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Outdoor power equipment What to do if your lawn mower won’t start

Published on April 4th, 2013 | by Jeff Linderman


What to do if your lawn mower won’t start

When you dust off your mower, push it into the springtime sun, you can nearly smell the freshly-mowed lawn. But if you’re like us, every once and a while, you’ll find that the engine won’t start.

If your lawn mower won’t start, the first thing I’d do is use an ignition/spark tester.

As the owner and operator of a residential and commercial landscaping care business for 25+ years, an ignition/spark tester was my go-to tool if an engine failed to start. With an easy-to-read terminal screen, this tester helps you troubleshoot and determine the most likely cause of the equipment’s failure to start such as a dead spark plug, a bad ignition coil or something else. It will save you a lot of time.

RepairClinic has free troubleshooting and repair help information for this lawn mower problem and many others.

The most likely cause of a lawn mower engine not starting

There are many causes for engine failure but by far, the most common cause is a faulty spark plug.

Fortunately, replacing a spark plug is simple.

Always read your lawn mower’s owner manual’s instructions for spark plug replacement. Be sure to use the exact spark plug recommended for your engine. Using an alternative spark plug can cause serious engine problems.

Here’s how to replace a lawn mower engine spark plug:

  1. Make sure the engine is cool.
  2. Remove the wire and boot from the spark plug.
  3. Use a spark plug wrench to remove the old spark plug.
  4. Install the new spark plug with care by tightening it onto the cylinder head. Be careful not to over tighten or damage the plug.
  5. Attach the spark plug wire and boot.

This Spark Plug Wrench (#1644997) enables you to more safely and efficiently remove or tighten a spark plug. We often give this tool as gifts to family and friends, as it comes in handy for anyone who owns a lawn mower, snowblower or other small engine. Check out our other favorite tools for DIYers.

Here’s our helpful video on how to use a spark plug wrench:

How to avoid engine failure in the future

Replace the spark plug at least once per season, even if it appears to be working. Over time, a spark plug’s performance will degrade due to carbon build-up and a weakened electrode. This dramatically increases emissions, reduces engine performance and requires the engine to use more fuel.

Engine tune-up kitEvery spring, I purchase tune-up kits packed with a spark plug, oil, filter, fuel stabilizer and other essential maintenance products as recommended by the manufacturers specifically for my engine models. It takes the hassle out of looking up each individual product.

A spring engine tune-up will improve engine performance, reduce emissions and extend the life of equipment. Save yourself the hassle of finding tune-up essentials like motor oil, air filters, spark plug and fuel stabilizer individually. A tune-up kit designed for your engine includes everything you need. Enter your engine model number at to find the kit designed specifically for your model. All tune-up kits are on sale through May 31, 2013.

Other helpful information

7 simple ways to make lawn mowers run like new

11 easy, money-saving steps to prep your snowblower for storage

Lawn mower maintenance tips

How a lawn mower works

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Since 1999, three and a half million people have purchased replacements parts and accessories from RepairClinic and saved more than $260 million in repair costs by fixing appliances, lawn equipment, power tools, and heating & cooling equipment on their own. From the beginning, RepairClinic has provided free troubleshooting and how-to resources on its website.

The company’s 2,000+ free how-to repair and how-it-works videos on its YouTube channel have been viewed more than 41 million times.

RepairClinic’s free, advanced online repair help system empowers do-it-yourselfers to fix common problems associated with home appliances, lawn equipment, power tools and heating & cooling equipment. DIYers can enter a model number to choose from a list of common symptoms for that particular model, troubleshoot and watch award-winning, expertly-produced videos to learn the most likely causes and conditions and purchase the correct part. stocks more than one million parts and accessories for 160 brands of lawn mowers, small engines, snowblowers, string trimmers, furnaces, air conditioners, air handlers, heat pumps, washing machines, dryers, dishwashers, vacuum cleaners, power tools and many other products.

Since 1999, the company has served more than three million customers including homeowners, first-time and beginner DIYers, advanced DIYers, appliance repair professionals, small engine repair shops and landscaping and lawn care business owners. RepairClinic orders are backed by a 365 Days. Period.® return policy that enables customers to return any part. Of the more than one million parts available on the website, 95 percent of parts ordered are in stock and guaranteed to ship the same business day. RepairClinic ships within the United States, U.S. territories and military bases and Canada.

