Kubota Zero Turn Mower Won’t Start for These 16 Reasons

Kubota produces a zero-turn tractor that can hold its own against the best of them. This is not to say that issues won’t arise.

Many other issues can prevent a Kubota zero-turn from starting, including a clogged fuel filter or line, a filthy carburetor, a faulty gas cap, a faulty spark plug, a faulty starter solenoid, a faulty switch, a dead battery, a clogged air filter, or the incorrect choke setting.

For more prompts, please keep reading. Follow all of the precautions listed in your Kubota’s manual to ensure your safety. Removing the spark plug wire(s) and waiting for the engine to cool down are two examples.

kubota mower

Before diagnosing, repairing, or operating, be sure you’ve read and understood all of the safety recommendations in the equipment’s operator’s manual.If you are unsure of how to proceed, lack the necessary expertise, or are unable to execute the repair properly, you should seek the advice of a professional.

What Causes A Dead Kubota Zero-Turn Mower

Kubota Zero Turn Mower with an Empty Gas Tank

In case you started looking at other parts of your Kubota zero-turn before remembering the gasoline tank, I’ll remind you to check it.

It’s possible you have a fuel leak, the fuel gauge is broken, or you just can’t remember the last time you refueled.

SOLUTION: Make sure there is no fuel leak by inspecting the fuel system. Fix or replace anything you find to be leaking or broken. Refill the gas tank with new fuel.

Misusing a Kubota Zero Turn with the Wrong or Old Gas

Fuel Specification for a Kubota Zero Turn Mower

For optimal performance, the mower requires clean, fresh fuel. When a Kubota zero-turn starts running slowly, won’t start, or dies after running, old gas is usually to blame.

Most modern gasoline contains ethanol, which has a hygroscopic effect on the fuel system and draws moisture from the air. Varnish and sticky residues may be left behind by the ethanol and water solution.

Because of this, fuel flow is restricted or parts break. If the gas flow to your Kubota is inadequate, it may be difficult to start.

Use only low-ethanol gas or fuel that is completely ethanol-free in a zero-turn vehicle, as ethanol can damage the engine and fuel system. Engine damage is possible from using gas with a high ethanol content.

Gasoline with an octane value of 87 or higher and no more than 10% ethanol is recommended for Kubota zero-turn mowers. Here you may learn how to determine which fuel is ideal for a Kubota zero-turn mower.

Kubota Zero Turn Mowers Must Have New Gasoline

It’s best to buy gas and use it up within 30 days, as after that point it starts to degrade and become less effective.

If you’ve bought more gas than you can use up in 30 days, you can extend its shelf life by using a gasoline stabilizer like Sea Foam Motor Treatment.

In a word, yes! It’s an extra layer of defense for the fuel system, therefore I put it in all of my small engine fuel. To learn more about its benefits, check visit Sea Foam is a great fuel stabilizer for your lawn mower.

If you realize you put old fuel in the tank or the wrong kind of fuel in it, the answer is to drain the tank. A manual siphon pump is a low-cost option that can efficiently drain the tank.

Refill the gas tank and use a fuel stabilizer to prevent the fuel from going bad.

Kubota Zero Turn Vehicle Fuel Filter Clogged

A Kubota zero-turn’s fuel filter cleans the fuel as it exits the tank, preventing debris and dirt from being sucked into the engine.

This filter needs to be changed once a year to keep working properly. If you discover that a fuel tank was particularly contaminated, you may need to change the filter more frequently.

You shouldn’t use the fuel if you find out it’s contaminated. In the event that fuel is already present in the tank, it should be drained.

A clogged fuel filter is the result of neglectful maintenance. The filter won’t be able to let enough gas through.

A new gasoline filter must be installed to fix a clogged one. Make sure the arrow on the filter faces the direction of gasoline flow when installing.

Kubota Zero Turn Tractor Fuel Line Clog

Old fuel can leave behind sticky deposits that might clog fuel lines. Because of this, gasoline flow through the line is stifled.

When a clogged line is located, the solution is to clear it out. Get started by cutting the line off your Kubota.

If the line is clogged, you can try spraying carburetor cleaner into it. Compressed air is blown into the pipe after the carb cleaning to dislodge the obstruction.

In the event that you are unable to remove the obstruction, you should invest in a new gasoline line, taking care to select one with the appropriate diameter and length. To get the length of line you need, you’ll have to snip it.

If your gasoline lines are dry and cracking, you should replace them even if you don’t detect a blockage in them.

