How Do I Get My Lawn Mower to Start?

The sun is shining, the birds are singing, and you’re itching to get your lawn looking pristine. You grab your trusty lawn mower, pull the cord, and… nothing. The familiar roar of the engine is replaced by a disheartening silence. Now what? Don’t worry, you’re not alone. Lawn mower starting troubles are a common occurrence, but with a little troubleshooting, you can have your lawn mowed in no time. This article will guide you through the most common reasons why your lawn mower won’t start and offer step-by-step solutions to get you back on track.

In essence, the problem usually boils down to one of these: fuel issues, spark issues, or a clogged air filter. We’ll examine each of these potential culprits and give you practical tips to diagnose and resolve them.

Fuel Troubles: Are You Running on Empty?

The first step in troubleshooting a non-starting lawn mower is to rule out fuel problems. Even a seemingly full gas tank can harbor issues that prevent your mower from firing up.

1. Check Your Gas:

  • Age Matters: Gasoline goes bad over time, losing its volatile properties and becoming gummy. If the gas in your mower is older than 30 days, it’s best to drain it and replace it with fresh fuel.
  • Fuel Line Issues: Check your fuel line for any cracks, leaks, or kinks. If you find any damage, you’ll need to replace the fuel line.
  • Fuel Filter: A clogged fuel filter can restrict the flow of gas to the engine. Inspect the filter and replace it if necessary.

2. Prime Your Engine:

  • Manual Primer: Many lawn mowers have a primer bulb, usually located near the carburetor. Pump the primer bulb a few times to ensure a good supply of fuel is delivered to the carburetor.
  • Automatic Primer: Some mowers have an automatic primer. If so, ensure the choke is engaged to start the engine.

3. Start It Right:

  • Choke vs. Throttle: When starting a cold engine, the choke should be fully engaged, restricting air intake and enriching the fuel mixture. Once the engine starts, slowly release the choke to allow more air and lean out the mixture.
  • Starter Rope: Pull the starter cord slowly at first, then give it a firm tug.

Spark Problems: Is Your Spark Plug Firing?

If you’ve addressed fuel issues and your lawn mower still won’t start, the problem might lie with the spark plug. The spark plug is responsible for igniting the fuel-air mixture, and a faulty one can prevent the engine from firing.

1. Check the Spark Plug:

  • Remove the Spark Plug: Locate the spark plug, which is usually accessible on the top of the engine. Use a spark plug socket wrench to remove it.
  • Inspect for Damage: Examine the spark plug for any signs of damage, such as cracks, carbon buildup, or erosion.
  • Test for Spark: Connect the spark plug wire to the spark plug, hold the plug against a grounded metal surface, and pull the starter cord. You should see a bright blue spark. If there’s no spark, your spark plug is likely faulty.

2. Replace the Spark Plug:

  • Select the Right Spark Plug: Refer to your owner’s manual for the correct spark plug type for your lawn mower.
  • Install the New Spark Plug: Screw the new spark plug into the spark plug hole, ensuring it’s securely tightened.

Air Filter Blockage: Can Your Engine Breathe?

A clogged air filter can restrict air flow to the engine, making it difficult to start. If you haven’t cleaned or replaced your air filter recently, this could be the culprit.

1. Clean or Replace the Air Filter:

  • Locate the Air Filter: The air filter is typically found in a housing near the carburetor.
  • Remove and Clean: Remove the air filter and clean it with compressed air or a brush. If the filter is heavily soiled, it’s best to replace it.
  • Reinstall the Air Filter: Securely reinstall the clean or new air filter in its housing.

Additional Tips for Starting a Lawn Mower:

  • Check for a Dead Battery: If your lawn mower has an electric start, ensure the battery is charged.
  • Check for a Loose Connection: Inspect all electrical connections, including the spark plug wire, for loose or corroded connections.
  • Consider the Weather: Extreme cold or heat can affect engine performance. Start your mower in a sheltered area if possible.

Seek Professional Help:

If you’ve tried all the troubleshooting steps above and your lawn mower still won’t start, it might be time to call in a professional. A qualified mechanic can diagnose and fix more complex issues, such as carburetor problems, ignition system failures, or engine damage.

