If you’re anything like me, I enjoy mowing at the beginning of the season, but it becomes a big chore for me by the end of the season. It’s increasingly frustrating when your zero turn mower dies in the middle of your lawn. Because there are so many items that can affect your mower shutting down, it can be difficult to know just where to start and what to check.
A zero turn lawn mower starts then dies when it isn’t receiving air, fuel or spark it requires to run. This can be due to a plugged air filter, bad fuel, clogged fuel components, dirty spark plugs and bad ignition coil. An incorrect engine oil level, plugged cooling fins and plugged mower deck can cause your engine to overheat and shut down.
Keep reading for a full list of items that can cause your zero turn to start and then quit.
Reasons Your Zero Turn Starts Then Dies
Bad or Old Fuel in Your Zero Turn Mower
Fuel that has been sitting in your mower for a while can begin to break down and become less effective. Most gasolines sold today contain ethanol, a corn-based product. This product attracts moisture from the air that is corrosive to the fuel system. When this solution evaporates, it can leave gummy deposits behind. This can clog your fuel components.
Clogged fuel components prevent your zero turn from getting the fuel it needs to continue to run. Not only will this solution clog the fuel system, over time it separates from the gasoline and sinks to the bottom of the fuel tank. This solution will run hot when run through your engine causing potential engine damage.
Make sure you are running fresh unleaded gasoline through your gas-powered zero turn lawn mower. Because of the damage ethanol has on your mower, do not use any fuel with an ethanol content greater than 10%. Read more about the right gas to use in your zero turn here.
If your mower has old fuel in the tank, drain the fuel tank using a fuel siphon into an approved container. Set this container aside for recycling. Fill your fuel tank up with the right gasoline. Add a fuel additive to it to stabilize your fuel system.
I use Sea Foam Motor Treatment in each tank of fuel. It stabilizes the fuel, reduces moisture and cleans the fuel system. It’s a safe petroleum-based product for your zero turn. Read more about the positive effects of Sea Foam here.
Plugged Fuel Filter on Your Zero Turn Mower
When the fuel filter becomes plugged with dirt and no longer allows fuel to pass through, your engine will die from the lack of fuel. Replace a plugged fuel filter with a new one. When installing the filter, make sure the arrow shown on the side of the filter housing is pointed in the direction of the fuel flow.
Clogged Fuel Lines on Your Zero Turn Mower
A gummy substance from running old fuel can run through the fuel system and create a blockage in the fuel line. This can cause your zero turn to die after it has been running a while because the engine is no longer getting fuel.
Check for blockages in your fuel lines using the fuel shut-off valve to start and stop fuel flow while checking each section of fuel line for fuel flow. If you find a fuel line that has a blockage, turn off the fuel supply and remove the fuel line from the mower.
Spray carburetor cleaner into the fuel line. This is to loosen up the clog. Follow this with blowing compressed air through the line to remove the blockage. If you are unable to dislodge the blockage to open the fuel line, install a new fuel line on your mower and turn on your fuel supply.
Faulty Fuel Pump on Your Zero Turn Mower
Most fuel pumps used on zero turn mowers are vacuum pumps. They build pressure off the engine block and pump fuel to the carburetor. Pumps can fail after time from wear or it can begin to degrade from fuel.
To determine you have a bad fuel pump, confirm you are getting fuel flow to the fuel pump by checking flow through the fuel line. You may have done this in the prior step. Next, check fuel flow out from the fuel pump. Turn off your fuel flow and remove the fuel line from the carburetor. With the line placed in a container, turn on your fuel flow and start your zero turn.
Watch for a steady or pulsating flow of fuel out of the line indicating your pump is working. If you don’t get good flow, replace the fuel pump.
Dirty Carburetor on Your Zero Turn Mower
The carburetor regulates the amount of gas and air allowed into the combustion chamber to form a combustion. The components on your carburetor can become clogged and fail to release the amount of fuel your engine needs to run causing it to run sluggish or die.
Before you disassemble and clean your carburetor perform these simple checks to determine the problem is in your carburetor:
- Confirm you have fuel flow to the carburetor. You should have verified this if you check fuel flow out of your fuel pump.
- Remove your air filter from the air filter housing.
- Spray carburetor cleaner into the air intake and start your mower.
- If the zero turn starts, runs fine and then shuts down, your problem may be in the carburetor.
Remove the carburetor from your zero turn. Disassemble it and clean the carburetor. Refer to this article for carburetor cleaning steps. Bring your mower to a small engine repair shop if you choose to have someone else tackle this job for you.
Plugged Air Filter on Your Zero Turn Mower
One of the requirements for your engine to run is air. If your zero turn died while mowing, it can be the result of a plugged air filter. When it becomes plugged, air can no longer pass through the filter and to the engine.
You should replace your air filter once a year and check it several times during mowing season to keep it clean. You’ll need to clean it more frequently when you are operating the mower in dusty conditions. Follow these instructions to clean your paper air filter:
Clean a zero turn air filter
- Remove your paper air filter element from the housing.
