Don't let a stubborn lawn mower ruin your day!

Discover the reasons why your lawn mower won't start and learn how to troubleshoot the issue(s).

Lawn Mower Won't Start

Troubleshooting Starting Issues

Before you can fix a Toro mower starting issue, and there are many, you will need to troubleshoot and inspect each component individualy.

Starting issues with most Toro lawn mowers can be diagnosed in 3-7 minutes, with the required time increasing as the repairs become more complex.

The following troubleshooting steps are listed in order, from easiest to most complex to address.

Check the Fuel Level

If your Toro lawn mower won't start, start by checking the fuel tank to ensure it's not empty.

Running out of fuel is a surprisingly common issue to overlook. If it's empty, refill it with fresh gasoline.

Avoid using old or stale fuel, as it can cause starting problems.

Check the Choke

The choke is essential for cold starts. If your Toro mower struggles to start in cold conditions, it might be due to the choke not being set correctly.

When starting a cold engine, make sure the choke is in the "on" or "choke" position.

This restricts the air intake and enriches the air-fuel mixture, making it easier for the engine to start.

Adjust the choke accordingly, and you should see an improvement in starting performance.

Tighten the Spark Plug Wire

Mower Engine Spark PLug Wire is Connected

A loose or disconnected plug wire disrupts ignition. In the event of a non-starting mower, check the spark plug wire.

Ensure it is securely attached to the spark plug. A loose or disconnected plug wire can prevent ignition, causing starting problems.

Reconnecting the wire properly should resolve this issue.

Check the Fuel Valve

Fuel valve positioning is critical for proper engine function. If your Toro lawn mower fails to start, check the fuel valve (if equipped).

It should be in the "on" position to allow fuel flow to the engine.

Sometimes, this valve gets inadvertently turned off during storage or maintenance. Simply switching it to the "on" position can resolve the issue.

If the engine still doesn't start after ensuring the fuel valve is open, proceed with other troubleshooting steps.

Inspect Fuel Quality

If the fuel in your mower smells old or bad, it may be causing starting issues.

Drain the fuel tank completely and refill it with fresh, clean gasoline.

Examine the Air Filter

Move on to the air filter. Locate the air filter housing, typically near the carburetor.

Remove the air filter and examine it.

If it's dirty or clogged, cleaning it or replacing it with a new one can often resolve starting problems caused by poor airflow.

Clean the Carburetor

A clogged carburetor can prevent your Toro mower from starting.

Locate the carburetor and air intake. Remove the carburetor and clean the carb thoroughly.

You can use carburetor cleaner or refer to your mower's manual for specific cleaning instructions.

Inspect the Safety Features

Check for any engaged safety features that might be preventing your mower from starting.

This could include the blade control or the operator presence control (OPC).

Ensure these safety features are disengaged, temporarily, before attempting to start the mower.

If it still won't start, re-engage all safety features.

Inspect the Spark Plug

Inspecting a Spark Plug

Next, inspect and change the spark plug (if needed). Look for signs of wear, damage, or fouling.

If the spark plug appears worn or fouled, it's a likely culprit for the starting issue.

Replace it with the correct type of spark plug as specified in your mower's manual.

Inspect the Ignition Coil

If none of these steps resolve the issue, it's possible that the ignition coil is damaged.

Diagnosing and replacing the ignition coil may require professional assistance or guidance from your mower's manual.

If you are comfortable with removing and/or testing ignition coils yourself this igntion coil resistance chart for small engines should help.

Check the Shear-key

The flywheel's shear-key plays a role in timing.

If the flywheel shear-key is damaged or sheared, it can lead to timing issues, resulting in starting problems.

To address this, you need to remove the flywheel and inspect the shear-key for damage.

If it's compromised, replace it with a new shear key, according to your mower's specifications.

This repair can be more complex and may require some mechanical skill.

Sticky Valves

Sticking valves can disrupt engine airflow. Sticking valves can hinder the flow of air in and out of the engine, affecting its ability to start and run smoothly.

To address sticking valves, you likely need to disassemble and clean or lubricate the valve components.

If you're unfamiliar with engine valve maintenance, it's advisable to seek assistance from a professional technician to avoid further damage.

Test the Compression

Low mower engine compression is a complex and serious issue.

If you suspect your Toro mower has low compression, it's indicative of internal engine problems that require professional diagnosis and repair.

Low compression can be caused by various factors, such as worn piston rings or cylinder damage.

