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Gas Lawn Mower Sputtering: 6 Effective Techniques to Solve the Issue

Gas Lawn Mower Sputtering: 6 Effective Techniques to Solve the Issue

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If your gas lawn mower is sputtering, it could be due to issues with the spark plug or carburetor. A sputtering gas lawn mower can cause uneven lawn cutting and hinder the mower’s performance.

To resolve this issue, checking and cleaning or replacing the spark plug and carburetor may be necessary.

Understanding The Issue

A gas lawn mower sputtering can be a frustrating problem for any lawn owner. The inconsistent engine performance can disrupt the cutting process and leave your lawn with an uneven finish. To tackle this issue effectively, it is essential to understand the underlying causes and know what signs to look for.

Common Signs Of A Sputtering Gas Lawn Mower

Before delving into the factors contributing to a sputtering gas lawn mower, let’s first familiarize ourselves with the common signs that indicate a problem. By recognizing these signs, you can take immediate action to resolve the issue and get your mower running smoothly again.

Here are the typical signs that your gas lawn mower may be sputtering:

  1. Intermittent power loss during operation
  2. Unusual sounds or vibrations coming from the engine
  3. Difficulty starting the mower
  4. Black or white smoke emission
  5. Uneven cutting performance

If you notice any of these signs while using your gas lawn mower, it’s essential to address the problem promptly to prevent further damage. Ignoring the sputtering issue may lead to stalling, permanent engine damage, or even a complete breakdown.

Factors That Contribute To Sputtering

Several factors can contribute to a gas lawn mower sputtering. Understanding these causes can help you identify the underlying issue and find an appropriate solution.

Fuel-related Factors Engine-related Factors Maintenance-related Factors
  • Old gas or contaminated fuel
  • Clogged fuel filters
  • Improper fuel-air mixture
  • Spark plug problems
  • Ignition system issues
  • Carburetor malfunction
  • Damaged or dirty air filter
  • Blocked or restricted airflow
  • Lack of routine maintenance

By examining these factors and assessing their potential presence in your gas lawn mower, you can troubleshoot and address the sputtering issue more effectively. Understanding the root cause will enable you to take appropriate actions such as cleaning or replacing parts, adjusting the fuel mixture, or conducting regular maintenance.

Technique 1: Check The Fuel System

When your gas lawn mower starts sputtering, one of the first things you should do is check the fuel system. A faulty fuel system can cause inadequate fuel flow, leading to poor engine performance and sputtering. In this technique, we will cover three important aspects of the fuel system to inspect, which are:

Inspect The Fuel Tank For Contamination

A contaminated fuel tank can be a major culprit behind your sputtering gas lawn mower. Over time, debris, dirt, and water can accumulate in the fuel tank, clogging the fuel lines and causing irregular fuel flow. To check the fuel tank for contamination:

  • Inspect the exterior of the fuel tank for any visible signs of damage or corrosion. Look for any cracks, holes, or rust that could allow contaminants to enter the fuel system.
  • Remove the fuel cap and visually inspect the interior of the tank. Look for any sediment, debris, or water accumulation. If you notice any contaminants, it’s crucial to clean the fuel tank before moving on to the next steps.
  • Use a clean, dry cloth to wipe the interior of the tank and remove any debris or water.

Check The Fuel Line For Blockages

A blocked fuel line can disrupt the fuel flow to the engine, leading to sputtering and poor performance. To check for fuel line blockages:

  1. Locate the fuel line connecting the fuel tank to the engine.
  2. Carefully inspect the entire length of the fuel line for any kinks, bends, or visible blockages.
  3. If you spot any blockages, gently clear them using a small brush or compressed air. Be cautious not to damage the fuel line while doing so.

