Mower Losing Power When Blades are Engaged: Causes and Fixes

Nothing is worse than when your mower loses power after attaching the blades. This issue is a common problem among lawn mower owners and can have several causes. 

Mower losing power when blades engaged issue can happen if the mower has poor throttle assembly, among several other reasons. A damaged blade or worn-out belt, clogging, worn-out pulleys, can also lead you to this problem. 

mower losing power when blades engaged

What Are The Reasons For The Mower Losing Power When Blades Engaged?

When your mower loses power when the blades are engaged, it can be attributed to various factors. Let’s explore some of the most common causes:

1. Poor Throttle Assembly:  

The lawnmower’s throttle is a part that manages the engine’s speed. The throttle controls fuel consumption and the speed of the blades while starting the engine and when mowing. 

So, if the mower loses power when the blades are attached, you should look at the throttle assembly to check if there is any problem. most of the mower has a throttle cable to control the engine speed. You better start checking from there.

If you detect any problem with your throttle settings, you should call a professional as it is a bit tricky to adjust the assembly.

2. Dull Blades:  

One of the primary reasons for power loss in a lawn mower is dull or damaged blades. When the blades are not sharp, they are unable to cut the grass effectively. 

This inefficiency puts a strain on the mower’s engine, resulting in a loss of power. People don’t check the blade condition frequently and keep mowing the same old blades over time. 


It is very obvious to fix this issue you have to either sharpen the blades or install new ones. Proper blade maintenance is very important for the longevity and performance of your mower.

But firstly, check the condition of your mower blades. If they are dull or damaged, sharpen or replace them to ensure efficient cutting and prevent power loss. 

It is suggested to match the manufacturer when it comes to blades to have the maximum performance.

3. Worn or Damaged Belts, Gears, Pulleys: 

The belts that drive the mower’s blades play a crucial role in transferring power. Gears are responsible for driving the mower’s blades. Similar to belts and gears, pulleys are vital components in the motion of the mower’s blades.

If any of them are worn or damaged, the mower may not be able to effectively deliver power to the blades. As a result, the mower can experience power loss when the blades are engaged.


Check the belts that drive the mower’s blades. If they are worn or damaged, replace them to ensure effective power transmission and prevent power loss.

If the gears responsible for driving the blades are damaged, replace them to enable proper power transfer and prevent power loss. And the same for the pulleys too.

4. Damaged Bearings or Bad Blade Spindles: 

The bearings that support the mower’s blades can also contribute to power loss. Dirt and debris can go into these bearings and, they can hinder the smooth transfer of power to the blades. 

This can result in a loss of power when the blades are engaged. In terms of spindles, they can go bad over time, causing the mower to lose power when the blades are in motion. When blade spindles are faulty, the mower may not run at full speed and may not cut the grass evenly.


Check the spindles and bearings. These bearings must be able to spin without binding or wobbling. If you notice excessive wobbling or tightness, install new spindles and bearings. 

Do lubricant these components to ensure better mowing. Setting up a regular maintenance schedule for your lawnmower will increase its lifespan and reduce the need for repairs.

5. Stuck Blade System on Blade Pulleys: 

A brake system near the blade pulleys can cause the mower to lose power when the blades are engaged. If this brake system gets stuck, it can impede the smooth operation of the blades and result in power loss.

If the brake system near the blade pulleys is causing the mower to lose power, consider rebuilding the brake system to ensure smooth operation rather than dismantling parts. 

As it is a bit hard to do you should hire a professional to fix the issue.

6. Damaged Safety Switch: 

If you have a riding mower, it has a safety switch underneath the seat. safety switch is designed to turn off the lawnmower in the event of a rollover. This prevents injury to the mower and its operator. 

If the engine shuts down when the blades are running, the reason can be a broken safety switch.

To fix this just simply change the safety switch. You have to remove the seat to access the switch. 

Tips To Revive a Mower Losing Power When Blades Engaged

In addition to the mentioned fixes, it’s essential to check the following components to revive a mower that dies when the blades are engaged:

  1. Air and Fuel Filter: Ensure that the air and fuel filters are clean and free from clogs to maintain proper airflow and fuel supply.
  2. Spark Plug: Regularly clean and inspect the spark plug to make sure it is in good condition and delivers efficient combustion.
  3. Oil Level: Check the oil level to ensure it is at the appropriate level for proper lubrication.
  4. Carburetor and Fuel Lines: Inspect the carburetor and fuel lines for any clogs or debris that may obstruct fuel flow. Clean or replace them as needed.
  5. Governor: Verify that the governor is functioning properly to regulate engine speed and prevent stalling. Ensure the governor linkage is not damaged or disconnected, as this can affect engine performance.
  6. Battery: Always check the battery if it is charged and in good condition, as a weak battery can lead to power loss. And change the water twice a year.
  7. Starter: Verify that the starter is functioning correctly, as a faulty starter can cause the issue.
  8. Ignition System: Ensure that the ignition system is in good working order to provide a consistent spark for efficient engine operation.
  9. Exhaust System: Inspect the exhaust system for any clogs or damage that may restrict airflow and impact engine performance.

These are the factors that highly maintain the quality of your mower. By checking these every time before you start mowing, you will have an even cut and the machine will last long.

So they are the basic things you should check to optimize your mower’s performance and prevent mower losing power when blades engaged.

Frequently Asked Questions [FAQs]

Why does my lawn mower speed up and slow down??

Fluctuations in speed can be caused by obstructions in the airflow, such as clogged air filters or debris in the mower’s intake. 

Why does my mower keep dying while mowing?

If your mower keeps dying while mowing, the issue may be related to spark plugs that need cleaning or replacement.

Why is my lawn mower losing power when cutting?

If your mower loses power when it is cutting grass, that means the mower has a dirty air filter on it.

Will dull blades cause a mower to stall?

There can be tons of causes that make your mower stall. And dull blade is one of the reasons.

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