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How to Troubleshoot Onan Generator Starter Problems

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Have you been trying to start your Onan generator, but it’s not starting? You have tried diagnosing the issue but cannot find the actual cause.

Onan generator starter problems refer to issues that prevent the starter from effectively initiating the engine’s rotation, leading to difficulties in starting the generator. 

Onan generator starter problems are mostly caused by weak or faulty batteries, problems with the starter motor, faulty solenoids, ignition switch issues, fuel and oil system complications, wiring and connection troubles, as well as mechanical obstructions within the engine.

Hence, in this blog post, we’ll explain further the causes of the Onan generators not starting, leading to starter problems, and the best way you can troubleshoot these problems.

Causes of Onan Generator Starter Problems 

For further explanation and understanding of why Onan generators develop starting problems, here are the common causes: 

Firstly, in most cases, a weak or faulty battery is one of the primary causes of starter problems. Whenever the battery doesn’t have enough charge or is unable to hold a charge, it may not provide sufficient power to engage the starter motor and turn the engine over.

Secondly, the starter motor itself can encounter problems over time. It may suffer from wear and tear, loose connections, or internal damage. A damaged or malfunctioning starter motor will struggle to initiate the generator engine’s rotation, leading to starting difficulties.

Thirdly, the solenoid is responsible for engaging the starter motor when you turn the ignition switch. If the solenoid is defective, it may fail to send the necessary electrical signals to the starter motor, which would prevent it from engaging or disengaging correctly.

During the generator starting process, the ignition switch plays the most important role. And if the ignition switch is faulty or damaged, it may not transmit the electrical signal to engage the starter motor. This can therefore result in a non-responsive or erratic starting behavior of the generator.

If there’s any problem within the fuel and oil system, such as the oil filter, or if there’s low oil pressure, it can also impact the starter’s performance. Insufficient fuel and engine oil supply, clogged fuel lines, or a malfunctioning fuel pump and oil filter can prevent the engine from receiving the necessary fuel for ignition, leading to starting problems. And at the same time trigger the oil pressure sensor, causing the generator to develop a starting problem.

When there are loose or corroded wiring connections, damaged cables, or faulty grounds, it can disrupt the flow of electrical current to the starter motor. These issues mostly inhibit the starter’s operation and cause starting difficulties for the generator.

Lastly, sometimes physical obstructions or mechanical problems within the engine can also hinder the starter’s operation. Issues like a seized or jammed engine, a damaged flywheel, or broken teeth on the starter gear can prevent the starter motor from engaging properly.

How to Troubleshoot Onan Generator Starter Problems

Step 1: Check the Battery

The first step in troubleshooting Onan generator starter problems is to inspect the battery. Start by ensuring it is adequately charged. 

Check the connections to ensure they are secure and free from corrosion. If the battery is old or unable to hold a charge effectively, it may be necessary to replace it with a new one to restore proper functionality and ensure the starter receives sufficient power to turn the engine over.

Step 2: Examine the Starter Motor

After checking the battery, the next step in troubleshooting Onan generator starter problems is to examine the starter motor. 

Carefully inspect the starter motor for any visible signs of damage or wear, such as cracks, broken parts, or excessive corrosion. Additionally, check the connections attached to the starter motor to ensure they are secure and free from corrosion.

If you notice any corrosion on the connections, clean them thoroughly to improve conductivity. Tighten any loose connections to ensure a reliable electrical connection.

However, if you observe significant damage to the starter motor or it is not functioning correctly despite the battery being in good condition, it may be necessary to have the starter motor repaired or replaced. 

Step 3: Check The Oil Level and Oil Filter

Sometimes, when there’s a low oil level on the generator or the oil filter is clogged, it might cause the generator to develop a starting problem.

And to fix this, you will need to check if the oil is low by using the dipstick on the oil side. I hope you know how to use the dipstick on RV Onan generators to know if there’s oil or not. 

To use the dipstick, first remove it by pulling it straight out from the oil filler tube, then wipe off any oil residue from the dipstick using a clean cloth or paper towel.

After that, reinsert the dipstick back into the oil filler tube, making sure it is fully seated, and push it down firmly but gently.

After you are done, withdraw the dipstick again and hold it horizontally. Check the oil level indicated on the dipstick. The dipstick usually has markings or indicators that show the minimum and maximum oil levels.

Ideally, the oil level should be between the minimum and maximum marks. If the oil level is below the minimum mark, you’ll need to add oil. If it’s above the maximum mark, you may need to drain some oil.

If the oil level is low, remove the oil filler cap on the generator and add the recommended type and amount of oil. After adding or adjusting the oil level, reinsert the dipstick back into the oil filler tube and make sure it is secured in place.

After you are done checking the oil level, also check the oil filter to see if it’s working efficiently. But if you think it’s something you can’t do, invite your technician to help you diagnose and troubleshoot it. 

Step 4: Test the Solenoid

To further troubleshoot Onan generator starter problems, it’s important to test the solenoid. The solenoid is responsible for engaging the starter motor when you activate the ignition switch. To test the solenoid, you can use a multimeter. Follow these steps:

  1. Ensure the generator is turned off and disconnected from any power source.
  2. Locate the solenoid, typically found near the starter motor.
  3. Disconnect the wires attached to the solenoid terminals.
  4. Set the multimeter to continuity or resistance mode.
  5. Place the multimeter probes on the solenoid terminals.
  6. Activate the ignition switch or have someone else do it while you observe the multimeter reading.
  7. The multimeter should indicate continuity or low resistance when the ignition switch is turned on. This confirms that the solenoid is receiving power and functioning properly.
  8. However, if the multimeter reading shows no continuity or high resistance, it indicates a defective solenoid that needs to be replaced.

After following the steps here, if the solenoid is indeed faulty, it is recommended you replace it with a new one, ensuring reliable engagement and disengagement of the starter motor during the starting process. 

Step 5: Fuel System Examination

If you have checked the starter solenoid, to further troubleshoot Onan generator starter problems, you should examine the fuel system.

To examine the fuel system, ensure that there is an adequate fuel supply reaching the engine. Make sure the generator has enough fuel in the tank. If the fuel level is low, refill it with the appropriate fuel.

Then examine the fuel lines for any blockages or restrictions that may impede fuel flow. Look for signs of damage or leaks in the fuel lines. If you find any blockages, remove them, and if there are leaks or damaged sections, replace the affected fuel lines.

After that, check if the fuel pump is functioning correctly. You can hear the sound of the fuel pump running when you activate the ignition switch. If you don’t hear any noise, it may indicate a malfunctioning fuel pump that needs to be repaired or replaced. This can also apply to the generator engine oil filter. 

And if you later identify any problems with the fuel system, such as blockages, leaks, or a faulty fuel pump, it’s essential to address them promptly. Clear any blockages, repair or replace damaged fuel lines, and have a professional technician inspect and repair the fuel pump if necessary.

This video would help you better.

Seek Professional Assistance

If you have watched the video and followed the troubleshooting steps and are still unable to resolve the Onan generator starter problem, it is advisable to seek professional assistance. 

Remember, safety is paramount throughout the troubleshooting process, and seeking professional assistance is a viable option if needed. 

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