Clean Or Replace The Fuel Filter

A clogged or dirty fuel filter can restrict the fuel flow, causing sputtering and decreased engine performance. Cleaning or replacing the fuel filter is an essential step in troubleshooting your sputtering gas lawn mower:

  • Locate the fuel filter, usually found between the fuel tank and the carburetor.
  • Inspect the fuel filter for any signs of dirt, debris, or clogs. If the filter is excessively dirty or damaged, it’s best to replace it with a new one.
  • If the filter appears dirty but still functional, carefully clean it by rinsing it with clean gasoline or using a specialized fuel filter cleaner.
  • Once cleaned or replaced, reattach the fuel filter, ensuring it’s securely connected.

By inspecting the fuel tank for contamination, checking the fuel line for blockages, and cleaning or replacing the fuel filter, you can eliminate potential fuel system issues that might be causing your gas lawn mower to sputter. These simple steps can help restore your lawn mower’s performance and ensure smooth operation.

Technique 2: Examine The Carburetor

One of the main reasons why your gas lawn mower may be sputtering is a problem with the carburetor. The carburetor is responsible for mixing fuel and air in the right proportions for combustion. If it gets clogged with debris or damaged, it can disrupt the fueling process and cause your mower to sputter. Therefore, examining the carburetor should be the next step in troubleshooting this issue. Here’s what you need to do:

Assess The Carburetor For Debris Or Damage

The first thing you should do is visually inspect the carburetor for any signs of debris or damage. Start by locating the carburetor, which is usually a metal part attached to the engine. Check if there are any visible blockages such as dirt, grass clippings, or rust. In case you notice any damage, such as cracks or corrosion, it may need to be repaired or replaced.

Adjust The Carburetor Settings If Necessary

If you don’t find any debris or damage, the next step is to adjust the carburetor settings. Examine the adjustment screws on the carburetor, generally labeled as “H” for high-speed and “L” for low-speed. These screws control the fuel-air mixture. To begin, turn the screws clockwise until they stop, and then slowly turn them counterclockwise. Make small adjustments in both directions, testing the mower after each adjustment, until you find the optimal settings where the mower runs smoothly without any sputtering.

Clean Or Rebuild The Carburetor

If the previous steps haven’t resolved the issue, it’s time to clean or rebuild the carburetor. Cleaning the carburetor involves disassembling it and removing any dirt or debris using carburetor cleaner or compressed air. Rebuilding the carburetor, on the other hand, requires replacing worn-out or damaged parts. Both tasks may require some technical knowledge, so if you’re not comfortable doing it yourself, it’s advisable to take your mower to a professional technician.

By examining the carburetor, assessing it for debris or damage, adjusting the settings if necessary, and cleaning or rebuilding it if needed, you can effectively troubleshoot the sputtering issue with your gas lawn mower. Don’t forget to regularly maintain and clean the carburetor to prevent future problems and keep your mower running smoothly.

Technique 3: Evaluate The Spark Plug

Remove And Inspect The Spark Plug

If your gas lawn mower is sputtering, it could be due to a faulty or dirty spark plug. The spark plug plays a crucial role in igniting the fuel mixture in the engine. Over time, it can accumulate dirt, carbon deposits, or even wear out. To determine if the spark plug is the culprit, start by removing and inspecting it.

Clean Or Replace The Spark Plug If Needed

If the spark plug appears dirty, it’s necessary to clean it. This can be done by carefully removing any debris or carbon buildup using a wire brush or a spark plug cleaner tool. If the spark plug is severely fouled or damaged, it’s best to replace it with a new one. Make sure to consult the manufacturer’s guidelines or your lawn mower’s manual for the right spark plug replacement.

Set The Proper Spark Plug Gap

Another important aspect in evaluating the spark plug is setting the proper spark plug gap. The gap refers to the distance between the center and ground electrode. Incorrect gap spacing can result in misfires or poor ignition, leading to sputtering. To ensure optimal performance, use a spark plug gap tool to measure and adjust the gap according to the manufacturer’s specifications.

Technique 4: Address The Air Filter

When it comes to troubleshooting a gas lawn mower sputtering issue, addressing the air filter can prove to be a simple yet effective solution. The air filter plays a crucial role in allowing clean air to reach the engine, ensuring optimal performance. Over time, the air filter can become clogged with dirt and debris, hindering proper air circulation and causing the mower to sputter.