A Kubota Zero Turn Mower’s Faulty Fuel Pump

It’s possible that the zero-turn’s fuel pump is what’s keeping it from firing up. The fuel pump is designed to overcome the force of gravity and lift fuel to the carburetor.

If it breaks, the gasoline supply to the carburetor will be interrupted, preventing the engine from starting. It’s possible for a carburetor to break down after some time has passed.

The fuel pump on most Kubota zero-turn mowers is a vacuum type. Fuel can deteriorate your fuel pump over time. If your fuel pump is no longer able to use engine vacuum to draw fuel from the tank, you’ll need to replace it.

The fuel pump has to be replaced if fuel is leaking from it. When there are no obvious indicators of damage to your pump, there are still a few tests you may run to determine if there is an issue:

  • The fuel shut-off valve can be found under the fuel tank, or you can use clamps to squeeze the fuel line and halt the flow.
  • Unplug the pump’s hose from its inlet. The fuel will flow into the container via gravity if it is placed below the fuel tank. Verifying the fuel pump is receiving fuel is the next step.
  • Get the gas going. If fuel is entering the container, you know the pump is receiving fuel. If you aren’t, then you need to find the fuel restriction before you fill up.
  • Stop the flow of fuel. Switch out the hose that leads to the inlet.
  • To inspect the fuel pump, take the hose off the carburetor and set it in a container.
    Turn on the gas and fire up the engine. Keep an eye on the gasoline line to see if there is a continuous or pulsing flow of fuel.
  • Turn off the lawnmower and reconnect the fuel hose to the carburetor once you’ve finished testing.

If the fuel flow from your Kubota is inconsistent or pulsing, you should replace the pump.

Unclean Carb on a Kubota Zero Turn Mower

Your Kubota zero-turn could not turn over if the carburetor is dusty. An inoperable carburetor prevents the engine from starting because it cannot control the ratio of air to fuel.

The failure of a carburetor is frequently attributable to stale fuel. This is because the gasoline channels become clogged with old fuel, reducing fuel flow. It can also leave a varnish that prevents moving parts within the vehicle from moving.

In the event that your carburetor is malfunctioning, you should clean it and replace any pieces that are stuck or too damaged to be cleaned.

Here is a SOLUTION: I detailed how to clean the carburetor on a Kubota lawnmower.If you have a basic understanding of mechanics and are confident handling small components, then follow these instructions.

Your local small engine repair shop should be able to clean or rebuild your carburetor if you don’t feel comfortable doing it yourself, or you can buy a new carburetor assembly for your mower.

A Kubota Zero Turn Mower with a Leaking Gas Cap

There must be a way for air to enter and leave the fuel tank. Without a vent, a vacuum accumulates inside the tank, preventing fuel from escaping and reaching the carburetor.

The fuel cap on a Kubota zero-turn mower acts as a vent, allowing the tank’s internal pressure to equal that of the surrounding air.

If your Kubota’s gas cap is faulty, you can test it by operating the machine with and without the cap. If your zero-turn won’t crank with the cap on, try taking off a few turns to let air into the fuel tank. Possible release of vacuum pressure.

Loosening the cap and trying to start the mower could indicate a gas cap venting issue.

If the mower suddenly turns off and won’t start again unless the fuel cap is loosened, try tightening the cap and running it again.

REMEDY: Swap out the gas cap on your Kubota zero-turn mower.

A Kubota Zero Turn Mower with a Faulty Spark Plug

Loose spark plug wires or an improperly adjusted gap can cause your zero-turn to have starting and operating problems. Intermittent spark difficulties might also be caused by dirty spark plugs.

If you’re having trouble starting your zero-turn, check the spark plugs to be sure the problem isn’t there.

Pull out the spark plug and check for carbon buildup or a broken porcelain insulator.If the spark plug(s) are damaged, worn, or particularly dark in color, you should replace them.

The tip of the spark plug(s) should be cleaned using a fine wire brush to ensure proper operation. Check the gap on the spark plugs and the connections of the wires.

Kubota Zero Turn Tractor Clogged Air Filter

A dirty air filter doesn’t just prevent your engine from getting the clean air it needs; it also lets dirt and debris into the cylinder, where it can do serious damage.

If the air filter gets clogged, less air reaches the engine. A Kubota might not start, the engine might overheat, and smoke might come out.

The air filter should be changed once a year and its condition should be monitored frequently throughout the mowing season. Clean the filter if you find it to be in good working order. However, if it is extremely soiled or broken, it is recommended that you get a new one.

The answer is simple: just clean the filter. If a clogged air filter is preventing your Kubota from starting, try replacing it.

