Why is My Lawn Mower Turning Over But Not Starting?

If your lawn mower turning over but not starting, the most common reason is bad gas. Gas that sits for an extended period can cause fuel degradation and clog the carburetor, making it difficult for the engine to start.

Additionally, a dirty or disconnected spark plug, a dirty air filter, or a faulty fuel pump can also prevent your lawn mower from starting. It is recommended to drain the fuel tank and fill it with fresh gas, clean or replace the spark plug and air filter, and check the fuel pump for any issues.

Common Causes Of Mower Not Starting

When it comes to lawn mower maintenance, one of the most frustrating issues that can arise is when your mower turns over but doesn’t start. This can leave you scratching your head, wondering what could be causing the problem. Fortunately, there are common causes for this issue that you can easily troubleshoot and fix yourself. Let’s take a look at three common culprits: bad or old gas, problems with the spark plug, and a dirty air filter.

Bad Or Old Gas

One of the main reasons your lawn mower may not be starting could be due to bad or old gas. Over time, gasoline can become stale and lose its effectiveness, making it difficult for your mower’s engine to ignite. If you haven’t used your mower in a while, or if you left gas sitting in the tank over the winter, it’s essential to drain the fuel tank and fill it with fresh gas. This simple solution can often solve the problem and get your mower up and running again.

Problems With The Spark Plug

Your lawn mower’s spark plug plays a crucial role in igniting the fuel mixture in the engine combustion chamber. If the spark plug is dirty, damaged, or disconnected, it can prevent your mower from starting. Check the spark plug for any signs of dirt or debris, clean it off, re-connect it if necessary, and make sure it is tightened securely. If the spark plug is beyond repair, it’s easy and affordable to replace it with a new one. This small but essential component can make a big difference in getting your mower started.

Dirty Air Filter

Another common cause for a lawn mower not starting is a dirty air filter. The air filter prevents dirt, debris, and other contaminants from entering the engine and affecting its performance. Over time, the air filter may become clogged, restricting the flow of air to the engine, and preventing proper combustion. It’s recommended to regularly clean or replace the air filter, especially if you are using your mower in dusty or dirty conditions. This simple maintenance task can significantly improve your mower’s starting ability.

Why is My Lawn Mower Turning Over But Not Starting? Troubleshoot the Issue!

Troubleshooting And Solutions

If you find that your lawn mower is turning over but not starting, there are a few common issues that you can troubleshoot and solve yourself. By checking the fuel quality, inspecting and cleaning the spark plug, and cleaning or replacing the air filter, you can often get your lawn mower up and running again.

Check Fuel Quality

One of the first things to check when your lawn mower is not starting is the fuel quality. If you have last season’s gas in your mower, it may have degraded and become less effective. It is recommended to drain the fuel tank completely and replace it with fresh gas. Ensure that you are using the correct fuel mixture for your specific mower model.

Inspect And Clean Spark Plug

A loose, dirty, or disconnected spark plug can also prevent your lawn mower from starting. Begin by removing the spark plug and inspecting it for any debris or signs of damage. Clean the spark plug using a wire brush and check the gap to ensure it is within the manufacturer’s specifications. Reconnect the spark plug tightly and securely.

Clean Or Replace the Air Filter

Start-up problems may arise from an obstructed air filter, which limits the engine’s airflow. Remove the air filter cover and inspect the air filter for any dirt, dust, or debris. If the filter is dirty, clean it by tapping it gently or using compressed air. If the air filter is damaged or excessively dirty, it is recommended to replace it with a new one to ensure proper airflow.

By following these troubleshooting steps and addressing any issues with fuel quality, spark plug cleanliness, and air filter condition, you can often resolve the problem of your lawn mower turning over but not starting. If the issue persists despite these solutions, it may be necessary to consult a professional for further diagnosis and repair.

Issues With The Ignition System


One of the common reasons a lawn mower may turn over but not start is due to issues with the ignition system. The ignition system is crucial as it is responsible for providing the spark needed to ignite the fuel in the engine. Several components such as the ignition coil, battery, and solenoid play a vital role in the ignition system, and any malfunction in these parts can lead to starting issues. Let’s take a closer look at the potential issues and troubleshooting steps for each component.