Remove And Clean The Air Filter

One of the first steps to take in addressing the air filter is to remove and clean it. Follow these simple steps:

  1. Locate the air filter housing on your lawn mower. It is usually a rectangular or cylindrical box made of plastic, attached near the carburetor or on top of the engine.
  2. Carefully remove the housing cover by unscrewing or unclipping it, exposing the air filter.
  3. Take out the air filter and inspect it for dirt, dust, or debris accumulation. If the filter looks dirty or clogged, it’s time to clean and rejuvenate it.
  4. To clean the air filter, gently tap it on a hard surface or use compressed air to remove any trapped dirt. You can also rinse it with water if necessary.
  5. Allow the air filter to dry completely before placing it back into the housing.

By regularly removing and cleaning the air filter, you can ensure that it remains free from debris and works efficiently.

Replace The Air Filter If It’s Worn Or Damaged

If cleaning the air filter doesn’t seem to improve the sputtering issue, it may be a sign that the filter is worn or damaged beyond repair. In such cases, it’s recommended to replace the air filter with a new one. Here’s how:

  1. Refer to your lawn mower’s user manual to identify the correct replacement air filter that fits your specific model.
  2. Remove the old air filter from the housing following the steps mentioned earlier.
  3. Take the new air filter and insert it into the housing, making sure it fits snugly.
  4. Secure the housing cover back in place, ensuring all screws or clips are tight.

Replacing a worn or damaged air filter will not only improve the engine’s performance but also prevent further damage to the mower.

Ensure Proper Air Circulation

It is essential to ensure proper air circulation around the mower. Keep the following tips in mind:

  • Do not operate the lawn mower in an enclosed or overly confined space as it restricts air intake.
  • Ensure that the air intake vents on the mower are not blocked by grass clippings, debris, or other obstructions.
  • Regularly check and clean the cooling fins and engine shroud to prevent overheating caused by restricted airflow.

By paying attention to these aspects, you can maintain proper air circulation, allowing the engine to run smoothly and reducing the chances of sputtering.

Technique 5: Check The Ignition System

A sputtering gas lawn mower can be frustrating, especially when you’re trying to maintain a perfectly manicured lawn. One of the main causes of sputtering issues can be traced back to the ignition system. This crucial component is responsible for creating the spark that ignites the fuel, allowing your lawn mower to run smoothly. In this section, we’ll walk you through three essential steps to effectively check and troubleshoot the ignition system. By inspecting the ignition coil for faults, testing the ignition switch and kill switch, and replacing any faulty ignition components, you can get your gas lawn mower up and running in no time!

Inspect The Ignition Coil For Faults

If your gas lawn mower is sputtering, a faulty ignition coil could be to blame. The ignition coil is responsible for generating the electrical current needed to create the spark. Over time, it can wear out or become damaged, hindering its ability to produce a strong spark. To inspect the ignition coil, follow these steps:

  1. Disconnect the spark plug wire from the spark plug.
  2. Use a multimeter set to the ohms function and touch the meter’s probes to the ignition coil’s terminals.
  3. If the resistance reading is outside the manufacturer’s specified range, it indicates a faulty ignition coil that needs to be replaced.

Test The Ignition Switch And Kill Switch

Another potential culprit behind a sputtering gas lawn mower is a malfunctioning ignition switch or kill switch. These switches control the flow of electricity to the ignition system and can cause intermittent spark issues if they’re not functioning properly. To test these switches, follow these steps:

  1. Disconnect the spark plug wire from the spark plug.
  2. Trace the wires from the ignition switch and kill switch to their respective connectors.
  3. Use a multimeter set to the continuity function and touch the probes to the connectors.
  4. If there is no continuity when the switches are in the ON position or if there is continuity when the switches are in the OFF position, it indicates a problem with either switch that needs to be addressed.