Cleanse a Kubota paper air filter:

  • Take off the actual air filter from its housing.
  • Keep the air filter free of debris. Use a dry cloth to remove any lingering debris from the filter housing and filter cap.
  • To remove as much dust and debris from the air filter as possible, tap it against a hard surface.
  • Examine the paper element of the filter by holding it up to a light.
  • If the filter allows you to see, keep using it. If the filter is damaged, severely soiled, or opaque, you should get a new one.
  • Put the air filter in place.

A Kubota Zero Turn Mower with Loose Cables or Corroded Terminals, Wiring, or Components

Corroded electrical components, wires, and terminals can prevent a zero turn from starting, along with loose cables.

Solution: Get rid of the rust and corrosion. First, take off the rusted parts and then reconnect the battery.

To get rid of the rust, grab a tiny metal brush and either cola or a baking soda solution (2 cups of water mixed with 3 heaping tablespoons of baking soda).

Then, double check the connections and wiring to ensure everything is in place and working properly.

Kubota Zero-Turn Tractor with Weak or Defective Battery

A Kubota zero-turn that requires a lot of power to start won’t turn over with a poor battery. A new battery should be used if the old one can’t maintain a charge.

A multimeter check should be performed on your zero-turn battery. Put the battery on a charger if the voltage is below 12.7 volts. Find out what you’ll need to know about how to charge the battery in your Kubota tractor.

Kubota Zero Turn Mower Faulty Safety Switch

The safety features of your zero-turn mower include an operator presence control system. Your zero-turn may not turn over because of a faulty safety switch.

Use a multimeter to check the functionality of your switches. As a troubleshooting measure, you can try briefly disable a safety switch to see if the problem persists.

Never cut grass without first flipping the mower’s safety switch.Mowers should never be used if the safety switch has been removed. You never know when you might need a safety switch, but having one is always a good idea.

Kubota Zero Turn Tractor Faulty Ignition Switch

When turning the key but getting no response, the ignition switch may be at fault.

The ignition switch can be tested with a multimeter. If the switch is broken, replace it.

Kubota Zero Turn Tractor Faulty Starter Solenoid

The electromagnetic “on/off” switch of a lawnmower solenoid activates the starter motor to get the engine cranking. Check the solenoid if you hear a click or hum when you turn the key in the ignition.

If a wire leading to your solenoid overheats and smokes or melts, there’s another red flag that something is wrong.

Follow these instructions to check the solenoid in your Kubota. If your solenoid is faulty, you should replace it.

Kubota Zero Turn Faulty Charging System

A poor battery isn’t always the reason a Kubota zero-turn mower won’t start, but if the charging mechanism isn’t working properly, it could be a contributing factor.

When the battery isn’t fully charged, the mower won’t start. This might happen if the charging system malfunctions.

Several other electrical components, including a faulty stator or alternator, could be at fault. If you have an ohm meter and want to make sure your charging system is working, read this page.

Once you’ve determined that your charging system is malfunctioning, I recommend taking your mower to a certified Kubota zero-turn mower service center for repair.

The charging system consists of a wide variety of parts. If you don’t know what you’re doing, you’ll probably just start throwing components at your mower in the hopes of finding the one that breaks.

The cost of your lawnmower’s electric components can add up quickly. Electric components are almost certainly final sale. Therefore, you will be left with the costly component even if it turns out to be unnecessary.

Incorrect Choke Setting/Operating Procedure for Kubota Zero Turn

In order to get your zero-turn going, you’ll need to follow a few different starting techniques.

The Choke Needs to Be Adjusted

When trying to start a cold engine, you should tighten the choke. The mower won’t start if the choke lever isn’t in the correct position.

How to Fire Up a Chilly Kubota Zero-Turn:

  • Adjust the choke to its tightest setting.
  • Set the throttle’s position to midway between slow and quick.
  • Put the key in the “start” position and pull it out when the motor fires up.
  • Put the choke off by moving the lever to the left.
  • For the first few minutes of mowing, let the engine warm up at half throttle.

The Kubota safety interlock system should not be activated in any way.

The purpose of the safety interlock mechanism is to protect you. If you don’t meet the safety criteria for operating the mower, your Kubota won’t turn on.

Before initiating a zero-turn, make sure the following safety conditions are met:

  • Take a seat in the driver’s seat.
  • To make sure the brake is on, engage it.
  • Turn off paid time off.

SOLUTION: Use the aforementioned procedures to get your Kubota zero-turn mower going. This includes making sure the choke is set properly and following all other safety precautions before attempting to start the engine. Refer to the owner’s manual for your mower’s make and model for instructions on how to start it.