Inspecting The Ignition Coil

The ignition coil is a critical part of the ignition system that generates the high voltage needed to create the spark. If the ignition coil is faulty or damaged, it can result in a weak or no spark, leading to starting problems. To inspect the ignition coil, follow these steps:

  1. Locate the ignition coil, typically positioned near the flywheel or the engine.
  2. Look for any obvious deterioration indicators, such as rust or cracks.
  3. Test the continuity of the ignition coil using a multimeter to ensure it is functioning properly.

Checking The Battery

The battery provides the necessary electrical power to the ignition system and starter motor. If the battery is weak or defective, it can hinder the starting process.  The following are the steps to check the battery:

  • Check for corrosion on the battery terminals and make sure the connections are tight.
  • Use a multimeter to measure the voltage of the battery, ensuring it meets the manufacturer’s specifications.
  • If the voltage is low, consider recharging or replacing the battery as needed.

Testing The Solenoid

When the ignition key is turned, the solenoid is what activates the starting motor. A faulty solenoid can prevent the starter motor from receiving the necessary electrical current, resulting in starting issues. To test the solenoid:

  1. Check for any corrosion or loose connections on the solenoid terminals.
  2. Use a multimeter to verify that the solenoid is receiving and transmitting the appropriate electrical signal when the ignition key is turned.
  3. If the solenoid fails the test, consider replacing it to rectify the starting problem.


Problems With The Carburetor

Experiencing issues with your lawn mower engine turning over but not starting? This could be due to problems with the carburetor. Common reasons include old gas, a dirty spark plug, or a clogged fuel filter hindering fuel flow to the carburetor.

Checking and cleaning these components may help address the issue.

Cleaning The Carburetor

If you’re experiencing problems with your lawn mower turning over but not starting, one potential issue could be with the carburetor. The carburetor is responsible for mixing the fuel and air in the proper ratios to create combustion. Over time, it can become clogged with dirt, debris, and old fuel, preventing it from functioning correctly. Use these easy procedures to clean the carburetor:

  1. First, take off the air filter cover and unplug the spark plug wire.
  2. Next, locate the carburetor. It is usually situated underneath the air filter cover.
  3. Using a screwdriver, carefully remove the screws holding the carburetor in place.
  4. Gently lift the carburetor and detach any fuel lines connected to it.
  5. Using a carburetor cleaner, spray the inside of the carburetor, ensuring all the small ports and jets are thoroughly cleaned.
  6. Once the carburetor is cleaned, reattach any fuel lines and secure the carburetor back in place.
  7. Put the air filter cover back on and reconnect the spark plug wire.

By cleaning the carburetor, you can remove any build-up that may be preventing the proper flow of fuel, increasing the chances of your lawn mower starting successfully.

Inspecting Fuel Lines

In addition to cleaning the carburetor, it’s essential to inspect the fuel lines for any damage or blockages. Fuel lines are responsible for delivering fuel from the tank to the carburetor, and any issues can lead to a lack of fuel flow, resulting in starting problems.

Use these procedures to check the gasoline lines:

  1. Locate the fuel lines running from the fuel tank to the carburetor.
  2. Check for cracks, leaks, or signs of wear on the fuel lines. If any damage is detected, they may need to be replaced.
  3. Ensure that the fuel lines are properly connected to both the fuel tank and the carburetor.
  4. If there are any blockages, carefully remove the affected fuel line and clean it with compressed air or a small wire brush.
  5. Once the fuel lines are inspected and any issues resolved, reconnect them securely.

Regularly inspecting and maintaining the fuel lines can help ensure proper fuel delivery and prevent starting issues with your lawn mower.

Adjusting The Choke

The choke is another component of the carburetor that can affect the starting of your lawn mower. It regulates the amount of air flowing into the engine during the starting process. If the choke is not adjusted correctly, it can lead to difficulties in starting the mower.

To adjust the choke, follow these steps:

  1. Locate the choke lever or knob, usually situated near the air filter or the carburetor.
  2. Before starting your lawn mower, ensure the choke is in the closed or partially closed position.
  3. If the engine fails to start, try adjusting the choke to a different position, such as fully closed or fully open, depending on the manufacturer’s recommendations.
  4. Continue experimenting with different choke positions until the mower starts smoothly.

By adjusting the choke properly, you can regulate the air-to-fuel ratio and increase the chances of your lawn mower starting successfully.