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About the Author

Jeff Linderman is’s in-house outdoor power equipment and landscaping expert. For 25 years, Jeff owned and operated a successful commercial and residential landscaping business. He couldn’t afford the extensive downtime that came when he brought his equipment to be repaired at overloaded small engine repair shops. Instead, Jeff learned how to complete the repairs on his own. This interest in outdoor power equipment grew as Jeff completed extensive manufacturer training. Today, Jeff is a Briggs & Stratton® Master Service Technician, Kohler® Engines Expert Technician and a Kawasaki® Service Technician for Engines and Power Products. He has a B.A. in criminal justice from Michigan State University. Jeff worked for 25 years as a sergeant in the Wayne County Sheriff’s Department while he operated his landscaping business. He’s an avid fisherman and lives in the metro-Detroit area.

21 Responses to What to do if your lawn mower won’t start

  1. Marsha Fleming says:

    Thanks for the info!! Is there a way to store a riding lawnmower over the winter so that it works in the spring? It seems to always be dead in the spring then I have to get a new one:(

  2. Hi Marsha, thanks for the note. I suggest that you remove the battery from the equipment and store it in your basement or another area in which the temperature is consistent and not freezing. Then in the spring, I would I use a battery charger and re-charge the battery before re-installing it. Make sure the battery cables are free of corrosion and secured tightly. Thanks for the question!

  3. K Frey says:

    Your site is great, but the info on replacing spark plugs is not acurate. In 25 years of working on small engines, the spark plug is the problem in less than 1 out of 100 small engines. It is almost always a carburetor or a jet problem caused by leaving fuel in the engine for too long without a stabilizer. Your info is stating that replacing a spark plug will fix most starting problems with small engines…you even have it in bold type. This simply just isn’t true & you are telling people to buy something that just won’t fix the problem 99% of the time.

    • Hi, K Frey,

      Thanks for reading and for your comment. We’re happy to have you reading this blog, especially since you bring 25 years of small engine repair expertise. That’s great!

      The advice in this post is: “If your lawn mower won’t start, the first thing I’d do is use an ignition/spark tester.” We hear from people every day who are not aware that they can test this. Very frequently, after testing, they discover a spark plug or ignition coil replacement is the solution. We also direct them to our free troubleshooting and repair help information which will provide engine model-specific troubleshooting information. You are right that stale fuel can cause engine failure. That’s definitely a common cause. However, in our experience, a faulty spark plug is more commonly the cause and we feel it’s important to inform our readers and customers about this first step. In the listed related posts, we explain the importance of proper engine care and using fuel stabilizer, for the reasons you state. Thanks for the feedback!

  4. Richard Tangeman says:

    I have a strange problem with my 6 year old Toro self-propelled lawn mower. It starts just fine. I watch the quality of fuel and replace the spark plug and air filter every fall before storage in a warm basement. The problem I am having is getting it to restart after it is hot from mowing a while. I have to shut it down occasionally to pick up or do some other miscellaneous clean up in the yard. When I go back to start it after just a few minutes, it won’t start. if I let it sit for 15 – 20 minutes and let it cool down it will start again as before. What could be the problem?

  5. Hi Richard,

    Thank you for the comment! Have you checked out our Repair Help on this topic?

    You’ll also find helpful information a reliable small engine repair forum. We wish you a fast and successful repair of your Toro. Thanks for reading!

  6. Daniel says:

    When I had a husqvarna lawn mower a few years ago, this problem was very common. Now I have a greenwoks mowers and it works fine. I have been using it for a year and there were no problems with the ignition.

  7. Trent says:

    My riding mower just stopped its a craftsman 18 horse power it’s been running fine

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  10. Bob Grier says:

    Thanks for the tips I’ve been looking for a way to restore my old Toro which gave up on me probably due to overuse.

  11. Louie sharpe says:

    Nice tips. I know most of them, but everyone don’t know about these tips. People should be aware of these tips.

  12. Joel says:

    I also switched to greenwoks mowers cause they offered them with a high discount so I gave them a try and never regretted it. But thank your for this resource because when my mower won’t start I now know what to do!

  13. Hi Jeff, thanks for the helpful information in this post and in the videos. Taking care of lawn equipment and performing maintenance is a key to ensure your getting the most return for you money invested in the equipment.

  14. Mike Mannion says:

    I was on my rider mower (craftsman 2010) when It suddenly made a grinding sound and turned off. A small amount of gray smoke. When I tried to turn it over the engine would not move. I tried to manually turn the engine but it wouldn’t budge. I just changed the oil a few weeks ago. It seems like the engine has seized up but not sure what happened. Any thoughts?

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