5 Reasons Why Your Lawn Mower is Revving Too High

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Are you hearing an unusually high revving sound coming from your lawn mower? If so, it’s likely that your lawn mower’s RPM is too high. High RPM can lead to several issues, including poor fuel economy, reduced engine life, and safety hazards. In this article, I’ll go over the reasons why your lawn mower is revving too high and how to address the problem. I’ll also highlight any specific causes and solutions related to ride-on mowers.

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Why is My Lawn Mower Revving High? (Overview)

The primary reason why your lawn mower might be revving too high is that the engine is receiving too much fuel or air. This can be due to various factors, including a clogged air filter, a malfunctioning carburetor, or an issue with the governor. These problems can result in high RPM, which can lead to overheating and engine damage. 

5 Common Reasons Your Lawn Mower RPM is Too High

Let’s take a closer look at some of the most common reasons why your lawn mower is revving too high:

Clogged Air Filter 

A dirty air filter can restrict airflow to the engine, causing it to run rich and rev too high. Therefore, you’ll need to either clean or replace the air filter to improve airflow and reduce RPM.

Carburetor Issues

The carburetor is responsible for mixing fuel and air in the correct proportions before it enters the engine. If the carburetor is dirty or clogged, it can cause an over-rich mixture, leading to high RPM. You may need to clean, adjust or replace the carburetor to fix the problem.

Governor Issues

The governor is a mechanism that regulates engine speed. If the governor spring is bad or the governor isn’t adjusted correctly, it can cause the engine to rev too high. You may need to adjust or replace the governor to fix the issue.

Throttle Cable Issues

A stuck or damaged throttle cable can cause the engine to rev too high. Check the cable for any signs of wear or damage. You may need to either clean or replace the cable.

Fuel Issues

A clogged fuel filter or a bad fuel pump can restrict fuel flow to the engine, causing it to run lean and rev too high. So, take a look inside the fuel filter if your particular filter is transparent, and look for any dirt. If your lawn mower doesn’t have a clear fuel filter, you’ll need to simply replace it.

Check out these articles to keep your fuel system running smoothly:

How to Fix a Lawn Mower That is Over Revving

Now that you have looked through some of the common causes why your lawn mower might be revving high, it’s time to take a look at the repairs. Here are all the steps and tools you’ll need to resolve the revving issue and get your lawn mower running like normal.

 Cleaning the Air Filter

  1. First, remove the air filter cover from the lawn mower. Depending on your lawn mower model, you may need a screwdriver or a wrench to remove the cover.
  2. Once the cover is removed, take out the air filter. Check the air filter for damage, such as holes or tears. If the filter is damaged, it’s better to replace it than to try and clean it.
  3. Use an air compressor to clean the air filter. Hold the air filter in one hand and direct the air stream at it with the other hand. Make sure to blow air from both sides of the filter to remove all the dirt and debris.
  4. If the filter is really dirty, you may need to repeat the process a few times until the filter is completely clean.
  5. Once the filter is clean, reinsert it into the lawn mower and secure the cover back in place.
  6. Finally, start the lawn mower and make sure it’s running smoothly.

What You’ll Need to Clean a Lawn Mower Air Filter

  1. Air Compressor with Air Gun
  2. Compressed Air Wand Attachment for Air Compressor
  3. Safety Glasses
  4. Gloves
  5. Screwdriver Set
  6. New Air Filter (if the old one needs to be replaced)

Cleaning a Lawn Mower Carburetor With Cleaning Spray

  1. Turn off the lawn mower and allow the engine to cool down. 
  2. Disconnect the spark plug wire from the spark plug to prevent any accidental start-ups while you are working on the carburetor.
  3. Locate the carburetor. It is usually found near the engine and has a fuel line and a choke lever connected to it.
  4. Use a screwdriver or wrench to remove the screws holding the carburetor cover in place. Carefully remove the cover and set it aside.
  5. Locate the small metal tubes or jets inside the carburetor. Spray the carburetor cleaning spray directly onto these areas, making sure to cover all visible parts.
  6. Let the carburetor cleaner soak in for a few minutes. This will help to dissolve any built-up deposits or debris.
  7. Use a toothbrush or a small brush to scrub away any remaining grime or dirt from the carburetor.
  8. Reassemble the carburetor cover and tighten the screws back in place.
  9. Reconnect the spark plug wire to the spark plug.
  10. Start the lawn mower and let it run for a few minutes. This will help to ensure that the carburetor is working correctly and that the engine is running smoothly.