To diagnose a low-compression issue in a mower engine turn the engine over by hand, you should feel some resistance each time the piston moves toward the valves.

Attempting to fix this issue without proper expertise can lead to further damage, so it's best to consult a professional technician for a thorough assessment and repair.

Lawn Mower That Won't Start

Advanced Troubleshooting

If you encounter a starting problem that persists despite following the article's guidance, here are a few "trick" procedures you can try:

Physical Obstructions

Inspect the underside of the mower deck and the blades for any obstructions like debris, grass clippings, or foreign objects.

Clearing these obstructions may improve the mower's ability to start.

Make sure to properly tilt the mower so as to avoid oil getting into the intake or exhaust ports.

Inspect the Starter Cord

Ensure that the starter cord is not frayed or damaged. It should pull and return freely with little resistance.

A damaged cord may not engage the engine properly. Replace the cord if necessary.

Flywheel Magnet test

Inspect the flywheel magnets to ensure they are clean and free from debris.

Dirty or damaged magnets can affect the ignition system.

The flywheel magnets are located on the flywheel itself and, with each engine rotation, pass directly in front of the ignition coil.

Use a small magnet to locate the magnets that are built into the flywheel, if needed.

Throttle Position Test

Check the throttle control lever or knob to ensure it is in the proper position for starting.

Sometimes, incorrect throttle settings, or problems with the throttle linkage and springs, can impede starting.

Check Electrical Connections

Examine and clean all electrical connections, including those on the ignition switch, spark plug, and safety features.

Corroded or loose connections can disrupt the starting process.

Check for a Flooded Engine

If you've attempted to start the mower multiple times without success, it may become flooded with fuel.

Wait for a while to allow excess fuel to evaporate before trying again.

Remember that these additional steps are more specific and may not apply to all starting issues.

If the problem persists after attempting these additional steps, it's advisable to consult a professional technician or refer to your mower's manual for further guidance.

Is the Engine Seized?

If nothing else seems to be wrong, as far as you can tell, there is a possibility the mower's engine is seized.

While it is possible to fix a seized lawn mower engine (guide), it requires a little patience, a little know-how, and a workbench with a good basic set of tools.

Our seized engine guide explains the process in more detail.

Tools Required

Lawn Mower Tool Shed

Here is a list of the essential tools you'll need to troubleshoot and address common starting issues with your Toro lawn mower:

  • Spark Plug Wrench: This tool helps you remove and replace the spark plug efficiently.
  • Socket Set: A socket set with various sizes of sockets and a ratchet is essential for loosening and tightening bolts and fasteners.
  • Screwdrivers: Both flat-head and Phillips-head screwdrivers will come in handy for removing covers and accessing components.
  • Pliers: Standard pliers and needle-nose pliers are useful for gripping, bending, and holding small parts.
  • Carburetor Cleaner: Carburetor cleaner assists in cleaning the carburetor effectively.
  • Safety Gear: Ensure you have safety gear like gloves and safety glasses for personal protection.
  • Air Filter: If your air filter is severely clogged or damaged, you may need a replacement.
  • Fuel Container: Use a fuel container for safe fuel handling and disposal.
  • Clean Cloth: Keep a clean cloth on hand for wiping and cleaning components.
  • Owner's Manual: Your Toro mower's owner's manual is a valuable tool for reference and guidance during troubleshooting and repairs.

Having these tools ready will enable you to perform the necessary tasks efficiently and help address starting issues with your Toro lawn mower effectively.

Repair Tips

Prioritize safety and follow recommended precautions during troubleshooting.

Begin with basic checks like fuel levels, spark plugs, and air filters for quick issue resolution.

Check and replace old or poor-quality fuel with fresh gasoline to improve engine performance.

Consider carburetor cleaning if starting problems persist, and consult the manual for guidance.

Ensure all safety features are disengaged before attempting to start the mower.

For complex issues, seek professional assistance from a Toro technician.

Keep essential tools like spark plug wrenches, socket sets, screwdrivers, and pliers on hand for efficient troubleshooting.

Safety Precautions

As you work on your Toro lawn mower, remember to prioritize safety. Ensure the engine is off and the spark plug wire is disconnected to prevent unintended starts.

Wear safety gear, work in a well-ventilated area, and use the right tools.

Consult your mower's manual for specific safety instructions. Handle fuel carefully, be cautious of moving parts, and keep your work area clean and organized.

If you're uncertain about a repair, seek local professional guidance at a mower repair shop near you.