Lawn Mower Sputtering: Causes, Diagnosis, and Fixes

A well-maintained lawn mower is essential for keeping your yard looking its best. However, if your lawn mower is sputtering, it can be both frustrating and challenging to diagnose the issue. In this comprehensive guide, we will discuss the common causes of lawn mower sputtering, how to diagnose the problem, and steps to fix the issue. We will also provide tips for preventative maintenance to ensure your lawn mower stays in top working condition.

Common Causes

Lawn mower sputtering can be caused by several factors:

  • Dirty air filter: A clogged or dirty air filter can restrict airflow to the engine, causing the mower to sputter.
  • Bad spark plug: A worn or damaged spark plug can result in inconsistent sparking, leading to sputtering and poor engine performance.
  • Clogged carburetor: A dirty or clogged carburetor can disrupt the air-fuel mixture, causing the mower to sputter or stall.
  • Old fuel: Stale fuel can cause poor combustion and sputtering in the engine.
  • Water in fuel: Water contamination in the fuel can lead to sputtering and other performance issues.
  • Loose connections: Loose electrical or fuel connections can cause intermittent power issues and sputtering.

Diagnosing the Issue

To diagnose the cause of your lawn mower’s sputtering, follow these steps:

  1. Checking air filter: Examine the air filter for dirt or debris. A dirty air filter can restrict airflow and cause the engine to sputter.
  2. Inspecting spark plug: Check the spark plug for wear or damage. A worn or damaged spark plug can cause inconsistent sparking and sputtering.
  3. Examining carburetor: Inspect the carburetor for signs of clogging or dirt. A clogged carburetor can disrupt the air-fuel mixture and cause sputtering.
  4. Evaluating fuel quality: Assess the fuel in the tank for signs of age or water contamination. Stale fuel or water in the fuel can cause sputtering and poor engine performance.

Fixing the Problem

Once you’ve identified the cause of your lawn mower’s sputtering, follow these steps to fix the issue:

  • Cleaning air filter: If the air filter is dirty or clogged, clean it with mild soap and water, and let it dry completely before reinstalling it. Replace the air filter if it is damaged or worn.
  • Replacing spark plug: If the spark plug is worn or damaged, replace it with a new one to ensure consistent sparking and optimal engine performance.
  • Cleaning carburetor: If the carburetor is dirty or clogged, remove it and clean it using carburetor cleaner. Ensure that all passages are clear before reinstalling the carburetor.
  • Draining old fuel: If the fuel in the tank is old or contaminated, drain it and replace it with fresh fuel. Be sure to dispose of the old fuel properly.
  • Removing water from fuel: If there is water contamination in the fuel, drain the fuel tank and refill it with fresh fuel. You may also use a fuel stabilizer to help prevent future water contamination.
  • Tightening connections: Check for loose electrical or fuel connections and tighten them as needed to ensure consistent power delivery and prevent sputtering.

Preventative Maintenance

To keep your lawn mower running smoothly and prevent sputtering, follow these preventative maintenance tips:

  • Regular filter checks: Check and clean the air filter regularly to ensure optimal airflow to the engine. Replace the air filter as needed.
  • Spark plug care: Inspect the spark plug regularly for wear or damage, and replace it when necessary to maintain consistent sparking and optimal engine performance.
  • Carburetor upkeep: Keep the carburetor clean by using a fuel stabilizer and checking it periodically for signs of clogging or dirt. Clean the carburetor as needed to ensure a proper air-fuel mixture.
  • Fuel storage tips: Store fuel in an approved, tightly sealed container away from heat sources and direct sunlight to prevent fuel degradation and water contamination. Use fuel stabilizers to extend the life of stored fuel and minimize the risk of engine issues.


A sputtering lawn mower can be caused by various factors, including a dirty air filter, a bad spark plug, a clogged carburetor, old fuel, water in the fuel, or lose connections. By diagnosing the issue and addressing the root cause, you can fix your lawn mower’s sputtering problem and restore its performance.

Regular preventative maintenance, such as checking the air filter, spark plug, and carburetor, along with proper fuel storage, can help prevent lawn mower sputtering and ensure your mower stays in top working condition. By keeping your mower well-maintained, you can enjoy a beautiful, well-manicured lawn for years to come.


  • Nathan Collins

    Having spent years working in the landscaping industry, Nathan Collins has cultivated a wealth of knowledge about the natural world. He is committed to helping others appreciate the beauty in their backyards, whether it's through identifying rare rocks and minerals or crafting the perfect landscape.

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