bison logo

How to fix a generator spark plug

Learn the best way to repair your generator spark plugs. Learn the steps from checking for faulty spark plugs to repairing your generator spark plugs.

Table of Contents

Sometimes, failing generator spark plugs can be so frustrating that you might wonder what prompted you to purchase one.

In this case, you’ve probably tried everything possible, and you don’t know if the plug is the problem.

So, to save yourself the stress, in this article, China BISON will show you how to fix a generator spark plug.

Not only will BISON show you how to fix it yourself, but we’ll also show you the signs of a lousy generator spark plug and some basic ways to help diagnose the problem.

how to fix a generator spark plug

What does a generator spark plug do?

A generator spark plug is a device or tool that provides a spark to ignite the air and fuel mixture inside the combustion chamber of an internal combustion engine.

It’s usually located in the generator engine cylinder head and is designed to create a spark in a small gap that ignites the air and fuel mixture, creating a controlled explosion.

This explosion creates pressure and drives a piston, generating power, which is transmitted to the crankshaft and ultimately to the output shaft of a generator.

By providing a consistent spark, spark plugs help ensure complete combustion, which improves performance, and fuel economy and reduces carbon monoxide emissions.

Spark plugs could be the reason your generator isn’t producing power.

Where are the spark plugs located?

Although the alternator spark plug location varies, it is typically in the engine’s cylinder head. This can be done by removing the air filter or protective cover.

In some cases, the spark plug may be located in a hard-to-reach area, requiring the removal of other components or the engine disassembly. On newer inverter generators, it is located behind the side panels.

In these cases, it is advisable to consult the generator’s owner’s manual for specific instructions and, if needed, seek the assistance of a qualified technician rather than troubleshooting the generator spark plugs yourself.

Once you locate the spark plug, you can remove it using a spark plug socket and ratchet and install it as a new spark plug.

damaged spark plugs in close

What are the symptoms of a bad spark plug?

Should you encounter problems with your generator and are uncertain if a faulty spark plug is the cause, here’s a guide to help you ascertain this.

Your generator may fail to start, or when it does, it won’t function correctly. One prevalent symptom of a bad spark plug is the generator’s inability to initiate when required. In instances where it does start, its operation will be far from normal; it will stutter and eventually shut down once all appliances are connected.

Your generator’s power output will diminish; as previously mentioned, it will shut down when burdened with increased load. This occurs because a defective spark plug is unable to generate the usual power needed for optimal generator function.

Your generator may backfire from its exhaust: If your spark plug is compromised, your generator may backfire, similar to a firearm discharge, particularly when you try to start it after a period of disuse.

How to Determine Generator Spark Plug Failure?

If your generator shows signs of trouble and you don’t know if it’s due to a faulty spark plug, here’s how to find out what’s wrong.

Your generator will not start; if it does, it will not work properly. One of the common signs of a bad spark plug is that the generator didn’t start on time. In the meantime, it doesn’t even work when it starts up wrongly now. It jerks violently and eventually goes out when all the appliances are on.

Your generator will produce less power; as we said, it will go off when the load increases. This is because, due to a faulty spark plug, it will not be able to generate the normal power for the generator to work correctly.

Your generator will shoot out of the exhaust pipe: When your spark plug fails, it will shoot out of the exhaust pipe like a gun, especially if you try to put it on for the first time in a while.

Troubleshooting tips: Steps to diagnose generator spark plug problems

So, before you think your generator spark plug is the cause of the above symptoms, you need to diagnose the problem with your generator.

So here are some things you can do to determine if you need your generator plug repaired.

Step 1: Check the fuel level

When troubleshooting a generator with a faulty spark plug, the first thing to check is the generator’s fuel level.

If the generator tank is empty or the oil level is low, this may be the cause of the generator not starting or working abnormally, not the spark plugs. Therefore, you must ensure the generator tank is filled with fresh fuel.

Step 2: Check the oil level of the generator

A low oil level can also indicate a problem with the generator, such as making noise or even not working correctly. And with some generators, if the oil level is too high, it may burn out the spark plug and make the generator unable to work effectively.

Therefore, you must ensure that the oil level of the generator is at the correct level, and the oil must also be clean and not overdue for replacement.

Step 3: Check the generator filter

Then you need to check the generator for a clogged fuel filter and make sure it is clean, and the fuel in the fuel tank is clear.

However, you shouldn’t just check the clogged section of the filter; you should also check the carburetor’s filter to see if it is dusty and dirty. If yes, wash it down with some fuel.

Step 4: Check for loose or damaged parts

As another step, you should thoroughly inspect the generator for any damaged or loose components that could be causing the problem. This could include a broken fuel line, loose belt, or bolt on the alternator.

Step 5: Check the generator switch

The generator switch is responsible for turning the generator on and off. If the switch is not working correctly, the generator may not start or shut down properly when needed. It might even be shooting.

Therefore, you must make sure to check the switch on the generator to see if it is in good working order.

Step 6: Check the spark plugs

Lastly, you need to check the generator spark plug, as it is responsible for igniting the fuel in the engine. If it is malfunctioning or not working correctly, the generator will not even start or start but cannot power the necessary equipment.

So check the spark plugs and ensure they are in good condition and properly tightened.

manual spark plug replacement

How to repair a generator spark plug

So you’ve diagnosed a problem with your generator and discovered something wrong with the spark plugs.

So, here are some ways to fix a generator spark plug:

  • First, turn off the generator and unplug it from the outlet.
  • Second, find the spark plugs. It’s usually located near the top of the engine.
  • Then, use a spark plug wrench to safely remove the spark plugs from the engine.
  • Obtain new spark plugs that are compatible with your generator.
  • Finally, install the new spark plugs according to the manufacturer’s instructions. After installing the spark plugs, start the generator and test it to ensure it runs smoothly.


It can be frustrating and exhausting whenever your generator starts having spark plug problems. However, it is important to follow the available tips listed by China BISON when the problem arises.

However, if you have tried everything and still cannot diagnose the problem with your generator. In this case, it’s a good idea to contact a BISON China spark plug manufacturer who can help diagnose generator problems (check out more of BISON’s services) to see if there’s a problem with the spark plug if it needs to be repaired and if it needs to be replaced.

fix generator spark plug FAQ

Spark plug replacement depends on various factors, such as environment, usage, and the quality of the spark plugs.

However, as a general rule, replacing the spark plugs every 100 to 150 hours of operation or annually, whichever comes first, is recommended.

It’s also a good idea to periodically inspect the spark plugs for signs of wear, such as contaminated or damaged electrodes, and replace them if necessary.

Regular maintenance helps keep your generator running efficiently and prolongs its life. It is also essential to use high-quality spark plugs designed for your generator’s specific make and model to ensure optimum performance.

When spark plugs turn black, it indicates incomplete combustion. This can trigger various problems including diminished power, elevated fuel usage, and occasionally, it may even prevent the engine from starting.

contact us

Please complete our contact form and we will soon get back to you with expert advice.


Get in touch to speak with our experts!

how to clean a spark plug

how to clean a spark plug?

BISON will walk you through the process step by step, explaining the importance of keeping your spark plugs clean, identifying the signs of a dirty spark plug.


How To Change Generator Spark Plug?

Replacing your spark plugs will improve your engine’s efficiency and extend its life. This article will show you how to replace a worn spark plug step by step.

enquire today

Speak with our sales manager today for additional information or an obligation-free quote.