Why won’t Toro lawnmower start?

Quick Answers

There are several common reasons why a Toro lawnmower may not start:

• The spark plug is fouled or faulty
• The air filter is clogged
• The fuel is old or contaminated
• The carburetor is dirty and needs cleaning
• The blade safety switch is faulty
• The battery is dead (for electric start models)

The most likely culprits are issues with the spark plug, air filter, fuel system or battery. Checking and replacing these components is usually the quickest way to get a Toro mower started again.

Steps to Diagnose the Problem

Here are the key steps to take to diagnose why your Toro mower won’t start:

Check the Spark Plug

The spark plug is essential for igniting the fuel-air mixture in the engine. A fouled or faulty plug is a very common reason for failure to start.

To check the plug:

1. Remove the spark plug wire and use a spark plug socket to unscrew the plug
2. Inspect the plug – it should be light brown in color. A wet or black plug means it’s fouled and needs replacing.
3. Check the spark plug gap – it should be around 0.030 inches.
4. Reinstall the plug and connect the wire. If there’s still no spark, the plug may need replacing.

Replacing a worn or fouled spark plug can often get a stubborn Toro mower started right up.

Inspect the Air Filter

A clogged air filter chokes the engine and prevents proper starting.

To inspect the filter:

1. Locate the air filter housing on the side of the engine
2. Unlatch and open the housing to access the filter
3. Remove the foam or paper filter element
4. Check for dirt, debris, oil or damage – clean or replace as needed
5. Reinstall the filter and close the housing

Having a clean, unobstructed air filter is vital for engine operation and starting.

Check the Fuel System

Fuel problems like contamination, old gas buildup and carburetor issues can all prevent successful starting.

Checks to make on the fuel system:

• Drain old gas and replace with fresh fuel – expired gas can clog the carburetor
• Inspect fuel lines and filter for cracks or debris
• Check that fuel flows freely when the tank is full
• Remove and clean the carburetor jets and bowl if buildup is suspected
• Make sure the fuel shutoff valve is open

Cleaning contaminated or stale fuel from the carburetor and lines is often the solution for hard starting issues.

Check the Blade Safety Switch

Toro mowers have a blade safety switch connected to the seat or handlebars that disables the starter when disengaged as a precaution.

If this switch is faulty or misadjusted, it can prevent the mower from starting.

To check the switch:

1. Sit in the operator seat or depress the handlebar levers
2. Try turning the ignition – if the mower now starts, the switch needs adjustment or replacement

Charge or Replace the Battery

For Toro mowers with electric start, a dead or weakened lead-acid battery can cause start failure.

Troubleshoot the battery:

• Check the charge level – charge fully if low
• Load test to determine if the battery needs replacement
• Check battery cable connections are clean and tight
• Replace battery if charging does not restore function

A fully charged, working battery is critical for electric start to function on Toro mowers.

Causes and Solutions Table

Problem	Cause	Solution
No spark	Faulty spark plug	Replace spark plug
	Loose plug wire	Reconnect wire
	Faulty magneto	Repair/replace magneto
Engine flooded	Choke left on	Open choke fully
	Overpriming	Dry spark plug, crank engine
Fuel delivery issues	Blocked fuel filter	Replace fuel filter
	Faulty fuel pump	Test/replace fuel pump
	Clogged carburetor	Clean/rebuild carburetor
Compression issues	Worn piston rings	Install new piston rings
	Leaking head gasket	Replace head gasket
	Valve issues	Adjust/repair valves
Safety interlock engaged	Faulty seat switch	Bypass/replace switch
	Faulty blade brake switch	Bypass/replace switch

This table summarizes some of the most common Toro starting problems, causes and solutions to check.

Conclusion

Diagnosing issues with Toro mowers that won’t start requires methodically checking the engine’s vital systems. Focus your troubleshooting on the most likely culprits like the spark plug, air filter, fuel delivery and safety switches first. Replacing worn parts and giving the engine a thorough cleaning to remove grease buildup will often get the mower running again. For complex issues, take the mower to an authorized Toro service center for professional repairs. With routine maintenance and proper winter storage, you can help prevent starting problems altogether and extend the life of your Toro mower.