Master the Art of Onan Generator Repair!

Table of Contents

1. Introduction
2. Understanding Generators and Diesel Engines
   • Components of a Mechanical Generator
   • Fuel Solenoid Functionality
   • The Role of Glow Plugs
3. Common Issues with Starting Generators
   • Difficulty Starting
   • Need for Glow Plugs
   • Troubleshooting Starting Issues
4. Replacing Glow Plugs in Generators
   • Checking Glow Plug Length
   • Testing Glow Plug Functionality
   • Purchasing Quality Glow Plugs
   • Steps to Replace Glow Plugs
5. Additional Tips for Generator Maintenance
   • Cleaning the Radiator
   • Ensuring Fuel Flow
   • Preheating the Engine
6. Conclusion

Understanding Generators and Diesel Engines

Generators can be a reliable source of backup power, but they can sometimes be challenging to start, especially if you are unfamiliar with diesel engines. In this article, we will explore the different components of a mechanical-style generator and discuss the role of glow plugs in the starting process.

Components of a Mechanical Generator

Mechanical-style generators, particularly older models, consist of relatively simple components. One crucial part is the fuel solenoid, responsible for controlling the flow of fuel to the engine. When you want the generator to start, the solenoid moves in one direction, allowing fuel to enter the engine. Conversely, when you want the generator to stop, the solenoid moves in the other direction, cutting off the fuel supply. Fundamentally, there is usually only one wire connecting the solenoid, the plus wire, and the starter, making the system straightforward.

Fuel Solenoid Functionality

The fuel solenoid's primary function is to ensure the generator's engine starts and keeps running as long as it is fueled and turning over. However, these mechanical-style generators can sometimes experience difficulty starting, especially the smaller ones equipped with less sophisticated fuel pumps. When starting becomes more challenging, it may be an indication that glow plugs are needed to aid the starting process.

The Role of Glow Plugs

Glow plugs play a vital role in starting diesel engines, particularly in cold weather or when the engine is struggling. By providing additional heat, glow plugs help ignite the fuel-air mixture in the combustion chamber, facilitating the starting process. If your generator is having trouble starting, testing the glow plugs can help determine if they are functioning correctly.

Common Issues with Starting Generators

Starting issues are common in generators, particularly as they age. Understanding the reasons behind these problems can empower you to troubleshoot them effectively. Let's explore some common issues with starting generators and how glow plugs can solve them.

Difficulty Starting

One primary indication of a starting problem is when your generator becomes increasingly hard to start. This can be particularly pronounced in smaller generators equipped with less sophisticated fuel pumps. If you find yourself having to make multiple attempts to start the generator before it finally starts, it's time to consider the role of glow plugs.

Need for Glow Plugs

Generators, especially diesel engines, benefit from glow plugs when starting becomes challenging. Glow plugs provide additional heat to the combustion chamber, aiding in the ignition of the fuel-air mixture. Using glow plugs in your generator can improve its starting performance and overall reliability.

Troubleshooting Starting Issues

If your generator is having trouble starting, a simple troubleshooting process can help identify the root cause. Start by engaging the starter button and observing the fuel solenoid's movement. The solenoid should respond by moving in the correct direction and causing the engine to turn over. If the engine does not start, try loosening the injector to check if fuel squirts out. If not, the problem may lie in the fuel filter or lift pump.

Replacing Glow Plugs in Generators

Replacing faulty glow plugs is a straightforward process that can significantly improve your generator's starting performance. Follow these steps to ensure a successful replacement.

Checking Glow Plug Length

Before purchasing new glow plugs, it is essential to check the length of the existing ones. The distance from where the glow plug seats inside the cylinder head to the tip should be roughly the same for optimal functionality. This measurement ensures a proper fit and reliable heat transfer.

Testing Glow Plug Functionality

To test if a glow plug is functioning correctly, use an old meter set to a relatively low resistance setting (200 to 500 ohms). Connect one end of the meter to the glow plug's end and the other end to the glow plug's connecting wire. A healthy glow plug should register around 100 ohms. If the resistance is significantly higher or lower, the glow plug may be faulty.

Purchasing Quality Glow Plugs

When shopping for replacement glow plugs, it is advisable to avoid buying them directly from the generator manufacturer, as they can be costly. Instead, opt for reputable brands like Bosch. These aftermarket glow plugs offer the same quality at a fraction of the price. You can often find suitable replacements online at a more affordable price.

Steps to Replace Glow Plugs

The process of replacing glow plugs in generators is relatively simple and can be completed in about 10 to 15 minutes. Start by disconnecting the wire from the glow plug, then remove the old glow plug using a 12 mm wrench or socket. Replace it with the new glow plug, ensuring a secure fit. Repeat the process for all the glow plugs that require replacement.

Additional Tips for Generator Maintenance

While replacing glow plugs can significantly improve your generator's starting performance, regular maintenance can prolong its lifespan and enhance its reliability. Consider the following tips for generator maintenance:

Cleaning the Radiator

It is crucial to keep the radiator clean to ensure optimal airflow and cooling. Avoid debris buildup that can impede the generator's performance by periodically cleaning the radiator. Using a degreaser or gunk remover, spray the radiator and wash it thoroughly to clear any dirt or grime.

Ensuring Fuel Flow

Regularly check the fuel filter and lift pump to ensure proper fuel flow to the generator's engine. Any blockages or malfunctions in these components can hinder starting and overall performance. If you notice fuel-related issues, inspect the fuel filter and lift pump for any signs of malfunction.

Preheating the Engine

To facilitate smoother starts, especially in colder conditions, preheating the engine is beneficial. Ensure the glow plugs are functioning correctly, and engage them for a few seconds before attempting to start the generator. This extra heat can provide the necessary ignition boost during the starting process.

Conclusion

Starting a generator should not be a daunting task, particularly when armed with a basic understanding of its components and troubleshooting techniques. By comprehending the role of glow plugs and ensuring their functionality, you can overcome starting difficulties and improve your generator's overall performance. Remember, regular maintenance, such as cleaning the radiator and checking fuel flow, is essential for optimal generator operation. By following these guidelines, you can enjoy a reliable and efficient backup power supply for years to come.