Lawn Mower Surging Try These 6 Steps

Have you ever experienced a lawn mower that won’t start, runs inconsistently, or surges? If so, you are not alone. Lawn mower surging is a common problem that can be difficult to diagnose and repair. Fortunately, there are some simple steps you can take to troubleshoot and fix this issue. In this blog post, we will discuss 6 steps you can take to get your lawn mower back up and running smoothly. Read on to find out what to do if you encounter lawn mower surging.

1) Check the Fuel

Check the Fuel

If your lawn mower is surging, the first thing you should check is the fuel. Make sure that the fuel tank is filled with fresh gas and there are no signs of water or contamination. If the fuel has been sitting for a while, it can begin to break down and become less effective in running your lawn mower. Additionally, old fuel can cause clogging in your engine, which will result in surging. To avoid this, make sure you are using fresh fuel in your mower.

2) Check the Air Filter

Check the Air Filter

One of the most common causes of lawn mower surging is a clogged air filter. The air filter helps ensure that your mower’s engine is getting the correct amount of air, and when it gets clogged, the engine can’t get enough air and starts to surge. To check the air filter, locate it under the engine hood and remove it. Inspect it for any dirt, dust, or debris that may have built up.

If the filter is dirty, replace it with a new one. If not, you can try cleaning it with warm soapy water or an air compressor. Once your air filter is replaced or cleaned, you should be able to notice a difference in how your lawn mower runs.

3) Check the Spark Plug

Check the Spark Plug

If your lawn mower is surging, the first thing to check is the spark plug. A dirty or faulty spark plug can cause your lawn mower to surge or cut out while you’re using it. The most common sign of a problem is if your engine starts and then suddenly dies after running for a few seconds.

To check the spark plug, first, make sure your lawn mower is turned off. Then, remove the spark plug using a spark plug wrench. Once you have removed the plug, inspect it to see if it looks damage or dirty. If so, it’s time to replace it. You can purchase new spark plugs from any local hardware store or online.

When replacing the spark plug, make sure to use the correct size and type for your particular lawn mower model. Also, be sure to tighten it securely with a spark plug wrench. Finally, re-install the spark plug and try starting up your lawn mower again.

4) Check “Clogged” Lawnmower Gas Cap

Check “Clogged” Lawnmower Gas Cap

If your lawn mower is surging, one of the first places you should look is the gas cap. It’s possible that the gas cap is clogged or has a small hole in it, which can cause the fuel to escape and leave a vacuum inside the tank. This vacuum can cause the fuel-air mixture to be off balance and cause the engine to surge.

Fortunately, checking the gas cap for a clog or hole is easy to do. Simply remove the gas cap from the tank and inspect it for any signs of blockage or damage. If there’s a hole in the cap, replace it with a new one. If it’s simply clogged, clear away any debris that could be blocking the flow of fuel.

Once you’ve checked the gas cap, reinstall it and make sure it’s tightly closed. Start up your mower and test it out. If the problem persists, you may need to try other steps to get your mower running smoothly again.

5) Check Vacuum Line Leak

Check Vacuum Line Leak

If your lawn mower is surging, it could be due to a vacuum line leak. This can be identified by inspecting the vacuum lines connected to your lawn mower engine. Check for any loose connections or cracks in the lines, as well as any debris that may have built up in the area. If there are any leaks, they will need to be sealed or replaced. Make sure to take care when replacing the lines, as any mistake could result in further damage to your lawn mower engine.

6) Check Dirty Carburetor

Check Dirty Carburetor

It’s frustrating when your lawn mower starts surging, but luckily this is often a fixable issue. One of the first steps in troubleshooting lawn mower surging is to check the carburetor. A dirty carburetor can cause the engine to run erratically or not at all.

The best way to clean a carburetor is to take it off the lawn mower and spray it down with a carburetor cleaner. Once you’ve cleaned the carburetor, be sure to put it back in its place and reattach the screws. If the carburetor was clogged, the surging should cease. If it isn’t fixed, move on to the next step.

