Why Engine Dies When PTO Is Engaged? Reasons And Solutions Explained

PTOs are used to transfer power from the engine to a tool or attachment. When the engine is not running at its optimal level, it can cause the mower to have problems when the PTO is engaged.

If you have a mower that is dying when the PTO (Power Take-Off) is engaged, it indicates a problem with the engine. The reasons include – a worn-out spark plug, a clogged air filter, a blocked fuel line, or even a faulty PTO switch.

This article will discuss more reasons in details and how to fix each issue when the engine dies when PTO is engaged. So tag along till the end!

Engine Dies When PTO Is Engaged

What Causes A Mower Engine Dies When Pto Is Engaged Engaged? (Fixes Added)

There can be several reasons why a lawn mower engine may die when the PTO (Power Take-Off) is engaged. These are discussed below:

1. Mower Blades Engagement Issue

The most common cause is that the mower blades are not properly engaged. This means that the blades are not securely connected to the PTO shaft. This causes the engine not receive necessary power to keep running.

Fix: Blade Adjustments

Make sure the blade you are using in the mower is appropriate for the engine. Make sure it has proper connection with the engine.

Here is a table containing proper mower blade size for engine:

Engine Capacity (cc)Blade Length (in)
50 – 75 cc18 – 20 inches 
76 – 100 cc          20 – 22 inches            
100 – 125 cc         22 – 24 inches         
126 – 150 cc         24 – 26 inches          
151 – 175 cc   26 – 28 inches           
176 – 200 cc        28 – 30 inches            
201 – 225 cc        30 – 32 inches           
226 – 250 cc       32 – 34 inches         
251 – 275 cc        34 – 36 inches          
276 – 300 cc      36 – 38 inches         

2. Safety Switch

It’s possible that the seat switch is bad, or that there’s a loose plug or a bad wire.

Fix: Replace  Seat Safety Switch

The seat safety switch can be damaged or stuck. Replace the switch if cleaning does not get rid of the stuck switch.

3. Clogged Air/Fuel Filter

A dirty air or fuel filter can restrict air or fuel flow to the engine respectively. This might cause the engine to die when the PTO is engaged.

Fix: Replace Dirty Filters and Lines

Replace the dirty fuel filter and air filter. Also replace any damaged fuel line. Clean the carbon buildup in any fuel line.

4. Bad PTO Clutch and Worn Out PTO Belt

The PTO clutch can wear out or become damaged over time. This may cause it to fail to engage properly. As a result, the engine to stalls when the PTO is engaged.

Besides, a worn-out or damaged PTO belt can cause the engine to die when the PTO is engaged. The belt can become worn and stretch over time. This results in a loose connection between the engine and the blades.

Fix: Replace Bad PTO Components

When the problem occurs, here are the PTO components to troubleshoot:

  • Inspect the PTO clutch cable to ensure that it is in good condition and connected properly. If it is worn out or loose, then replace it.
  • Inspect the PTO clutch to make sure it is not broken or damaged. If it needs to be replaced, then do so.
  • Clean the PTO clutch to make sure it is free of dirt and debris. This will help ensure that it is engaging properly.
  • Inspect the PTO engagement lever to make sure it is working properly. If it is not, then replace it.
  • Inspect the PTO switch to make sure it is working properly. If it is not, then replace it.

5. Problem with the Battery

Additionally, if the battery is low or the charging system is faulty, the PTO clutch will stall the engine.


Check the battery wiring, charge and if needed, replace with a new battery.


Other causes of engine failure when the PTO is engaged include a faulty spark plug, a dirty carburetor, a clogged fuel line or a PTO switch in ‘on’ position.

How to Diagnose a Mower Engine That Dies When the PTO Is Engaged

It can be confusing as to how to get started with troubleshooting when the mower engine dies when PTO is engaged. However, look at the step by step process below:

Step 1:

Check the spark plug. If the spark plug is wet or fouled, replace it and try to restart the engine. Make sure the spark plug has secured connection.

Step 2:

Check the air filter. If the air filter is clogged or dirty, replace it.

Step 3:

Check the fuel filter. If the fuel filter is plugged or dirty, replace it and check the fuel line for any blockages.

Step 4:

Check the carburetor. Make sure it is properly adjusted and that all of the screws are tight. Check for any signs of dirt or debris.

Step 5:

Check the ignition system. Make sure the spark plug wires are connected properly, and that the ignition switch is working properly.

Step 6:

Check the PTO switch. Make sure the switch isn’t stuck in the “on” position. If necessary, replace the switch.

Step 7:

Check the PTO clutch. Make sure it is functioning properly and that all the connections are tight.

Note: If these steps do not resolve the problem, it is likely that the engine itself is malfunctioning and needs to be serviced or replaced.

Related Post: How To Fix Lawn Mower Engine Dies When Clutch Released?

Easy Fixes for a Mower Engine Dying

Not just when PTO is engaged, but a mower engine dying is a common complaint. In addition to the discussed solutions, the following can fix the mower engine dying:

  • Check the fuel – Make sure the fuel is fresh and has the correct mix of oil and gasoline.
  • Change the spark plug – A worn spark plug can cause the engine to misfire and die.
  • Clean the carburetor – A clogged carburetor can prevent the engine from getting enough fuel, causing it to die.
  • Adjust the idle speed – An incorrect idle speed can cause the engine to die when it is not running at full throttle.
  • Check the compression – Low compression can cause the engine to die.
  • Check the governor – An incorrectly set governor can cause the engine to die.
  • Check for vacuum leaks – Vacuum leaks can cause the engine to die.

Going over these things makes sure you don’t leave any stone unturned to fix your dying engine. But if the problem persists, a professional intervention becomes a must.

 Frequently Asked Questions (FAQs)

How do I test my PTO switch?

The most accurate way to test a PTO switch is to use a multimeter. If the switch is functioning properly, the multimeter should read a closed circuit. If it reads an open circuit, the switch will need to be replaced.

What causes PTO failure?

PTO failure can be caused by a number of factors, including worn or faulty components, incorrect installation, incorrect operating speed, inadequate lubrication, and excessive vibration. In addition, mechanical damage, such as a bent shaft, can cause PTO failure.

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