Replace Any Faulty Ignition Components

If you’ve identified a faulty ignition coil, ignition switch, or kill switch during your inspection and testing, it’s crucial to replace these components promptly. Ignoring faulty ignition components can lead to further damage and continued sputtering issues. Consult your mower’s manual or the manufacturer’s website for instructions on obtaining and replacing the specific faulty ignition component. Once you’ve replaced the component, reassemble the ignition system and test your gas lawn mower to ensure that the sputtering issue has been resolved.

Technique 6: Maintenance And Care

Regularly cleaning and maintaining your gas lawn mower is essential for keeping it running smoothly and preventing sputtering issues. In this section, we will discuss how to clean and maintain your lawn mower, the importance of using clean fuel, and proper storage practices.

Regularly Clean And Maintain The Lawn Mower

To ensure optimal performance of your gas lawn mower, it is crucial to keep it clean and well-maintained. Here are some maintenance tips:

  • Clean the underside of the mower deck after each use to remove grass clippings and debris that can clog the blades.
  • Periodically check and clean the air filter to prevent dirt and debris from entering the engine, which can cause sputtering.
  • Inspect the spark plug and replace it if necessary. A fouled spark plug can lead to misfires, resulting in sputtering.
  • Keep the mower’s blades sharp by sharpening or replacing them regularly. Dull blades can cause uneven cutting, putting extra strain on the engine.

Use Clean And Fresh Fuel

The quality of fuel you use in your gas lawn mower can greatly impact its performance. Follow these guidelines for using clean and fresh fuel:

  1. Always use fresh gasoline from a clean container. Stale fuel can lead to clogged fuel lines and carburetor issues, resulting in sputtering.
  2. Do not use fuel that contains more than 10% ethanol, as higher ethanol content can damage the engine over time.
  3. Consider using a fuel stabilizer if you anticipate storing your lawn mower for an extended period. This will help prevent fuel degradation and keep it fresh.

Follow Proper Storage Practices

Properly storing your gas lawn mower during periods of non-use is crucial to maintain its performance and prevent sputtering issues. Here are some storage tips:

  1. Before storing the mower, drain the fuel tank or add a fuel stabilizer to prevent the fuel from deteriorating.
  2. Clean the mower thoroughly, removing any grass clippings or debris that could attract moisture and lead to corrosion.
  3. Store the lawn mower in a cool, dry place, away from extreme temperatures and humidity.
  4. If possible, store the mower in an upright position to prevent oil leakage.

By following these maintenance and care practices, you can keep your gas lawn mower in top condition and ensure smooth, sputter-free operation. Remember, a well-maintained mower not only performs better but also lasts longer, saving you time and money in the long run.

Frequently Asked Questions For Gas Lawn Mower Sputtering

Why Is My Lawn Mower Running Choppy?

A choppy lawn mower is often caused by a dirty or clogged air filter, a damaged spark plug, or old, contaminated fuel. Check and clean the air filter, replace the spark plug if necessary, and use fresh fuel to improve the mower’s performance.

Why Does My Lawn Mower Sound Like It’s Struggling?

A struggling sound from your lawn mower indicates possible issues with the engine or blade. Check if the spark plug is clean and properly gapped, the air filter is clean, and the fuel is fresh. Dull or damaged blades may also cause the mower to struggle.

Why Does My Lawn Mower Start Then Sputter?

Your lawn mower may start and then sputter due to a few reasons. It could be a dirty air filter, a clogged fuel line, or old fuel. Check and clean your air filter, ensure the fuel line is clear, and use fresh fuel.

Why Does My Lawn Mower Sound Like It’s Going To Stall?

Your lawn mower may sound like it’s going to stall due to several reasons such as a clogged air filter, dirty spark plug, or low fuel. Regular maintenance can help resolve these issues and keep your mower running smoothly. Consider checking and cleaning these components for optimal performance.


If your gas lawn mower is sputtering, don’t panic. By following the troubleshooting tips mentioned in this blog post, you can easily identify and fix the issue. Remember to regularly maintain your lawn mower, clean the air filter, check the spark plug, and use clean fuel.

With these simple steps, you can have your gas lawn mower running smoothly and efficiently in no time. Take care of your mower, and it will take care of your lawn. Happy mowing!

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