By following these steps, you should be able to clean your lawn mower carburetor using a carburetor cleaning spray. However, if you are still experiencing problems with your lawn mower after cleaning the carburetor, you may need to remove the carburetor from the lawn mower completely to carry out a more thorough clean.

For a more in-depth guide and other cleaning methods, check out my article on how to clean a lawn mower carburetor.

What You’ll Need to Clean a Lawn Mower Carburetor

Repairing a Lawn Mower Governor

  1. Turn off the lawn mower and disconnect the spark plug wire to prevent accidental start-up.
  2. Locate the governor system. It is usually located near the carburetor or the engine block and is connected to the throttle linkage.
  3. Inspect the governor linkage for any damage, rust, or wear. If it is damaged, replace it with a new one.
  4. Check the governor spring to see if it’s stretched or broken. If it’s damaged, replace it with a new one.
  5. Adjust the governor tension by loosening the screw that holds the governor arm and sliding the governor lever until the throttle plate is closed. Then, re-tighten the screw.
  6. Start the lawn mower and observe the engine speed. If it’s still running too fast, you may need to adjust the governor tension more until the engine runs smoothly.

What You’ll Need to Repair a Lawn Mower Governor

Repairing a Lawn Mower Throttle Cable

  1. Remove the air filter and housing: Before you can access the throttle cable, you need to remove the air filter and housing. Typically, you can unscrew or unclip the housing to remove it.
  2. Locate the throttle cable: The throttle cable connects the throttle lever to the carburetor. You should be able to find it easily once you remove the housing.
  3. Inspect the cable: Check the condition of the cable to see if there are any visible signs of damage or wear. If the cable is frayed, rusty, or broken, it needs to be replaced. If the cable is still intact, proceed to the next step.
  4. Adjust the cable tension: If the cable tension is too loose or too tight, it can cause issues with the throttle. To adjust the tension, locate the adjustment screw or knob on the carburetor and turn it until the cable is at the correct tension. Refer to your owner’s manual for the correct tension specifications.
  5. Lubricate the cable: Use a lubricant such as WD-40 to lubricate the cable. Apply the lubricant to the cable and work the throttle lever back and forth to distribute it evenly. This will help prevent the cable from binding or sticking.
  6. Reassemble the housing and air filter: Once you have adjusted and lubricated the cable, reassemble the air filter and housing.
  7. Test the mower: Start the mower and test the throttle to ensure it is working properly. If the throttle is still not working correctly, there may be other underlying issues that need to be addressed.

What You’ll Need to Repair a Lawn Mower Throttle Cable

Replacing a Lawn Mower Fuel Filter

  1. Turn off the lawn mower and disconnect the spark plug to avoid any accidents.
  2. Locate the fuel filter on the fuel line, which is usually located near the carburetor or gas tank.
  3. Use pliers to clamp the fuel line on each side of the fuel filter to prevent fuel from spilling out.
  4. Use a flathead screwdriver to loosen the clamps securing the fuel filter to the fuel line.
  5. Slide the fuel filter off of the fuel line and dispose of it properly.
  6. Insert the new fuel filter onto the fuel line in the correct orientation, with the arrow on the fuel filter pointing towards the carburetor.
  7. Tighten the clamps securely with a flathead screwdriver.
  8. Remove the pliers from the fuel line.
  9. Reconnect the spark plug.
  10. Turn on the lawn mower and check for any fuel leaks.

For a more in-depth guide on changing in-line and in-pipe filters, check out my article on how to replace a lawn mower fuel filter.

What You’ll Need to Replace a Lawn Mower Fuel Filter

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