In addition to being quiet and efficient, Onan 5500 generators are also compact. However, when it doesn’t start, what could be causing the problem and how you resolve it are important questions to ask. We’ve researched to make it easier for you to get your generator up and running again. You should try to prime the Onan 5500 generator if it doesn’t start the first time.
If the engine does not start when the button is turned, you either have a battery issue or a problem with the starter or solenoid, which are very expensive to replace. The symptoms of a hard start combined with a large amount of white smoke may suggest a problem with the injectors or fuel flow.
Your generator must be ready to go whenever you need it, no matter what you use it. This article will cover our investigation into the reasons for your Onan 5500 generator’s inability to start. We will also discuss and provide answers to other frequently asked questions, so please continue reading.
How do I reset my Onan 5500 generator?

The Onan 5500 generator should be reset if it is experiencing difficulties. Follow these simple procedures to accomplish this:
Step 1; To begin, locate the priming button on the generator’s control panel and press it (mainly on the side of the generator).
Step 2; After that, press and hold the priming key for at least 30 seconds before letting off the trigger.
Step 3; Turn on the generator and allow it to operate for 15 minutes before shutting it down.
Step 4; As a result, any active codes should be cleared.
Step 5; Repeat these instructions if the codes are not clear.
If, after multiple attempts, it cannot reset the codes, then consult your local Onan dealer for assistance.
How do I test my Onan generator solenoid?

Solid-state relays (solenoids) are found in all electrical equipment, ranging from electronic door locks to complicated machinery. They are made of tiny wires coiled around together, and when current is given to them, magnetic fields are generated, which are used to operate valves and switches.
How to test an Onan generator solenoid | Functions | Essential products |
Check the battery | To check for enough power provision | Check the multimeter from Amazon |
Check the voltage | To know where the problem is | Multimeter |
Check whether the solenoid is damaged | To check for an issue inside the solenoid | Voltmeter |
1. Check the battery
Check your car’s battery; it’s possible that the battery isn’t charged enough to provide enough power. So, before you proceed, take out your multimeter and run a test to ascertain the battery’s voltage before continuing. You must attach the multimeter’s probes to the battery terminals by connecting the multimeter’s red probe to the battery’s positive terminal and the black probe to the negative terminal of the storm.
When you install them in this order, the battery should read roughly 12 volts if everything is working correctly; if it does not, there is a good chance that it is causing the solenoid to malfunction and that it will need to be recharged.
To know the multimeter I use, check the multimeter from Amazon.
2. Check the voltage
Now that you have determined that your car battery is operational, the following step determines how much voltage your battery is giving to the solenoid. Knowing the amount of voltage would assist you in determining whether the problem is with the interconnection between the solenoid and your battery.
Once again, take out your multimeter and attach the positive probe, represented by the red wire, to the positive electrode of the battery’s negative terminal. Plug the negative sensor from the multimeter to the ground terminal to complete the circuit. To determine which battery terminals are joyous, look for a “+” label or “POS” on them.
Make sure that your multimeter is set to volts and that you check the reading on your multimeter. It may flicker for a while, but wait until it settles. The multimeter must read approximately 12volts; if it reads less, your battery’s voltage supply is limited, and you should consider charging it.
Check the multimeter from Amazon.
3. Check whether the solenoid is damaged.
To test your solenoid for damage, connect the red probe of the voltmeter to the opposing end and the black probe to the positive terminal. Remember that the solenoid has two terminals, one of which is directly connected to the positive terminal of the automobile battery.
The solenoid’s negative terminal connects to the battery, while the positive terminal connects to the starter. If the voltage reading on the multimeter drops fewer than 0.5 volts, there is an issue inside your solenoid. However, if the solenoid is not detecting any voltage, then the solenoid is faulty and must be changed.
Check the voltmeter from Amazon.
How is an Onan 5500 generator primed?
Keep pressing and holding the prime button on the Onan 5500 generator for 30 seconds to prime it. The fuel pump will usually stop ticking when the carburetor float-bowl is complete with fuel. It will be possible to resume your generator after this has occurred.
Reasons an Onan generator will not start over

- Problem with the fuel valve
If your fuel valve is malfunctioning, fuel will not be able to flow into the carburetor. This indicates that the engine will not be able to start as well. Ensure that you inspect it and change it as necessary. This can be accomplished by dismantling and cleaning the item and visually evaluating it for damage. It should be reassembled if there is no damage and replaced if necessary.
Check the fuel valve from Amazon.
- A clogged carburetor
The carburetor will become blocked, and the generator will be unable to start. Cleaning your carburetor is as simple as shutting off the fuel valve and detaching the basin at the bottom. Additionally, you can try using an air compressor to blow off any debris obstructing the fuel flow path.
- Spark plugs are not working correctly.
If the spark plugs are faulty, they will be unable to supply the electrical charge required for starting the vehicle. By removing the spark plugs and inspecting them for damage or burns, you can determine if they are wrong. If they have been burnt, you need to replace them as soon as possible.
- Faulty oil sensor
If your oil sensor fails, it may result in an excessive amount of oil being pumped into the engine, preventing it from starting. Remember to check the oil level in your generator regularly. If the amount is excessive, it should be drained.
Check the oil sensor from Amazon.
- Dead battery
Failure to start the generator or the inability to keep the generator running are all examples of problems arising from a flat battery. If you want to avoid this, you should check your battery’s level and charge it if necessary. Any cracks should be repaired or replaced as soon as possible.
- A clogged filter
If the fuel filter is clogged with sediment, this will result in your generator failing to operate for a few minutes. The old fuel filter can be easily removed and replaced with a new one, which allows for a quick check.
- A damaged ignition coil
When the ignition coil fires, it ignites the fuel mixture in the engine, allowing it to begin running. Your generator may not be able to start if this component is malfunctioning. Make sure to regularly inspect it, ensure that it is not destroyed, and replace it if required.
- A bad recoil starter
Having a faulty recoil starter will prevent your generator from starting because you will be unable to pull the starter hard enough to ignite the fuel. As a result, you should inspect the starter for signs of damage and replace it if necessary.
- A faulty safety switch
Your generator can’t start if the safety switch has been tripped. The switch can be tested by first turning it on and then disconnecting both of its wires, resulting in an immediate shutdown of the engine. If there is no improvement, it should be replaced.
- Bad flywheel key
Your generator can’t start if the flywheel key is faulty. In this section, the pulley is housed, responsible for controlling the ignition timing. Immediately replace it with a new one if it is not present to ensure proper operation.
- A faulty voltage regulator
The voltage regulator ensures that the generator’s output is consistent. As a result of the low voltage levels, you will not be able to maintain your generator operating if it is malfunctioning, which may cause damage to internal parts such as brushes. Because of this, you should inspect it to ensure that it is not destroyed and replace it as necessary.
- Possible fuel leak
The generator will not run properly if there is a fuel leak because too much fuel will be forced into the engine. As a result, you should check for leaks and, if necessary, replace them.
Final verdict
We recommend that you maintain a safe distance between yourself and the vehicle if you must perform any of these tests. You should wear protective eyewear and keep a safe space between yourself and the car
Like any other mechanical machine, generators will experience troubles from time to time. The parts listed in this article should be checked if the Onan 5500 engine is not starting correctly. If you cannot resolve the issue on your own, you should seek assistance from an Onan dealer.