How To Repair Dirty Lawnmower Carburetor

It’s summertime, and your lawn mower is ready to help you keep your lawn looking its best. But if your lawn mower is surging or running erratically, it may be time to check the carburetor. The carburetor is a crucial part of your engine that mixes air and fuel together in order to create combustion. If the carburetor is dirty or clogged, it can cause the lawn mower to run rough or even shut off completely.

Fortunately, there are a few simple steps you can take to clean and repair your dirty lawnmower carburetor and get it running smoothly again. Here’s how:

  • Disconnect the spark plug wire from the spark plug. This will prevent the engine from starting up while you’re working on it.
  • Remove the air filter and set it aside.
  • Use a flat-head screwdriver to loosen the four screws securing the carburetor cover. Then, carefully lift off the cover and set it aside.
  • Locate the main jet and idle jet located inside the carburetor and use a small brush or cotton swab to clean away any dirt or debris that has accumulated in them.
  • Take a can of compressed air and blow through the jets to ensure they’re clear of any obstruction.
  • Reattach the carburetor cover, air filter, and spark plug wire and start your mower again. It should now be running smoothly.

By following these steps, you can easily repair a dirty lawnmower carburetor and get your mower running like new again. If the problem persists after trying these steps, you may need to take your lawn mower to a professional for more extensive repairs.


If your lawn mower is experiencing surging, it can be a frustrating and confusing experience. By following the steps outlined in this blog post, you can help identify the root cause of the problem and take the necessary steps to solve it. Additionally, understanding the basics of lawn mower operation can help you avoid future issues.

If the surging persists after trying these steps, it is important to consult a qualified lawn mower repair professional. They will be able to diagnose the issue more accurately and provide an appropriate solution.

In conclusion, lawn mower surging can be a hassle to deal with but following these 6 steps can help you identify and solve the problem. Learning more about lawn mower operation and maintenance can also help you prevent future issues. Finally, if the problem persists or is too complex, don’t hesitate to seek out a qualified lawn mower repair professional.


Q. I think my lawn mower is surging, what do I do?

A: Make sure the engine is off, then place your finger on the spark plug wire and pull it out for 10 seconds. If the engine doesn’t start back up, you might need a new spark plug wire or a new coil.

If this fixes the problem, try replacing the parts if they are more than three years old. If not then it might be time to replace your lawn mower.

Q. What should I do if my lawn mower does start again but surges later in the day?

A: When a surge happens after running for about an hour, your carburetor may have flooded with gasoline. In that case, turn the fuel valve all the way off and then wait ten minutes before restarting.

Q. Why Does a Lawnmower Engine Backfire?

A. Even though it sounds terrible – an engine backfire does not typically damage a small engine.  It can, however, be a sign that one of the following issues is occurring:

  • Using gasoline with too much alcohol – (Use maximum recommended 10% Ethanol)
  • Turning the engine speed down too quickly (lower engine throttle slower)
  • High engine temperatures (mow during cooler temperatures – or mow in two shifts – if possible)
  • Lack of adequate air (dirty filter)
  • The carburetor is running lean (adjust carburetor for proper air/gas mix)

Q. My lawnmower’s been surging for two months now, what should I do?

A. First, check to make sure there’s gas in the tank. Then drain some gas into a canister or empty container by turning off the fuel valve and pulling out the plug wire.

Let the carburetor sit dry overnight (but don’t forget to put oil in before using it). Next morning, pour some fresh gas into the tank and give it another go; hopefully that clears up any clogs!

References & Additional Resources

Last Updated on December 19, 2022

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Mark Wright
Mark Wright
Mark Wright is the author and editor for Printerchief, where he brings his expertise in research and the English language to life in the world of technology journalism. When he's not immersed in the world of print, he loves exploring the outdoors in Michigan and Arizona - taking long hikes, fishing and cycling along the way. Andrew is a big reader and likes to take on DIY projects around the home and garden. With a love for the great outdoors and a sharp eye for detail, Andrew has managed to bring both a sense of adventure and enthusiasm to all his work.


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