6 Reasons Your Lawn Mower Engine Dies When PTO Is Engaged and How To Fix

An engine is the primary source of power for your lawn mower. If it fails, your lawn mower may be slower than usual or may not start at all. If your lawn mower engine dies when PTO is engaged, there could be multiple issues that need immediate action. Your mower’s engine fails when PTO is engaged because of fuel issues, PTO clutch issues, battery issues, air filter issues, or a poor charging system.

Luckily, most problems are simple, and you can readily diagnose and fix them. Below we explore the main reasons why your engine stops and quick fixes.

Reason 1: Fuel Issues

Your lawn mower needs oil for effective operation. However, multiple fuel issues may make the PTO clutch die shortly after damage.

Here are some of them:

No fuel – Your lawn mower will not start if there is no engine to run the fuel. 

Old fuel – Oil breaks down with time and becomes less or not effective at all. The oil might be too old to keep your engine running despite engaging the PTO clutch if you haven’t used your lawn mower for years.

Clogged fuel pipe or cap – Clogging happens when the oil valve is very old and ineffective or when some grass and debris have filled it, restricting the free flow of fuel. In such cases, the passage of oil is limited, which may be why your lawn mower engine dies when PTO is engaged.


Here is how to prevent the fuel issues from affecting the smooth operation of your lawn mower:

  • Check the fuel tank if its empty and refill it with the correct fuel or gas
  • Drain any old fuel if you have not been using your lawn mower and refill with a newer one
  • Remove any clogs or deposits on fuel valves that may be interfering with the free flow of fuel
  • Clean the fuel filter or replace

Lastly, ensure you use the proper oil, fuel or gas for your lawn mower engine type.

Reason 2: PTO Clutch Issues

A faulty clutch may be the reason why your lawn mower engine dies when PTO is engaged.

If there’s a clutch issue, the engine might not start or die shortly, and the blades may not begin turning.

The main clutch issues happen when the clutch has mechanical damage or does not get the correct voltage.

Common signs of a faulty PTO clutch include:

  • Noisy clutch when you engage it
  • Clutch starts and stops immediately
  • Clutch is taking more time to engage
  • The engine fails to start when you engage the clutch
  • Visible fluid leakage from the PTO clutch


Repair and replacement are the only solutions to faulty PTO clutch systems. An expert should identify the defective part in the clutch system and recommend a solution.

Replacement becomes a viable solution if the clutch is too old or highly damaged for repair.

Lawn Mower PTO Clutch

Reason 3: Battery Issues

Just like vehicles, lawnmowers rely on a battery to start. If the battery is drained or is not working well, you may notice that the lawn mower engine dies when PTO is engaged. 

Most lawn mower battery issues are caused by loose terminal connections, corrosion, and over-draining.

How To Fix

Here are practical solutions to fixing a damaged battery making your lawn mower engine die shortly after sorting:

  • Test the battery with a multimeter and charge it to less than 12 volts
  • Inspect the battery for corrosion and clean and affected parts with baking soda
  • Inspect the battery wires and terminals for loose connections
  • Replace the battery if its old and has visible signs of wear and tear

Reason 4: Air Filter Issues

Dirt is a big enemy of your lawn mower’s engine because the mower requires clean air to run effectively.

If the mower air filters are damaged or clogged with debris, there won’t be enough free flow of air to facilitate the combustion of gas/fuel in the engine.

This issue may make the mower engine die shortly after engaging the PTO.

The most obvious signs that your lawn mower air filters are clogged include a surging lawn mower, the mower producing black smoke, and when the engine fails to start at all or makes strange sounds.

How To Fix

Inspect the air filters, then clean them if they are dirty. Alternatively, you can remove and replace them if there is extreme clogging or damage in the filters.

Reason 5: Poor Charging System

A poor charging system may not directly impact your lawn mower engines but reduces the battery’s effectiveness.

The battery won’t charge well when the charging system is faulty. Due to this, your engine will not start or stop immediately when you engage the PTO clutch.

Apparent signs that your lower battery system is ineffective include low fluid levels, visible signs of corrosion, and difficulty charging.


A battery is a sensitive unit of the mower and requires professional handling.

Unless you are skilled enough, you should seek professional assistance whenever you notice your lawnmower has a battery charging problem.

The expert should do the required tests, fix the issue, or recommend an entire battery systems replacement.

Reason 6: Ground Struck

Sometimes, your lawn mower engine may fail simply because the starter rope is stuck on the ground and hard to pull.

This scenario is common when the mower is placed in areas with tall grass or some debris is stuck on the lower part of your mower.


Adjust the current position of your mower to ensure no obstacles affect the functionality of the mower.

Alternatively, you can switch off the mower and disconnect the battery to look for grass, stones, or anything that might be blocking the start rope.

After the inspection, connect your mower again to see if it works.

Final Remarks

You might not prevent some issues affecting your lawn mower, but you can quickly fix them.

The above are possible reasons why your lawn mower engine dies when PTO is engaged. If a problem persists, seek a professional for better repair and fixing.

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