Top 14 Reasons Why Your Zero-Turn Mower Won’t Start + Troubleshooting Tips

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Lawnmowers are a reliable tool for maintaining a well-kept lawn. But what do you do when your zero-turn mower refuses to start? After trying multiple times, you might contemplate taking it to a repair center. However, before you reach for your wallet, it’s worth exploring some troubleshooting steps.

In this guide, let me assist you in identifying potential reasons for your mower’s non-starting issue, walking you through the diagnostic process to help you save both time and money.

Issue #1: Not Enough/Bad Fuel

An empty fuel tank or low fuel can likely cause most of the riding mower brands like Toro lawn mower to have starting problem. Bad fuel can also contribute if the wrong type of gas is used. Zero-turn mowers use gasoline with an octane number of 87 and a maximum ethanol level of 10%. 

zero turn mower fuel tank

Drain the bad gas from your lawn mower and replace it with the correct gas at the required level. Also, use fresh fuel in your mower to avoid gumming and moisture buildup.

Issue #2: Defective Spark Plug

Damaged, old, or dirty spark plugs affect your mower and can cause error in your lawn mower. If the gap is set inappropriately or the wires are not secure, starting issues may occur. 

Inspect the spark plug to see if the starting issue is related by removing it. Clean it if there is carbon buildup, and if damaged, replace it with a new one.

Issue #3: Defective Gas Cap

It might look simple, but a defective gas cap can cause your mower to have problems specifically with starting. A gas cap allows the passage of air through the vent. If the vent is clogged, it will restrict the fuel from leaving the tank.

zero turn mower defective gas cap

Perform a running test to determine if the cap is the problem. If your heavily used mower runs without the cap and dies after installation, it’s the issue. Try to clean the clog or replace the cap entirely if damaged.

Issue #4: Dirty or Clogged Air Filter

Air filters enable the engine to have clean air. If dirty, it will deny the engine access to clean air and prevent the mower from starting. 

A simple fix is to check the air filter. Remove it from the housing and clean any excess dirt using a dry cloth, if any. Hold the filter against a light source. If light penetrates the paper, that means you can reuse it. 

Issue #5: Dirty or Clogged Fuel Filter

A fuel filter can become clogged with fuel deposits over time. In such cases, our team recommends replacing the filter rather than attempting to clean it.

Issue #6: Defective Fuel Pump

Fuel pumps direct fuel to the carburetor using pressure. It becomes defective if it starts leaking fuel. When this happens, the carburetor won’t receive the quantity of gas it needs to start the engine.

zero turn mower defective fuel pump

Replacing the fuel pump will do. Remember to shut off the valve to stop fuel flow when removing the pump.

Issue #7: Dirty or Clogged Fuel Connections

The fuel line or hose could be clogged with dirt. This blockage can prevent fuel flow. Once you find the obstruction, try to remove it. 

If it proves challenging to remove, spray carburetor cleaner into the hose to loosen its grip. Replace the fuel line if you can’t remove the clog.

Issue #8: Dirty or Clogged Carburetor

A dirty carburetor can poorly regulate the quantity of air and fuel needed for combustion. When this happens, your 42-inch zero-turn mower won’t start. And in some cases, the lawn mower starts but will quickly die

husqvarna carburetor

To start, it’s a good idea to give the carburetor a thorough check for any sticky deposits. If cleaning the carburetor doesn’t resolve the issue, the next step is to consider replacing it with a new one. 

Now, I must emphasize that working on this component can be a bit technical. It’s strongly recommended considering a visit to a professional repair shop for this task. They have the expertise and tools necessary to handle this type of maintenance effectively.

Issue #9: Defective Battery or Loose Connections

A simple way to check if you have a broken battery is to charge it. If it can’t hold a charge for an extended period, the battery is defective and needs replacement. 

Issue #10: Bad Safety Switch

All zero-turn mowers have a safety switch to keep you safe. If it gets detective, your mower may fail to start. You need to replace it immediately.

Issue #11: Defective Ignition Switch or Coil

The ignition switch is where you insert your key to start the mower. It could be a problem if the key isn’t properly inserted. 

testing mower's ignition coil

Issue #12: Bad Starter Solenoid

A solenoid incites the motor to run the engine [1]. This component is defective if the wires get hot and emit smoke. Another indication is if you turn the ignition key and it makes a click sound. Once you identify this to be the fault, replace it.

Issue #13: Wrong Starting or Operating Procedure

Following the wrong operating procedures can cause your Zero-Turn starting issues. Refer to your user manual to ensure you follow the correct steps.

Issue #14: Bad Charging System

Not only will a faulty charging system charge the battery poorly, but it will cause the battery to drain faster. Once you pinpoint the issue lies in the charging system, take it to a repairer. 

You may not have the experience to deal with the components that make up the system. 


What is the first thing to check if the lawnmower won't start?

The first thing to check if the lawnmower won’t start is the fuel level. Top up if it’s low, then check the other parts such as fuel and air filters, carburetor, etc. 

Why will my lawnmower turn over but not start?

Your lawnmower may turn over but not start due to issues like dirty or poorly connected spark plugs and a clogged carburetor. 

Read Next: Why Lawn Mowers Backfire


Eventually, you may encounter starting problems with your zero-turn mower, but understanding the root causes is crucial to prevent more serious breakdowns.

So, I have outlined the typical culprits behind starting issues in zero-turn mowers, along with effective solutions. This knowledge will help you stay composed and informed when your mower refuses to start.

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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