If your lawn mower is smoking and sputtering, it could be due to an overfilled oil reservoir or oil spilled onto the engine, causing white smoke. Additionally, a dirty or clogged air filter may prevent sufficient airflow into the carburetor, leading to black exhaust smoke.

These issues affect the gasoline to air mixture, resulting in sputtering and smoking. To resolve this, it’s important to address the oil level and cleanliness of the air filter in your lawn mower. Neglecting these factors can lead to an inefficient fuel mixture and poor engine performance.

By understanding the common causes of smoking and sputtering in lawn mowers, you can effectively maintain and troubleshoot your equipment for optimal performance.

Why Is My Lawn Mower Smoking And Sputtering

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Common Causes Of Smoking And Sputtering

Possible causes of smoking and sputtering in a lawn mower include an overfilled oil reservoir, oil spilled onto the engine, a dirty or clogged air filter, a faulty fuel pump, or a carburetor issue. These issues can result in white or black smoke being emitted from the mower.

Common Causes of Smoking and Sputtering

Overfilled Oil Reservoir

An overfilled oil reservoir can lead to smoking and sputtering. When the oil level exceeds the recommended amount, it may spill onto the engine, causing excessive smoke and erratic engine performance. To remedy this issue, carefully drain the excess oil and ensure the oil level is within the specified range.

Oil Spilled Onto The Engine

If oil has spilled onto the engine, it can result in smoking and sputtering. This can occur if the oil filler cap is not properly secured or if the mower is tilted incorrectly during refueling. To address this, clean any spilled oil from the engine and ensure the oil cap is tightly sealed to prevent further leaks.

Dirty Or Clogged Air Filter

A dirty or clogged air filter can cause smoking and sputtering in a lawn mower. When the air filter becomes obstructed, it restricts airflow to the engine, leading to an imbalanced fuel mixture and poor combustion. Regularly inspect and clean or replace the air filter to ensure proper engine performance.

Malfunctioning Carburetor

A malfunctioning carburetor can contribute to smoking and sputtering issues. If the carburetor is not receiving sufficient air, it can result in a fuel-rich mixture, leading to black exhaust smoke and erratic engine operation. Inspect and clean the carburetor, and adjust the air-fuel mixture as needed to resolve this problem.

Leaking Oil From The Exhaust

Leaking oil from the exhaust can cause smoking and sputtering, indicating potential damage or wear in the engine components. Addressing this issue may require professional inspection and repair to prevent further damage to the mower.

Fixing The Issues

Experiencing smoke and sputtering from your lawn mower? The likely culprits are an overfilled oil reservoir or spilled oil on the engine. A dirty or clogged air filter can also cause black exhaust smoke. Clearing the air filter and adjusting the oil levels can often resolve these issues, ensuring your lawn mower operates smoothly.

Draining Excess Oil

To drain excess oil from your lawn mower, follow these simple steps:

  1. Locate the oil drain plug beneath the mower.
  2. Place a container under the plug and unscrew it.
  3. Let the old oil drain completely.
  4. Once drained, replace the plug securely.

Cleaning Spilled Oil

Clean spilled oil by:

  • Using a degreaser to loosen the oil stains.
  • Scrubbing the affected area with a brush.
  • Rinsing off the degreaser with water.
  • Drying the area thoroughly with a clean cloth.

Replacing Or Cleaning The Air Filter

To replace or clean the air filter, follow these steps:

  1. Locate the air filter cover and remove it.
  2. Take out the old air filter and inspect it for dirt and damage.
  3. If reusable, clean the filter with soap and water, then let it dry completely.
  4. If not reusable, replace with a new filter of the same size and type.
  5. Place the cleaned or new filter back into the housing and reattach the cover securely.

Repairing Or Replacing The Carburetor

To repair or replace the carburetor:

  1. Disconnect the fuel line and remove the carburetor from the engine.
  2. Clean the carburetor with a carburetor cleaner and compressed air.
  3. Inspect for any damage or wear and replace any faulty parts if necessary.
  4. Reassemble the carburetor and reinstall it onto the engine.

Fixing The Leaky Exhaust

Repair a leaky exhaust by:

  1. Identifying the location of the leak in the exhaust system.
  2. Applying high-temperature epoxy or sealing tape to the damaged area.
  3. Allowing the repair to cure completely before running the mower again.

Preventive Maintenance

Proper preventive maintenance is key to keep your lawn mower running smoothly and to prevent issues like smoking and sputtering. By following a few simple maintenance tasks, you can ensure that your lawn mower stays in top shape and avoids unnecessary damage. Here are some essential tasks to include in your preventive maintenance routine:

Properly Maintaining Oil Levels

One of the most important preventive maintenance tasks for your lawn mower is to regularly check and maintain the oil levels. Low oil levels can cause excessive friction and overheating, leading to smoking and sputtering. On the other hand, overfilling the oil reservoir can also cause smoking. To properly maintain the oil levels:

  1. Refer to your lawn mower’s user manual to determine the recommended oil type and capacity.
  2. Check the oil level before each use, ensuring it is within the recommended range.
  3. If the oil level is low, add the appropriate amount of oil, making sure not to overfill.
  4. Regularly change the oil according to the manufacturer’s recommendations.

