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If your Exmark mower loses power when the blades are engaged, it might be due to a dirty underside, dull blades, seized-up pulley, defective spark plug, and clogged air filter.

In this article, I share 13 common reasons why your Exmark mower loses power when the blades are engaged and practical troubleshooting steps you can take to diagnose and fix this issue.

Contents show

Reasons Why Your Exmark Mower Loses Power When Blades Are Engaged

Some of the reasons why your zero-turn may lose power when blades are engaged may include:

Dull blade
Worn out blade spindle bearings
Faulty spark plug
Clogged fuel filter
Dirty carburetor
Dirty underside
Loose/worn mower belt

Tools You May Need for This Job

Torque wrench
Safety glasses
Socket wrench
Work gloves.
Cordless Impact Gun (Optional)
Compressed Air
Ratchet

Exmark Mower Loses Power When Blades Are Engaged: Possible Causes and Fixes

1. Dull Blade

Your Exmark lawn mower can lose power if you are mowing with dull mower blades.

This can affect the functionality of the mower because the blades may need to work harder to mow grass and may cause the engine to lose power.

Diagnosis

Check the blades to see if they are dull.

Fix

Sharpen or replace them if necessary.

How To Remove and Replace The Blades of Your Exmark Mower

Here are some tips on how to remove the blades of your Exmark mower:

Step One: Gather the Required Tools

Gather the required tools for your blade removal. You need to get tools such as a cordless impact gun, safety glasses, torque wrench, ratchet and work gloves.

Step Two: Take Off Your Spark Plug Boot

It is important to remove the spark plug boot and ignition key to prevent your mowing machine from starting and the cutting deck from engaging.

Furthermore, wear safety glasses and gloves to offer protection while working on your mower.

Step Three: Remove and Reinstall the Blades

Make use of the ratchet and socket to take off the bolt that secures the blade to the spindle. You can also use a cordless impact gun if it does not come off easily.

You can also use a block of wood to detach the stubborn bolt.

Put the block wood over the bolt and hit the block with a hammer to loosen and shock your bolt. This will enable you to turn your bolt and detach it.

Take off the blade, bolt and washer. Some Exmark mowing machines come with a splined housing that is located in the center hole that requires removal when you want to detach the bolt.

Re-install the sharpened or new blades in the opposite order that you took them off.

Use your torque wrench to secure the bolt. Torque the bolt to 50-60 ft-lb. Avoid using an impact gun because you can over tighten the bolt and damage the mower’s spindle.

2. Worn Out Blade Spindle Bearings

Worn-out blade spindle bearings can be a reason why your Exmark mower may lose power when blades are engaged.

The bearings enable the blades to freely spin on their axis. If it is worn out, it can cause friction and may make your mowing machine lose power.

Diagnosis

Examine if the blades can freely spin on their axis. If not, it means that the bearings in the blade spindles are worn out.

Fix

Replace worn-out blade spindle bearings.

3. Clogged Muffler

The function of the muffler is to expel the burned gas and other vapors. If it is blocked by grass, dirt, and other debris, it can cause your mower to lose power.

Diagnosis

Check the muffler for debris, dirt, and other fluids.
If you notice a colored smoke that comes out of your zero-turn mowing machine, then there is a high chance that the muffler is clogged.

Fix

Replace the clogged muffler for a new one.

4. Clogged Fuel Filter

In some cases, dirt and the substances left behind by the running old gas can cause your fuel filter to become clogged.

If the fuel filter is clogged, it can cause a fuel filter, resulting in your mower losing power when the blades are engaged.

This is why it is important to replace the fuel filter yearly when performing your routine maintenance tasks.

Diagnosis

Check the fuel filter for signs of dirt and other debris left behind by old gas.

Fix

Replace the old filter with a new one.

5. Clogged Fuel Lines on Your Exmark Mower

Clogged fuel lines can also be one of the reasons why your mower can lose power when the blades are engaged.

Dirt and other substances can block the fuel lines which can affect the performance of your mower.