Additional Troubleshooting Tips

Have trouble with your lawn mower turning over but not starting? Don’t worry, we’ve got some additional troubleshooting tips to help you get to the root of the problem. Check out the steps below to make sure your lawn mower is up and running smoothly again.

Examining Compression

One possible issue when your lawn mower won’t start is a problem with compression. Incorrect compression can prevent the engine from igniting the fuel-air mixture properly. Follow these steps to check the compression on your lawn mower:

  1. First, remove the spark plug wire to ensure the engine does not start accidentally.
  2. Next, remove the spark plug using a spark plug wrench.
  3. Inspect the spark plug for any signs of damage, such as erosion or fouling. Clean or replace the spark plug if needed.
  4. Using a compression tester tool, screw it into the spark plug hole tightly.
  5. Hold the throttle lever in the wide-open position and pull the starter cord to crank the engine a few times.
  6. Note the reading on the compression tester gauge. It should be within the recommended range for your specific lawn mower model. If the compression is too low, you may need to take your lawn mower to a professional for further diagnosis and repair.

Verifying Fuel Pump Operation

If the compression is not the issue, it’s important to also check the fuel pump operation. An issue with the fuel pump may hinder the engine’s ability to receive gasoline in the correct amount. Here’s how to verify if the fuel pump is working correctly:

  1. The gasoline line should be disconnected from the carburetor and put in a container.
  2. Without turning on the engine, flip the ignition switch to the “On” position.
  3. Observe whether fuel flows freely from the fuel line into the container. If there is no fuel or very little fuel coming out, it may indicate a problem with the fuel pump that requires further inspection or replacement.
  4. If fuel is flowing properly, reconnect the fuel line to the carburetor securely.

Addressing Obstructed Passageways

Another common issue that can cause a lawn mower to turn over but not start is obstructed passageways within the fuel system. Debris, dirt, or buildup in the fuel tank, fuel lines, or carburetor can restrict fuel flow. Follow these steps to address any obstructions:

  1. Drain the fuel from the tank and remove any debris or obstructions.
  2. Inspect the fuel lines for any blockages or cracks. Replace them if necessary.
  3. Remove the carburetor bowl and clean it thoroughly with carburetor cleaner, ensuring all passageways are clear of debris.
  4. Reinstall the carburetor bowl and reconnect the fuel lines securely.

By following these additional troubleshooting tips, you can narrow down the potential causes of your lawn mower not starting and hopefully get it back into working condition. It could be prudent to seek expert advice if the problem continues.

Why is My Lawn Mower Turning Over But Not Starting? Troubleshoot the Issue!

Why is My Lawn Mower Turning Over But Not Starting? Troubleshoot the Issue!

FAQs On Why is My Lawn Mower Turning Over But Not Starting

Why Will My Lawnmower Turn Over But Not Start?

If your lawnmower turns over but doesn’t start, it could be due to several reasons. First, check the fuel tank and replace old gas with fresh fuel. Next, inspect and clean the spark plug, ensuring it’s connected tightly. Finish by cleaning or changing the air filter.

What Is The First Thing To Check If A Lawn Mower Won’t Start?

The first thing to check if a lawn mower won’t start is the spark plug. Make sure it is clean, connected properly, and tightened. To clean or replace a filthy spark plug, follow these steps. Additionally, check the fuel tank and make sure it is filled with fresh gas.

Why Does My Lawn Mower Starter Spin But Not Engage?

If your lawn mower starter spins but doesn’t engage, it could be due to a faulty battery or debris in the carburetor. Check the battery and charging system for issues, and clean or replace the spark plug and fuel filter.

Ensure the gas is fresh and the fuel pump is functioning properly.

Why Is My Lawn Mower Not Firing Up?

If your lawn mower is not firing up, there are a few possible causes. First, check if you have old gas in the tank and replace it with fresh fuel. Also, make sure your spark plug is clean and properly connected.

Another potential issue could be a dirty air filter, so try cleaning or replacing it. Finally, check the carburetor for any dirt or debris that may be obstructing fuel flow.


It’s frustrating when your lawn mower turns over but won’t start. However, by following the troubleshooting tips and maintenance advice outlined in this blog post, you can diagnose and resolve the issue. Remember to check the fuel, spark plug, air filter, and ignition system to get your lawn mower running smoothly again.

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