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10 Reasons Your Zero Turn Mower Won’t Turn Over

It’s frustrating when you finally find time in your busy schedule to get your lawn mowed only to find out your zero turn won’t turn over. I offer some tips to check when you run into this problem so you can your mower up and running again.

A zero turn mower won’t turn over when there is a lack of fuel, air restriction, bad starter, bad battery, bad spark plug or loose wires on your mower. Lack of fuel to the engine can be the result of a low fuel level, plugged fuel filter, clogged fuel lines, faulty fuel pump or dirty carburetor.

Zero turn mower won't turn over

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, knowledge or are not in the condition to perform the repair safely.

This is Why Your Zero Turn Mower Won’t Turn Over

Bad Spark Plug or Loose Spark Plug Wires on Your Zero Turn Mower

A fouled spark plug that is covered in carbon or oil causes a zero turn to misfire. It can’t produce the spark needed to ignite the fuel and air mixture to form a combustion in the cylinder.

A plug that is not gapped correctly or has loose spark plug wires can also result in your zero turn not turning over.

Remove the spark plug using a socket. Most model engines use either a 3/4” or 5/8” socket, but this can vary on your zero turn.

Inspect the tip of the spark plug for excessive dirt. This can be cleaned, but it should be replaced when the tip is very dark. Replace a spark plug that has a broken porcelain or burnt electrode.

Reinstall the cleaned spark plug or replacement plug. Gap the plug to the engine manufacturer’s specification and confirm the wires are securely attached.

It is good practice to replace your spark plugs annually during your routine zero turn maintenance to minimize spark plug problems during the mowing season.

Dead or Bad Battery on Your Zero Turn Mower

A zero turn with a dead battery will not turn over. Charge your battery and check it to see if it is able to hold a charge. If it fails to hold a charge, you must replace your battery with a new one.

A new lawn mower battery can be purchased at your lawn mower servicing dealership or at your local hardware or automotive store. Make sure you bring your old battery with you when you purchase a new one.

Most of them time, you will be charged a core charge if you don’t provide them with your old battery.

Charging a zero turn lawn mower battery:

Use a battery charger to charge your 12-volt battery. Before you continue, wear protective gear to protect your eyes and skin from electrical shock. Follow these steps to charge your lawn mower battery with a charger:

  • Access the battery and terminals. You may need to use a screwdriver to uncover the battery. Do not remove the battery from the casing.
  • Connect the charging cables beginning with the positive cable first. This is the red cable or the one with the plus sign. Place the cable on the positive battery terminal.
  • Attach the negative cable to the negative battery terminal. This is the black cable or the one with the minus sign.
  • Do not touch anything that doesn’t have a rubber coating to prevent electrocution.
  • Set the charger’s voltage and amperage level to the desired level. The average volt level for lawn mower batteries is usually 12 volts. More amperage charges the battery faster. Start with two amps and work up to no more than 10 amps. A slow charge is best.

Loose Wires and Connections on Your Zero Turn Mower

Check the electrical wires and connections on your zero turn. When you operate your zero turn, there is a constant vibration that can cause your connections to become loose. Water can also collect in your connections and make them corrode and not function proper.

Clean any corrosion you find on the connections using a wire brush and a baking soda solution. You can make this solution using 2 cups of water to 3 heaping tablespoons of baking soda. If your connections and terminals are severely corroded, replace them.

Bad Starter Solenoid on Your Zero Turn Mower

A starter solenoid is an electromagnetic switch that, when engaged, initiates the starter motor to turn over your zero turn’s engine.

The starter solenoid can go bad when the spring becomes weak or the copper plate begins to corrode causing your zero turn to no longer turn over. A weak starter, bad battery or bad ground can also cause the solenoid to fail.

Before you test your starter solenoid, you must have a fully charged battery. Continue testing the solenoid by using the steps to diagnose a bad starter solenoid in “How to Tell Your Lawn Mower Solenoid is Bad”.

Plugged Air Filter on Your Zero Turn Mower

When mowing, a lot of dirt and debris is stirred up. This dirt can collect on your air filter causing insufficient air flow to the engine. Your zero turn will not turn over when there is an air restriction.

Replace your filter with a new filter once a year. Check and clean your air filter several times during the mowing season and more often when mowing in dusty conditions.

How to clean a zero turn paper air filter element

  • Remove the air filter from the air filter housing.
  • Wipe out any dirt remaining in the housing with a clean dry cloth. Make sure you don’t allow any dirt to fall into the air intake.
  • Tap the solid part of your air filter against a solid surface to release as much dirt as you can make fall from your filter. *Do not use compressed air to blow out your air filter. This can damage it.
  • Determine whether you can reuse your air filter by holding it up to a light source. Check for light shining through the paper. If you can see light, go ahead and reuse the filter. If you can’t, replace it with a new filter.
  • Install the air filter and replace the air filter cover.

