece of equipment could not operate properly, which might lead your Onan generator to shut down.
  • Even if everything previously worked, it should check for moisture inside and around the machine. Sometimes a piece of equipment could not operate properly, which might lead your Onan generator to shut down.
  • Replacement parts may be able to solve the issue if it is a control panel or even a cable.
  • A low oil shutdown is a safety mechanism that prevents the generator from running for an excessively long time and causing harm. However, suppose you have a lot of oil. In that case, your generator can occasionally be overheated and require some downtime to cool off.
  • Your Onan generator’s age and condition will determine whether changing the ignition module will work or not. It might be what you need to do to repair the issue if it appears after a specific task.

No matter the problem, if you have the right Onan parts on hand, you can get your generator back up and running. You might want to seek the assistance of a qualified Onan generator repair firm if you are unclear about what to do or if it appears too difficult.

Closing Notes

Onan generators can be durable and dependable tools, but they require maintenance. Your best strategy is to figure out the issue and take the appropriate actions if your generator keeps shutting down. Onan generators frequently have various issues, including electrical, fuel, and oil leakage. Your Onan generator might quit due to any one of these problems.

Related FAQs

How Does An Onan Generator Work?

An Onan generator generates electricity using a technique known as magnetohydrodynamics. As a rotor rotates through permanent magnets, it generates an electric current. A voltage regulator is then used to adjust the voltage to the correct level.

How Should My Onan Generator Be Maintained?

Regular maintenance will enable your generator to run as long as feasible. Considerations include performing routine oil changes, inspecting the air filter, and repairing parts as needed.

Is It Possible To Use An Onan Generator Like A Central A/C System?

Yes. Your Onan generator can function similarly to a central air conditioner. You must complete a few tasks first. This entails positioning it next to an outlet with sufficient power to support the generator’s load, covering it, and preparing the ducting so you can connect everything.

What Are The Features Of An Onan Generator?

An automotive-style engine, minimal oil shutdown, and simple access to services sites are all hallmarks of an Onan generator. In general, Onan generators cost more than comparable portable generators but are known for their dependability.

What Is The Onan Company?

In the 1920s, a company that would later be known as Onan began operating as a generator of electrical power. In the 1960s, they entered the portable generator industry and quickly rose to prominence. Club Car, a firm that makes golf carts, purchased the business.

How Often Should You Change The Oil In Your Onan Generator?

Every 40 hours, the oil needs to be changed. Every 50 hours, if it has been running for longer, the oil has to be changed. After changing your oil, properly dispose of the old oil.

How Much Are Onan Generators?

An Onan generator’s price varies according to its size and model.

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