Diagnosis

Check for clogs in fuel lines by starting and stopping the flow of fuel with the use of a fuel shut-off valve that is situated beneath the fuel tank. Make sure that the fuel flow is stopped.
Take off the furthest end of your gas tank of one section of the fuel line and put it in a container. Ensure that you start the flow to inspect signs of blockages.
You can also continue to inspect the other sections of your mower’s fuel line.

Fix

When you discover the blocked line, take off this section of the line and spray your carburetor cleaner into the line to loosen up clogs.
Furthermore, blow compressed air through the line to clear further blockages. If you detect that the line is dry, cracked or you cannot take off the blockages, ensure that you change the old fuel line with a new one

6. Dirty Carburetor

The carburetor is an important component of your Exmark mower. It allows the right combination of air that will go into the engine cylinder so that combustion can occur.

The dirt and other substances caused by old fuel can cause your carburetor from providing the fuel needed to operate. If this happens, it can cause your mowing machine to lose power.

Diagnosis

Inspect the carburetor for dirt and other substances left behind by old gas.

Fix

Clean the carburetor or replace it if it is not in a good condition.

7. Dirty Underside

A dirty underside might be one of the reasons why your Exmark mower may lose power when the blades are engaged.

This issue is common with Husqvarna Exmark mowers. Whenever the blade is engaged, the underside rotates on a crankshaft to mow the grass.

The mower engine can shut off if there is an interference in this rotation.

Diagnosis

Inspect the connection of the crankshaft to see if it rotates freely. If the crankshaft’s connection does not rotate freely, it indicates that the mower’s underside is dirty.

Fix

Clean the blade so that it will be free of debris, dirt, and grass.

8. Loose or Worn Mower Belt

When mower belts are not properly routed, they will cause issues when the blades are engaged.

In addition, a loose belt can also slip off the pulleys, causing the mower to lose power.

Diagnosis

Examine the belt for wear, cracks, breaks or slippage.

Fix

Replace the belt if it is in a bad condition.

9. Bad Pulleys

The mower belt drives the pulleys, which in turn moves spindles.

If the pulleys cannot turn freely, they would cause the engine to lose power. This will affect the operation of your Exmark mower.

Diagnosis

Check pulleys if they are moving freely. If not, it indicates that the pulleys are bad.

Fix

Replace the pulley if it is sticky or damaged.

10. Dirty Air Filter

It is also important to check the air filter if your Exmark mower is losing power.

The mower engine requires air to run and when it no longer gets the air it requires, the engine may lose power.

Diagnosis

Take off the air filter from the air filter housing and check for dirt on it

Fix

Clean or replace the air filter if it is in bad condition.

11. Faulty Spark Plug

For air and gas to be ignited, the mower’s spark plug must be in a good condition and correctly adjusted.

Over time, it may wear out and it will no longer have enough power to ignite gas and air This can make the zero-turn tp lose power when blades are engaged.

Diagnosis

Use a socket wrench to remove the spark plug.
Clean the spark plug with a wire brush.
If the firing end is covered with carbon, it means that the spark plug needs to be changed.

Fix

Replace the faulty spark plug with a new one.

12. Seized Up Pulley or Spindle

This is one of the causes why your Exmark mower may lose power when the blades are engaged.

If the spindle gets seized up, it requires that you replace it or else it can affect the performance of your mower.

Diagnosis

Inspect the mower to check if the pulley or spindle is seized. If this happens, it indicates that it needs replacement.

Fix

Replace the seized pulley or spindle with a new one.

13. Dysfunctional Governor

The governor of your Exmark mowing machine may malfunction as a result of obstructions caused by dirt and other debris, causing it to lose power when the blades are engaged.

Diagnosis

Check the mower’s governor for signs of obstructions caused by dirt.

Fix

Replace the governor of your Exmark mower.

Conclusion

It is important to note that this is one of the most common Exmark mower problems. If you notice that your Exmark mower loses power when the blades are engaged, the first step to take is to figure out what is causing it.

Some of the possible causes include a worn belt, dysfunctional governor, faulty spark plugs, clogged air filter and clogged fuel filter/lines.

Follow our troubleshooting tips to identify and fix these issues. If you still can’t find the solution to this problem, it is best to contact a technician to help check out your Exmark mowing machine.