- Wipe out any dirt remaining in the housing with a clean dry cloth. Don’t allow dirt to fall into the air intake.
- Tap it against a hard surface to remove as much dirt as you can get to fall out of the filter. Don’t use compressed air as this will damage the paper.
- Hold your filter up to a light source. Replace your filter with a new one if light is not shining through the paper element. If it is, go ahead and reuse it.
- Install your air filter and reattach the filter housing cover.
Plugged Engine Cooling Fins on Your Zero Turn Mower
The engine can overheat after it has been running awhile causing your mower to die. One of the items that can cause overheating is plugged engine cooling fins. The fins need to be kept clean and free of debris so it can efficiently push air around the engine block and cylinder head to keep it cool.
Remove any dirt you find on your cooling fins and replace any broken fins. Remove dirt from around your engine block and around your engine shroud. Make sure your heat shield is correctly installed to help with the air circulation.
Low Engine Oil Level in Your Zero Turn Mower
It’s important to check the engine oil level in your zero turn before each use. Many mower owners skip this step. Checking the engine oil level using the oil dipstick is a fairly quick process. Catching a low engine level before it causes engine damage can save you from a costly repair expense.
Running your zero turn with a low engine level can cause your mower to overheat and shut down. When there isn’t enough engine oil to lubricate the internal engine components, friction among the parts will build creating heat in the crankcase. This excessive heat can begin burning oil and parts in your engine.
When you run into a problem with your mower shutting down due to a low engine oil level, you can attempt to add more oil to correct the level and start your mower. Most of the time, if your mower shut down because of a lack of lubrication, the simple fix of adding more engine oil isn’t going to work.
Most likely, significant engine damage was caused. It is best to have an experienced small engine mechanic take a look at your mower to find out how much damage occurred.
Too Much Engine Oil in Your Zero Turn Mower
Not only can low engine oil cause your engine to die, but also too much engine oil can make your zero turn shut down. Excess oil will cause pressure to build in the crankcase. Read more about the effects of running too much oil here.
If you find, after checking your engine oil, that your level is too high, remove a little bit of oil. Oil can be removed out of the drain plug, oil filter or out of the oil fill area using an oil evacuator or turkey baster. Continue to remove and add engine oil until the level is corrected.
Dirty Spark Plug or Loose Connections on Your Zero Turn Mower
A dirty spark plug can foul out causing your zero turn to die. Check your mower for a spark plug that is dirty or isn’t correctly gapped. Loose spark plug wires can also be the cause your mower runs sluggish or dies.
Remove your spark plug and clean the spark plug if it is dirty. If it happens to be very dark in color or damaged, install a new spark plug. Make sure it is correctly gapped according to your engine manufacturer specification and the spark plug wires are securely attached.
Bad Ignition Coil on Your Zero Turn Mower
The winding on the ignition coil can separate and short out when your mower is hot. When this happens, the spark plugs are unable to get the voltage they need to create spark. This can cause your mower to die after it’s been running a while.
Identify a bad ignition coil using an ohm meter to check for a break in continuity. Replace the ignition coil if you find there is a break.
Choke is in the Wrong Position on Your Zero Turn Mower
Your zero turn has a choke to allow more fuel to be allowed into the combustion chamber by restricting air flow. This is needed to start your engine when it is cold. If you leave your choke on after your engine heats up, your zero turn will die. Make sure your choke lever is in the right position.
Bad Battery or Charging System on Your Zero Turn Mower
If your mower won’t hold a charge or the charging system is bad, it can die after running for a while. Make sure you are running your engine at high speed. Don’t allow your mower to idle for long periods of time because engine power is required to charge the battery.
There are some steps you can take to check the condition of your battery and charging system which I explain this this article. If after performing these tests, you find you have a bad battery, replace your battery. When you find the charging system isn’t working right, I highly recommend having an experienced mechanic diagnose and repair the problem.
Bad Zero Turn Mower Gas Cap
The gas cap has a small hole in it designed to allow air to pass through the cap. When this vent is plugged, the fuel tank will form a vacuum not allowing gas to flow out of the tank. Your mower will start and run with a bad gas cap, but it will shut down once it has run for a while creating a vacuum in the tank.
Plugged Zero Turn Mower Deck
A plugged mower deck can make your engine work hard, overheat and shut down. When grass collects under your mower deck, extra strain is put on the engine when it must turn the blades through a deck full of debris. Dull mower blades can further magnify the problem.
Regularly scrape your mower deck and sharpen your mower blades. Not only will a clean deck not put extra strain on your engine, it will provide you with a nicer cut. The deck uses the blades and area under the deck to create air movement to lift and cut your grass.
Zero Turn Problems & Solutions
Still having problems with your zero turn? Check out the guide below for common problems and solutions for your zero turn mower. This is a handy guide to bookmark and keep on hand to help you identify problems with your zero turn throughout the mowing season.
Common Zero Turn Problems: How to Fix Them