14 Reasons Your Spartan Lawn Mower Won’t Start

A zero-turn mower is a great piece of equipment to maintain your sizable lawn. It provides a great cut and considerably reduces the amount of time it takes to complete the task when compared to other types of mowers. You rely on your Spartan zero-turn. That’s why it’s frustrating when it doesn’t start.

A Spartan lawn mower won’t start when it doesn’t get the air, spark, and fuel required to create an explosion in the cylinder.

This can be caused by a clogged fuel line, plugged fuel filter, dirty carburetor, plugged air filter, bad spark plug, faulty switch, bad battery, and more.

Performing regular maintenance on your Spartan mower will help minimize problems with your Spartan lawn mower. You may also catch small problems before they develop into larger costly ones.

Keep reading for additional items that will keep your Spartan mower from starting.

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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.

Reasons Your Spartan Lawn Mower Won’t Start

Empty Fuel Tank

I only mention an empty fuel tank because some people forget to check this obvious reason for a Spartan lawn mower not starting. You may have developed a fuel leak and not realized you were going through more fuel than usual.

You may have simply forgotten the last time you bought fuel or the fuel gauge isn’t working right so you didn’t realize you ran out of fuel.

Solution: Check the fuel tank to make sure you have a sufficient amount of fuel to start and run your mower. Check for a fuel leak or faulty gauge and repair as necessary. Add fresh fuel to your lawn mower.

Old Fuel

Gas for a Spartan Lawn Mower

Old fuel can have a negative effect on your Spartan lawn mower whether it’s a diesel-powered Spartan or a gas-powered Spartan. Because most mowers in Spartan’s lineup are gas-powered zero turns, this guide focuses on gasoline and its effects.

Gas will begin to break down and become less effective as quickly as 30 days after purchase. This will result in problems that can keep a mower from starting. Gasoline contains an alternative plant-based fuel, often made of corn, called ethanol.

While adding ethanol makes gasoline more environmentally friendly than gas without ethanol, it is not good for the small engine used on your Spartan lawn mower.

Ethanol naturally attracts moisture out of the air that can cause premature corrosion in the mower.

This ethanol and moisture mixture will leave behind gummy deposits that will restrict the fuel supply when it clogs the fuel lines and causes small components in the carburetor not to function properly.

Spartan lawn mowers require an unleaded gas with a minimum octane rating of 87 and a maximum ethanol content of 10%. Do not use gas with ethanol levels higher than this like those sold as E15 and E85 gas.

These contain ethanol levels up to 15% and 85% respectively. Ethanol-free fuel is the best type of fuel to use in your Spartan mower, but it is a little pricey.

Use Fresh Fuel

Because of how quickly gas can start to go bad, purchase an amount of fuel that you can consume within 30 days. If you are unable to use it within 30 days, add a fuel additive like Sea Foam Motor Treatment to your fuel to stabilize it so it lasts a little longer without breaking down.

Solution: When you find old fuel in your Spartan mower, drain the fuel tank using a fuel siphon pump. Mix your fresh gas with Sea Foam or STA-BIL to stabilize the gas and reduce moisture in the fuel system.

Read more about why I choose to use Sea Foam in every tank of gas in “Use Sea Foam Additive in a Lawn Mower to Stabilizer Your Fuel“.

Bad Gas Cap Causes a Spartan Mower Not to Start

A Spartan mower gas cap is designed with a vent to allow air to pass through the cap. This is to equalize the pressure in the fuel tank. Without a vented cap or when the vent becomes plugged, the fuel tank will form a vacuum.

This will prevent fuel from flowing out of the tank. Without sufficient fuel flow, your Spartan zero turn will not start or run.

You may be able to identify if your gas cap is clogged by loosening or removing the cap and running your mower. If your mower starts and runs fine, replace the fuel cap.

Continue to let it run for a while to see if your mower dies because it is being starved of fuel. If your mower shuts off after a while and only starts when you remove the cap, there is a good chance your cap is bad.

Solution: When the fuel cap is not venting, replace it with a new Spartan fuel cap.

Bad Spark Plug

A fouled spark plug, incorrect gap, or loose wire can cause your Spartan mower’s starting problem. Your mower requires good spark to start. Any of these items can cause your spark plug to fire intermittently so your mower won’t always start.

