Why Is My Lawn Mower Spark Plug Black? Here’s The Correct Answer!

Good day!

As a lawn mower owner, keeping tabs on your machine’s maintenance is essential. One of the critical components is the spark plug. It’s responsible for igniting the fuel in the engine. 

However, you may notice that this part turns black, which could indicate a problem. Why is my lawn mower spark plug black? This article will explore the causes and tips to prevent this issue.

Let’s scroll down and dive into it!

Why Is My Lawn Mower Spark Plug Black? 

The primary causes include: 

  • Dirty components
  • Faulty carburetor
  • Incorrect heat rating
  • Inaccurate mixture
  • Clogged air filter 
  • Black shooting
  • Old oil

What causes lawn mower spark plugs to turn black? Keep reading to discover in-depth explanations and how to make this component clean!

Dirty Components

Dirty components are among the most common reasons for a black spark plug. Over time, dirt and debris accumulate on the components of your lawn mower. 

This problem can cause this component to become blackened due to the buildup of carbon deposits. So, regular cleaning and maintenance of your lawn mower can help prevent this issue.

Disconnected, dirty or fouled spark plugs

Faulty Carburetor

Another potential cause of a black spark plug is a faulty carburetor. A malfunctioning carburetor can cause your lawn mower to run too rich.

It means there is too much fuel and not enough air in the combustion chamber. This issue can result in a blackened spark plug.

Incorrect Heat Rating

The heat rating of your spark plug is also an essential factor to consider. If the heat rating of this component is too low, it can cause incomplete combustion and a buildup of carbon deposits. Eventually, it results in a black spark plug. 

Ensuring your lawn mower has the correct heat rating helps prevent this issue.

Inaccurate Mixture

Your lawn mower’s fuel and air mixture must be accurate for efficient combustion. If the blend is too rich, it can cause a black spark plug. 

Yet, if the mixture is too lean, it can cause a white or gray spark plug. So, regularly checking and adjusting the fuel and air mixture can help prevent this issue.

Clogged Air Filter 

A clogged air filter can also cause a black spark plug. A dirty air filter can restrict airflow to the combustion chamber. It causes incomplete combustion and a buildup of carbon deposits. 

You need regularly cleaning or replacing your air filter to help prevent this issue.

Black Shooting

Black shooting is another reason for a black spark plug. It occurs when the engine is not firing correctly. 

The fuel may not be appropriately ignited, causing it to burn incompletely and produce black smoke. It can also result in a black spark plug.

Old Oil

Finally, using old or contaminated oil can cause a black spark plug. Old oil can become thick and sticky, so the fuel may clog the engine and affect the combustion process. It can result in black smoke and a black spark plug.

How To Clean Black Spark Plugs? 

How long does a lawn mower spark plug last?

Cleaning black spark plugs is a straightforward process you can do at home with the right tools. 

Following these steps will ensure that these components perform optimally!

Step 1: Gather the tools

Before cleaning these parts, you need to gather some tools. You will need these things

  • A wire brush
  • A spark plug cleaner
  • A basin of water
  • A lint-free cloth

Step 2: Immerse the spark plug

Remove the spark plug from the engine. Next, use a wire brush to eliminate any loose dirt or debris. 

Fill a basin with water and immerse the component, ensuring it is fully submerged. Allow the spark plug to soak for around 30 – 40 minutes.

Step 3: Wash the spark plug with running water

After soaking the spark plug, remove it from the water and use a spark plug cleaner to remove any remaining debris or soot. 

Hold this component under running water and use the cleaner to scrub it clean thoroughly.

Step 4: Wipe off the spark plug

After washing this part thoroughly, use a lint-free cloth to wipe it dry. Eliminate any moisture accumulated during the cleaning process.

Step 5: Dry the spark plug 

Finally, completely dry the spark plug using compressed air or a heat gun. Ensure no moisture is left on the piece before reinstalling it in the engine.

How To Prevent Lawn Mower Spark Plug From Turning Black? 

How To Prevent Lawn Mower Spark Plug From Turning Black?

With simple tips, you can prevent your mower spark plug from turning black and keep your machine running smoothly. Check our guides below!

Change The Oil Regularly

Regular oil changes are essential for the proper functioning of any engine, including mowers. Over time, old oil can become contaminated with dirt, debris, and other particles. 

This issue can lead to increased wear and tear on the engine. It eventually causes the spark plug to turn black. You should change the oil in your lawn mower every 50 hours of use or at least once a year.

Clean The Spark Plug

Another effective way to prevent your lawn mower spark plug from turning black is to clean it regularly. 

Dirt and debris can gradually accumulate on the component, which can cause it to malfunction. You need to remove this component from the engine and use a wire brush to clear any dirt and debris. 

Ask For Professional Help

If you have tried changing the oil and cleaning the spark plug, but it still turns black, it is time to seek professional help. 

A qualified technician can inspect your lawn mower and diagnose any underlying issues causing this part to turn black. 

Furthermore, they can perform routine maintenance to ensure your machine runs smoothly and efficiently.

The Bottom Line

A black spark plug is a common problem that many lawn mower owners face. Dirty components, faulty carburetor, and other reasons can cause it. 

Luckily, you can fix this problem and help your mower run smoothly again with our simple guides.

If you notice any issues with your machine, ask a professional mechanic for advice and repair!

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