Lack of Fuel or Bad Fuel in Your Zero Turn Mower

Your zero turn will not start or turn over when the mower doesn’t have fuel. Check your fuel tank for fuel. You have a fuel leak causing you to go through more fuel than usual. If you find you are low on fuel, refill with fresh fuel. Read this article for more information on finding where your mower is leaking fuel.

Running old or bad fuel through your fuel system can cause clogging or degradation of the fuel components. Your mower will not turn over if it is unable to get fuel to the combustion chamber.

Much of today’s gasoline contains ethanol. While ethanol is an environmentally friendly product and okay to run in most vehicles, it can damage your small engine. Because of this, make sure you are using unleaded gasoline with an ethanol content no greater than 10 percent.

Ethanol is corrosive to the fuel system. It attracts moisture from the air. Overtime, this air and fuel mixture will separate from the gasoline and sink to the bottom of your fuel tank. This solution runs hot and can damage your engine.

Old fuel can break down as soon as 30 days after purchase. It will leave behind a gummy substance that clogs the fuel system components preventing a good flow of fuel.

If your fuel has been sitting for a long period, remove the fuel from your fuel tank using a siphon. Fill with the right kind of gasoline for your gas-powered zero turn. Add a fuel additive like Sea Foam Motor Treatment to stabilize your fuel, reduce moisture and clean your fuel system.

Learn mower about the advantages of using Sea Foam Motor treatment in your zero turn and why I choose to add it to every tank of gas in my zero turn.

Plugged Fuel Filter or on Your Zero Turn Mower

Your zero turn uses a fuel filter to strain the fuel as it leaves the fuel tank and before it flows into your fuel system and engine. It is designed to remove dirt and contaminants to prevent engine damage.

The fuel filter should be replaced annually. I change mine when I perform my annual service so I don’t have to worry about it clogging during the mowing season.

Replace the filter by removing the clamps and fuel filter from the fuel lines. Install the new filter with the arrow on the side of the plastic housing facing in the direction of your fuel flow. This means the arrow needs to be pointed toward your carburetor and away from your fuel tank.

Clogged Fuel Lines on Your Zero Turn Mower

Another fuel component that can become clogged causing your mower to not turn over because of a lack of fuel is the fuel line.

Check for a restriction in each section of fuel line by shutting of your fuel flow. Remove the furthest end of a section of fuel line from the mower and placing it in a container placed lower than the fuel tank.

Turn on your fuel flow. If you get good flow out of your line and into the container, your fuel line is okay. Go ahead and reinstall it onto your mower. If you are not getting good flow, remove the section of fuel line from the mower.

Spray carburetor cleaner into the line to loosen the clog. Next, blow compressed air through the line to remove the blockage. If you are unable to remove the clog, buy a new fuel line and install it on your zero turn.

Bad Fuel Pump on Your Zero Turn Mower

When the fuel pump is not able to build pressure and pump fuel to the carburetor, your mower will fail to turn over because it is not getting fuel.

To identify a bad fuel pump, first check to make sure you are getting fuel to the inlet port of the fuel pump. You may have already verified this when checking for a clog in your fuel lines.

Once you have confirmed you are getting fuel to the fuel pump, shut off your fuel supply and disconnect the fuel hose from the carburetor. Place the hose in a container. Turn on the fuel supply and start your zero turn. Watch for a steady or pulsating flow of fuel flowing from the fuel line into the container.

If you are getting good flow, your fuel pump is working fine. If not, you should replace your fuel pump with a new pump.

Dirty Carburetor on Your Zero Turn Mower

The carburetor can gum up and become dirty from running old fuel. The carburetor components can become clogged or stuck. When this happens, the correct amount of fuel is not released into the combustion chamber to form a combustion. Your zero turn will not turn over.

If you are not getting fuel to the engine and have verified you are getting fuel to the carburetor, perform this check before you begin disassembling your carburetor: Remove the air filter and spray carburetor cleaner into the air intake. Start your mower. If it starts, runs and then shuts down, you need to clean your carburetor.

You will have to work with a lot of little parts when cleaning your carburetor. If you want to attempt this yourself, follow my instructions for cleaning a zero turn carburetor here. Otherwise, have your local repair shop clean it for you.

Still Having Problem with Your Zero Turn Mower?

If you have checked the above items and none of them resolved the problem with your zero turn mower turning over, you may want to check out the articles below or take your mower to your local lawn mower repair shop for further diagnosis.

You can also check out my guide for more problems and solutions: Common Zero Turn Problems: How to Fix Them