Your mower died while you were in the middle of mowing your lawn. Now you may be stuck with a lawn mower that won’t run. It’s easy enough to push it back to your garage, but if you have a riding mower or zero-turn, it will take a little more effort.
Your Toro lawn mower starts then dies when the engine doesn’t receive sufficient air or fuel flow.
This can be from bad fuel, a plugged filter, a dirty carburetor, or a bad gas cap. An insufficient engine oil level, clogged deck, and dull mower blades can also cause your mower to die while mowing.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Why Your Toro Lawn Mower Starts Then Dies While Running
Gas Tank is Empty
The most obvious reason why your lawn mower died is that it ran out of gas. I had to mention it because someone out there may have missed checking the gas.
It’s been the problem when I worked with customers to troubleshoot their starting problems so I thought it is worth mentioning.
Repair: Fill your gas tank with fresh gas
Bad or Old Fuel
Fuel can go bad relatively quickly since gas only has about 30 days before it begins to degrade and become less effective.
If you are using fuel with a little ethanol content, the ethanol can attract moisture. When this moisture evaporates, it can cause gumming which can clog your fuel system.
Most vehicles run fine with ethanol, but ethanol can be detrimental to your small engine. Ethanol is corrosive to your fuel system. When gas sits long enough, water and gas can separate and sink to the bottom of your gas tank.
Here are tips to ensure you get the best fuel results:
- Use your fuel within 30 days
- Only buy your gas from a busy gas station
- Don’t leave your fuel outdoors where it can attract moisture
- Store your fuel in a dry place
- If you are unable to use your fuel within 30 days, add a fuel additive to stabilize your fuel. I use a product called Sea Foam Motor Treatment. It’s a petroleum-based product that won’t harm your engine. It stabilizes your fuel, removes moisture, and cleans your fuel system. To read more about using Sea Foam in your lawn mower, visit “Why Use Sea Foam Fuel Additive in a Lawn Mower”.
Repair: Remove your old gas by draining your fuel tank and refilling it with fresh gas that includes a fuel additive to clean your fuel system and stabilize your fuel. Do not dump your old gas on the ground. You need to properly recycle it.
It’s easy to go to the fuel pump and accidentally put the wrong fuel in your gas container. Each pump is a little different. They could have multiple dispensers for each type of fuel or one dispenser where you need to push a button to select the type you want.
If that’s not difficult enough, you may see some extra yellow, blue, or green handles mixed in among the pumps that signify E85, Ethanol-Free, and Diesel fuels respectively. Read the label on your pump to make sure you are getting the right fuel for your Toro lawn mower.
Buy a gas that has an octane rating of 87 or higher along with an ethanol content no greater than 10 percent. This fuel is often sold as E10 or Regular fuel at your local gas station.
The lower the ethanol content, the better. Do not use fuels with ethanol contents higher than 10 percent as it can cause great damage to the small engine in your mower.
For a more in-depth look at the best types of fuel to use, check out my This is the Kind of Gas to Use in Your Toro Mower.
Repair: Drain the fuel tank, flush the fuel tank, and fill it with fresh fuel treated with Sea Foam Motor Treatment.
Your lawn mower’s carburetor may cause your mower to die while running. The carburetor controls the amount of fuel and air that is mixed so the engine can form combustion in the cylinder.
When the carburetor becomes dirty and gummed up, it may no longer function and allow fuel to flow out of the carburetor.
Repair: Most of the time the carburetor can be cleaned, but other times the buildup of deposits can be so bad that it is unable to be efficiently cleaned.
You may not even want to tackle cleaning your carburetor and find it easier to just purchase a new one and replace it.
If you are mechanically inclined you can try to clean your carburetor yourself, otherwise, a lawn mower repair shop will be able to help you. Read my steps on how to clean your lawn mower carburetor here.
Faulty Fuel Pump
Your mower may use a fuel pump if it needs to pump fuel up to the carburetor because it sits higher than the fuel tank. Pressure is built inside the pump and pushes fuel to the carburetor.
A pump can fail over time causing it to no longer have the ability to build pressure.
You may be able to see your pump is damaged or leaking at the seams, other times you will have to test whether the pump is working. You can do this by using your fuel shut-off valve or hose clamps to stop and start fuel flow.