Solution: Remove your spark plug using a socket wrench. Look for wear and damage including cracked porcelain, burnt electrode, or dirty plug. A damaged or excessively dirty plug that is dark in color must be replaced.

Otherwise, if it’s just a little dirty, you can clean it with a wire brush. I usually just replace the spark plug. It is an inexpensive part crucial to keeping your mower running at its best.

Before installing the plug, make sure the spark plug is gapped to the engine manufacturer’s specification. Install the spark plug and securely attach the spark plug wire to ensure it is making a good connection.

Clogged Air Filter

Operating a zero-turn stirs up a lot of dust and debris. It’s important to always run an air filter in your Spartan mower to avoid engine damage. Because of these dirty conditions, the air filter can become plugged when it isn’t regularly removed, cleaned, or replaced.

A plugged air filter restricts the amount of air that is able to get to the engine. A lack of air will prevent your Spartan mower from starting.

It can also cause damage to the engine if you run your mower with a very dirty filter due to overheating. Never run your Spartan mower without an air filter, even if it’s only for a short period of time while you finish your mowing task.

Solution: I recommend starting each mowing season with a new air filter. Your air filter maintenance doesn’t stop here.

You must check and clean it several times throughout the mowing season. The dustier the mowing conditions, the more often you need to check and clean your air filter.

Clean a Spartan mower paper air filter:

• Remove your filter from the air filter housing.
• Wipe out any dirt remaining in the housing with a dry clean rag. Don’t allow dirt to fall into the air intake.
• Tap your air filter against a solid surface. Knock as much dirt out of the filter as you can get loose. Don’t use compressed air to clean your filter as this will damage a filter.
• Check for light shining through the paper filter element by holding it up to a light source.
• If you can see light through the paper, reuse the air filter. If you can’t, replace the filter with a new one.
• Install your air filter in the housing and reattach the air filter housing cover.

Plugged Fuel Filter

A fuel filter is used to strain fuel coming out of the fuel tank to remove dirt and other contaminants from the fuel. The filter can become clogged if you haven’t changed the fuel filter regularly or are running very dirty gas.

A plugged fuel filter will prevent a steady flow of fuel from passing through the filter keeping your mower from starting. It is good practice to replace the fuel filter annually. If you end up running dirty fuel through your mower, you may need to change it sooner.

Solution: A clogged fuel filter must be replaced with a new one. When installing a new inline fuel filter on your Spartan zero turn, make sure the arrow on the side of the filter is pointed in the direction of the fuel flow.

Clogged Fuel Line

Bad or old fuel can cause clogging and damage throughout your fuel system. This includes the fuel lines as well.

You are not able to visibly see a clog in your fuel lines so you’ll have to check your hose by starting and stopping fuel flow using the fuel shut-off valve or pinch-off pliers to crimp your fuel line.

With your fuel flow stopped, remove one end of a section of the fuel hose (the end furthest from the fuel tank) and place it into a container. Make sure the container is placed lower than the fuel tank.

Fuel cannot flow uphill. Start your fuel flow and check to fuel coming out of the hose you placed in the container.

Solution: Once you find a clogged line, you need to try to remove the blockage. Do this by stopping the fuel flow and removing the line from your Spartan mower. Spray carburetor cleaner into the line to help loosen the blockage.

Then use compressed air to blow air into the line to remove the blockage. Repeat this process until the clog is removed. If you are unable to dislodge the clog, you will need to replace your fuel line.

You can purchase a mower fuel line at your local hardware store or online. I do recommend replacing your fuel line if the fuel lines are dry and beginning to crack even if you don’t find a clog.

Bad Fuel Pump

A fuel pump can fail over time. Old gas sitting in your fuel pump can degrade it causing it to fail. The fuel pump will no longer be able to draw fuel from the fuel tank using the vacuum of the engine.

When the fuel isn’t able to get to the carburetor, your Spartan mower will not start.

Check for leaks on your fuel pump. If you don’t find a leak, you will need to perform a couple of tests to make sure your fuel pump is operating properly. To do this, first, verify you are getting fuel to the pump.

Once you have verified you are getting flow to the pump, check to make sure fuel is being pumped out of the fuel pump. Do this by disconnecting the fuel hose from the carburetor and placing it in a container. Start your mower and watch the hose for a constant or pulsating fuel flow.