Preventative Maintenance:

The best way to avoid lawn mower starting problems is to perform regular maintenance. Here are some tips:

  • Clean the Air Filter: Clean or replace the air filter every 25 hours of use.
  • Change the Spark Plug: Replace the spark plug every 100 hours of use.
  • Drain and Replace the Gas: Drain and replace the gas every 30 days.
  • Store Properly: When not in use, store your lawn mower in a dry, well-ventilated area.


A non-starting lawn mower can be frustrating, but with some basic troubleshooting, you can usually get it running again. Remember to check fuel issues, spark problems, and air filter blockage. By understanding the common causes and how to address them, you can keep your lawn mower in top shape and ready to tackle any mowing job. If you’re still stumped, don’t hesitate to call a professional for help. Happy mowing!


What are the most common reasons my lawn mower won’t start?

The most common reasons your lawn mower won’t start are a dead battery, a clogged air filter, bad gas, or a fouled spark plug. You’ll also want to check if the fuel shut-off valve is open. Sometimes, a simple solution like checking the fuel line can get your lawn mower running again.

Before assuming it’s something more complicated, try these simple checks first. These are the most common issues that cause a lawn mower to refuse to start.

How do I check the battery on my lawn mower?

To check the battery, simply connect a voltmeter to the battery terminals. If the voltmeter reads less than 12 volts, then your battery is dead and needs to be replaced. Make sure the battery terminals are clean and free of corrosion. A dirty battery can prevent a good electrical connection, making it seem as if the battery is dead when it isn’t.

You can try jumping the battery with another battery to see if that will get the mower started. If not, you’ll need to replace the battery. Be sure to disconnect the battery cables before working on the battery or any electrical components.

How do I clean the air filter on my lawn mower?

If your lawn mower is running rough or has a hard time starting, a dirty air filter could be the culprit. To clean the air filter, remove it from the mower and tap it against a hard surface to dislodge loose debris. Then, use compressed air to blow out any remaining dirt or dust. If the filter is heavily soiled, it may need to be replaced.

If you notice the air filter is clogged, it may be time to clean or replace it. A clean air filter helps ensure that the engine is getting the proper amount of air to burn fuel efficiently. If you have a washable air filter, be sure to let it dry completely before putting it back in the mower.

What if I’m using old gas?

Old gasoline can gum up the engine and prevent your lawn mower from starting. If you have old gas in your lawn mower, it’s best to drain it and refill the tank with fresh gas. If you’re not sure how old the gas is, it’s always a good idea to drain it and refill the tank with fresh gas at the beginning of each mowing season.

When draining the gas, make sure to do it in a well-ventilated area and use a container specifically designed for storing gasoline. Never pour old gas down the drain. The best way to ensure your lawn mower is using fresh gas is to only fill it with enough gas to get you through one mowing session.

What is a fouled spark plug and how do I clean it?

A fouled spark plug is a spark plug that has built up carbon deposits, oil, or other contaminants on the electrode. This prevents the spark plug from firing properly, which can prevent your lawn mower from starting. To clean a fouled spark plug, remove it from the engine and use a wire brush to clean off the carbon deposits.

If you see that the electrode is worn down or the spark plug gap is too wide, it’s best to replace the spark plug. A fouled spark plug is a common cause of a lawn mower that won’t start, so it’s always a good idea to check the spark plug as part of your troubleshooting process.

What do I do if the fuel shut-off valve is closed?

The fuel shut-off valve is typically located on the fuel line, near the fuel tank. If the fuel shut-off valve is closed, it will prevent fuel from flowing to the engine. To open the valve, simply turn the handle to the “on” position. This should allow fuel to flow to the engine and allow your mower to start.

Sometimes the valve gets stuck, which prevents it from fully opening. This can be fixed by cleaning the valve with a wire brush or by replacing the valve altogether. Before assuming this is the issue, ensure that your tank is filled with fresh fuel.

What if nothing else works?

If you’ve tried all of the troubleshooting steps above and your lawn mower still won’t start, it’s time to consult a professional. There could be a more serious issue with your mower, such as a problem with the carburetor or ignition system. It’s best to have a qualified mechanic diagnose the issue and repair it.

A professional can use specialized tools and diagnostic equipment to identify the problem. They can also help you determine if the repair is cost-effective or if it’s time to replace your lawn mower. If you’re confident in your mechanical skills, you can always consult an online manual or video tutorials to get a better understanding of the issue and potential solutions.

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