Check to make sure you are getting fuel to the inlet port of the fuel pump. Once this is verified, check the opposite side (outlet port) of the pump for pumped fuel.
Repair: Replace your fuel pump if you are not seeing a steady or pulsating flow of gas from the outlet port on the fuel pump.
Plugged Fuel Filter
Dirt and other deposits left behind by bad fuel can collect in your filter and prevent gas from passing through the filter. When you can’t get gas to your engine, your mower will die.
Repair: Replace your fuel filter if gas is being restricted by the filter. You can use clamps to stop and start flow to see if the blockage is with your fuel filter or if it may be in your fuel lines.
Toro fuel filters are relatively inexpensive. I always change mine out once a year.
Clogged Fuel Lines
While you were checking for a failed fuel pump or bad fuel filter, you may have found your fuel restriction problem is in one of your fuel lines.
Repair: To clear the line, remove the fuel line and spray some carburetor cleaner in the hose to help loosen the clog. Next, blow air through the line using a can of compressed air until the clog is removed.
Reinstall the line. If you can’t get the clog removed or you find your fuel lines are dry and cracked, you can easily replace it with a new fuel line purchased online or at your local hardware store.
Bad Gas Cap
You may not have noticed your gas cap is built to allow it to vent. When air is unable to pass through the cap, a vacuum can form in your gas tank that prevents fuel from flowing out of the tank. This will surely cause your mower to die while mowing.
Remove your fuel cap and start your lawn mower, and allow it to run. If your mower no longer dies, this can be your problem. Be careful to not let any dirt or debris enter your fuel system when testing your mower without the fuel cap.
To confirm the problem, place your cap on your mower and let it run a little longer to see if it dies.
Repair: If you are unable to unclog the vent by cleaning, you need to replace your gas cap.
Clogged Air Filter
When you’re running your Toro mower, you kick up a lot of grass clippings and dirt. This debris can collect in your air filter and plug it so the engine is no longer able to get air.
When the engine is starved of air, your mower will shut down and possibly overheat causing internal engine damage.
You must check your air filters regularly to keep them clean. I like changing my air filters annually and cleaning them about once a month. Your air filter may become plugged sooner than the average homeowner if you are operating in pretty dusty conditions.
Repair: Remove the air filter. If your air filter is a paper filter, knock the dirt out of the filter by tapping the filter against a solid surface.
Hold the air filter up to a light and make sure you see light through the filter. You will need to replace the air filter if you are unable to see light through the paper filter.
Your lawn mower may use a different style of air filter. For cleaning procedures for other types of filters, read this article.
Dirty or Damaged Cooling Fins
Cooling fins can get packed with dirt, grass, and oil. When the fins are broken or packed with debris, the fins are not able to effectively circulate air around the engine block and cylinder head to keep your engine cool.
Repair: Remove the engine cover and clean the cooling fins. Replace any damaged fins.
Too Much Oil or Too Little Oil
Too much oil in your lawn mower can cause your engine to smoke and die while mowing. The smoke can clog your air filter causing your engine to look elsewhere for air.
Too much oil in your lawn mower can cause significant damage including internal engine damage and the possibility of having to replace your engine.
Too little oil in your mower will cause additional friction in the engine that can cause your engine to overheat and die.
Repair: Perform your engine oil change according to Toro’s recommendations. Always fill oil to the correct oil fill levels.
Clogged Mower Deck & Dull Blades
A mower deck that is packed with grass and dirt or a deck that is running dull blades can cause your engine to have to work harder. Your blades may be hitting debris each time it turns putting a draw on your engine. This can make it overheat and shut down.
A plugged mower deck and dull blades won’t only affect how well your mower runs, but it also affects how well it cuts.
When your deck and blades are in this condition, you can get bad-cutting results where your lawn is being cut unevenly. Check out this article on Toro’s uneven cut.
Repair: Inspect your mower deck for any damage. Scrape the deck to remove debris and sharpen the blades. Always run your mower at full throttle when cutting grass. Avoid cutting wet grass or very tall grass.
Still Having Problems with Your Toro Lawn Mower?
It would be great to own a problem-free lawn mower, but it’s never the case. No matter what brand mower you own, you’re going to run into problems the longer you own it.
To help you troubleshoot your mower problems, I have put together a list of common problems along with causes and solutions to fix them. Check out Common Toro Lawn Mower Problems and Solutions to learn more.