Solution: Replace your Spartan mower fuel pump if you are not receiving a constant or pulsating flow out of the pump.

Dirty Carburetor

Old fuel running through your Spartan mower can cause the carburetor to fail to function properly because deposits are left behind that clog the fuel jet and gum up the small components.

The carburetor’s purpose is to regulate the amount of gas mixed with air to create a combustion in the engine.

When the carburetor can’t function right, it will affect the Spartan mower’s ability to start and run. It must be disassembled and cleaned to remove gummy and crusty buildups.

Solution: If you are a little mechanical you should be able to handle disassembling the small parts in your carburetor to clean your Spartan’s carburetor.

If you are unsure about cleaning your own carburetor, you can have your local small engine mechanic clean your carburetor or you can replace it with a new carburetor.

Clean the carburetor by taking it apart and using carb cleaner to clean the carburetor including the float bowl and needle. You can find steps for cleaning your carburetor here. If your carburetor is too dirty to clean adequately, you should replace it.

Bad Battery, Loose Cables, or Corroded Terminals

Your Spartan will not start with a bad battery that won’t charge or fails to hold a charge. Loose cables or corroded terminals can also contribute to staring problems. Confirm your battery terminals are not corroded and are attached securely to the battery.

Solution: Clean corroded terminals in a baking soda solution containing 2 cups of water and 3 rounded tablespoons of baking soda. Use a wire brush to scrub the terminals clean.

Test your battery with a multimeter. You will want a reading at about 12.7 volts. Place on a charger to charge your battery if your reading is less than this.

Read more about the steps and items needed to charge your battery here. If your Spartan mower battery does not hold a charge, you will need to replace it with a new battery. 

Faulty Safety Switch

Your Spartan lawn mower uses several safety switches designed to keep the operator safe. The manufacturer installs safety switches to prevent your mower from starting without your parking brake engaged and the levers in the open/outward position.

It also has a safety switch that disengages your mower deck and shuts off your mower if it no longer senses the operator is present. You may have additional safety switches on your Spartan zero-turn. When these switches fail, your mower will fail to start.

Solution: Test a safety switch using a multimeter. You can temporarily bypass the safety switch to identify a bad switch but only do this for troubleshooting purposes.

Never operate a mower without the safety switch. Never run a mower when a safety switch is bypassed. A safety switch can save you from serious injury and you never know when you’re going to need it.

Bad Ignition Switch

You insert the key into your ignition switch and turn it only to find your Spartan doesn’t start or even turn over. The ignition switch could be the problem.

Solution: You can use a multimeter to test the ignition switch. Replace the switch if bad.

Faulty Charging System

While the charging system isn’t the main reason your Spartan lawn mower won’t start, it can contribute to a weak battery. The charging system is important to keep your battery charged.

If you find your battery keeps dying and you have to keep placing it on a charger, you may have problems with the charging system. When a component of this system fails, your Spartan mower will not start because the battery will not provide enough power.

A bad charging system can cause your battery to be drained preventing it from starting the next time you go to use your mower. A bad stator or alternator can be a problem. I show steps on how to test your charging system here.  

Solution: Have your local Spartan mower dealership or lawn mower small engine repair shop check your charging system to isolate the problem. If you don’t have experience with charging systems, you will most likely just be replacing electrical items until you find one that works.

This can get very expensive because most parts stores won’t let you return electrical parts if you find a part your purchased doesn’t resolve your starting problem.

If you don’t go to a Spartan dealership for support, make sure the mechanic you select has experience with charging systems or you’ll end up paying him or her to throw parts at your mower until the fix is found.

Incorrect Operating Procedure

Spartan mowers have starting procedures that need to be followed when starting and operating the lawn mower. If they are not followed, the mower may not start.

In addition to these items that are put in place for your safety, the mower may not start when the choke lever is not set correctly.

The choke is used to start a cold engine. The choke reduces the amount of air allowed into the cylinder so a higher ratio of fuel to air is ignited in the cylinder. The choke should be adjusted to the off position once your engine gets warm or your zero-turn will sputter and die.

Solution: Refer to your Spartan mower operator’s manual to ensure you are operating your lawn mower correctly, so you don’t set off the safety features that shut off your lawn mower.