Cleaning The Mower After Each Use

Another important preventive maintenance step is to clean your mower after each use. Grass clippings, dirt, and debris can accumulate on and around the mower, obstructing airflow and causing overheating. To properly clean your lawn mower:

  1. Allow the mower engine to cool down completely.
  2. Use a brush or compressed air to remove grass clippings and debris from the mower deck, blades, and air vents.
  3. Inspect and clean the spark plug area to remove any dirt or grime that may affect ignition.
  4. Wipe down the exterior of the mower with a damp cloth to remove any remaining dirt or debris.

Regularly Cleaning The Air Filter

The air filter plays a crucial role in providing clean air to the engine for proper combustion. A dirty or clogged air filter can restrict airflow, leading to a rich fuel mixture and potential smoking. To maintain a clean air filter:

  1. Refer to your lawn mower’s user manual to locate the air filter.
  2. Remove the air filter cover and inspect the filter for dirt and debris.
  3. If the filter is dirty, clean it using compressed air or by tapping it gently to remove loose debris.
  4. If the filter is heavily clogged, it may need to be replaced with a new one.

Inspecting And Cleaning The Carburetor

The carburetor is responsible for mixing fuel and air in the correct proportions for combustion. A dirty or clogged carburetor can disrupt this balance, resulting in black exhaust smoke. To inspect and clean the carburetor:

  1. Refer to your lawn mower’s user manual to locate the carburetor.
  2. Remove the carburetor cover and inspect it for dirt, debris, or clogs.
  3. Use a carburetor cleaner or a small brush to carefully clean the carburetor components.
  4. Reassemble the carburetor and ensure it is properly attached to the engine.

Checking For Leaks And Addressing Them Promptly

Leaks in the fuel system or engine can lead to smoking and sputtering. Regularly check for leaks and address them promptly to prevent further damage. To check for leaks:

  1. Inspect the fuel lines, fuel tank, and engine for any signs of leakage.
  2. If you notice any leaks, shut off the engine and repair or replace the affected components.
  3. Ensure all connections are tight and secure.

By incorporating these preventive maintenance tasks into your lawn mower care routine, you can prolong the life of your mower and minimize the risk of smoking and sputtering issues. Remember to always follow the manufacturer’s guidelines for maintenance and consult a professional if you are unsure or unable to perform any maintenance tasks yourself.

Why Is My Lawn Mower Smoking And Sputtering

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Troubleshooting Tips

When your lawn mower starts smoking and sputtering, it can be a cause for concern. However, with some troubleshooting tips, you can identify the issue and fix it yourself. Let’s explore some common reasons behind your lawn mower smoking and sputtering and how to address them.

Checking Spark Plugs

One of the first things to check when your lawn mower is smoking and sputtering is the condition of the spark plugs. Make sure they are clean and free of any build-up. Replace them if necessary.

Inspecting The Fuel Line

Check the fuel line for any leaks or blockages. Ensure proper fuel flow to keep the engine running smoothly.

Examining The Ignition System

Inspect the ignition system components such as the coil, magneto, and connections. Ensure everything is in good working order.

Ensuring Proper Fuel Mixture

Check the fuel mixture to ensure it is appropriate for your lawn mower. Adjust as needed to maintain optimal performance.

Inspecting The Cooling System

Ensure the cooling system is working efficiently to prevent overheating, which can lead to smoking and sputtering issues.

When To Seek Professional Help

When experiencing persistent smoking and sputtering, it may be time to seek professional help to avoid further issues.

Persistent Smoking And Sputtering

If your lawn mower continues to emit smoke and sputter despite troubleshooting, it’s best to consult a professional for expert diagnosis and repair.

Lawn Mower Not Starting

When your lawn mower refuses to start even after attempts to fix the issue, professional assistance is recommended to avoid worsening the problem.

Other Mechanical Issues

In case of unidentified mechanical issues with your mower, seeking help from a professional can ensure that the problem is correctly identified and resolved.

Why Is My Lawn Mower Smoking And Sputtering

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Frequently Asked Questions Of Why Is My Lawn Mower Smoking And Sputtering

Why Is My Lawn Mower Sputtering And Blowing White Smoke?

Your lawn mower may be sputtering and blowing white smoke due to overfilled oil reservoir or oil spilled onto the engine causing engine smoking. Another reason could be a dirty or clogged air filter preventing sufficient airflow into the carburetor.

Regular maintenance and proper oil levels can help resolve this issue.

Why Is My Lawn Mower Popping And Smoking?

The likely reasons for a popping and smoking lawn mower include an overfilled oil reservoir or oil spilled onto the engine. The carburetor might be clogged or have a dirty air filter, causing black exhaust smoke. Ensure appropriate oil levels and clean or replace the air filter to fix the issue.

Why Is My Lawnmower Smoking White And Spitting Oil?

Your lawnmower is smoking white and spitting oil due to overfilled oil reservoir or spilled oil.


When your lawn mower is smoking and sputtering, it can be a cause for concern. The likely reasons for this issue include an overfilled oil reservoir, oil spilled onto the engine, a dirty or clogged air filter, or a carburetor issue.

To fix these problems, you may need to change the air filter, adjust the oil level, or clean the carburetor. By addressing these issues, you can ensure your lawn mower runs smoothly and efficiently. Remember to perform regular maintenance to prevent future problems and keep your lawn mower in optimal condition.

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