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8 Reasons Your Riding Mower Won’t Start (Lawn Mower Starting Problems)

by Jack Grover
person riding lawn mower
Reading time: 18 min Prefer to listen?

When the sun is shining and the grass is growing, you might conclude it’s time to ride your trusty mower for a spin around the yard. Unfortunately, a malfunctioning mower can put a damper on your plans.

Lawn care equipment is quite intricate, with many components working together to ensure a smooth operation. The slightest issue with any of these parts can lead to starting problems or even larger mechanical failures.

This article provides valuable information, enabling you to diagnose and fix the issues yourself or make an informed decision when seeking professional assistance.

Whether you’re a seasoned lawn care expert or a first-time homeowner just getting started with maintaining your outdoor space, our insights will prove invaluable in keeping your riding mower in tip-top shape for years to come.

Let’s dive right in and explore why your riding mower won’t start and the best methods to get it up and running again.

Dead or Weak Battery

One of the most common reasons for a riding mower not starting is a dead or weak battery.

The battery is the primary power source for the starter motor, which is responsible for cranking the engine. If the battery lacks sufficient power, it won’t be able to energize the motor, preventing your mower from starting.

You can perform a few simple checks to determine whether the battery is the root cause of your starting problem.

Begin by inspecting the battery terminals for signs of corrosion. Corroded terminals can impede the flow of electricity from the battery to the starter motor. At the same time, check for loose connections since they may result in intermittent power transfer.

You can also measure the battery’s voltage. A fully charged battery should register around 12.6 volts.

If your reading is below 12 volts, your battery may not have enough charge to turn the starter motor. In this case, you have two options: either recharge the battery using a suitable charger or consider replacing it if it’s old and no longer holding a charge effectively.


  • If your battery terminals are corroded, clean them with a wire brush.
  • When you notice your connections are loose, tighten them.
  • Use a multimeter to measure the battery’s voltage. If your battery’s voltage is low, recharge or replace it.
black and red digital device

Faulty Ignition Switch

The ignition switch, a crucial component in your riding mower’s electrical system, serves as the bridge between the battery and the starter motor. Its primary function is to transmit an electric current from the battery to the starter motor once you turn the key.

This process sets in motion a series of events that ultimately allow your mower’s engine to roar to life.

However, if the ignition switch malfunctions or becomes faulty, it can interfere with this chain of events and prevent your riding mower from starting at all.

A faulty ignition switch may stem from various factors, such as:

  • wear and tear,
  • corrosion,
  • or damage sustained from external elements.

Regardless of the cause, a malfunctioning switch can leave you stranded and unable to tend to your lawn.

To avoid such a frustrating situation, it is vital to conduct periodic checks on your mower’s ignition switch and address any issues as soon as they appear.

Before examining the ignition switch itself, make sure you have engaged all safety mechanisms correctly. Check if the parking brake is set and the blade engagement lever is disengaged.

Once you’ve verified that all safety mechanisms are in place, you can test the ignition switch.

Use a multimeter to check for continuity between its terminals while turning the key. If there is no continuity or the readings are inconsistent, it’s an indication the switch is malfunctioning and may need replacement.


  • Test the ignition switch with a multimeter by checking for continuity between its terminals while turning the key. If there’s no continuity, it’s time to replace the switch.

Dirty Carburetor

The carburetor plays a vital role in your mower’s engine performance by mixing the right amount of air and fuel for optimal combustion. Over time, dirt, debris, and old fuel can accumulate in the carburetor, causing clogs and affecting the engine’s ability to start or run smoothly.

A dirty carburetor can lead to fuel flow problems, which, in turn, can prevent your riding mower from starting.

If your mower has been sitting idle for an extended period, there’s a possibility the old fuel in the carburetor may have evaporated, leaving behind a sticky residue called varnish. This residue can obstruct fuel passages and cause starting issues.

Moreover, any dirt or debris that finds its way into the carburetor can also contribute to these obstructions.

To address this issue, you’ll need to clean the carburetor thoroughly. Here’s a step-by-step instruction on how to do it.


  1. Remove the carburetor from the engine by disconnecting the appropriate linkage and hoses.
  2. Disassemble the carburetor carefully, taking note of the positions of all components to ensure proper reassembly.
  3. Use a carburetor cleaner to clean each part, removing any dirt, debris, or varnish that may have accumulated. Pay close attention to small fuel passages and jets, as these areas are most prone to clogging.
  4. After cleaning all the components, inspect the gaskets for signs of wear or damage. If necessary, replace them with new ones to ensure a proper seal when reassembling the carburetor.
  5. Reassemble the carburetor and reinstall it onto the engine.

Clogged Fuel Filter

A lawn mower’s smooth operation relies heavily on the efficient flow of fuel to the engine. The fuel filter is indispensable for this process, keeping impurities and debris from entering the engine.

Over time, however, the fuel filter can become clogged with these particles, impeding fuel flow and preventing your lawn mower from starting.

When you suspect a clogged fuel filter might be the culprit behind your lawn mower’s starting problems, inspect it for signs of blockage or damage. Discoloration or visible debris within the filter are clear indicators it may be time for a replacement.


Replacing a clogged fuel filter is a quick and straightforward process.

  1. Consult your owner’s manual for specific instructions on locating and accessing the fuel filter on your particular lawn mower model.
  2. Once you’ve identified its location, turn off the fuel valve (if equipped) or use a fuel line clamp to prevent leakage during the replacement process.
  3. Carefully remove the old fuel filter, paying attention to the direction of the fuel flow marked on it.
  4. Before installing the new fuel filter, inspect the fuel lines for signs of damage or wear. Cracked or deteriorated fuel lines can contribute to starting problems and should be replaced if necessary.
  5. Install the new filter with the correct orientation to ensure proper fuel flow.
  6. Finally, turn on the fuel valve or remove the fuel line clamp and check for any leaks around the newly installed filter.

Remember that regularly changing your fuel filter according to the manufacturer’s recommendations can prevent future clogging issues and prolong the life of your lawn mower.

Damaged Starter Motor

grayscale photo of person playing piano

The starter motor is responsible for turning the engine over when you engage the ignition. In other words, it sets the engine’s internal components in motion, allowing it to fire up and run smoothly.

If your starter motor is damaged or compromised in any way, it might not have enough power to crank the engine effectively. Consequently, your mower will be unable to start.

There are several telltale signs your starter motor may be at fault. For example, if you hear a clicking sound when turning the key but the engine fails to crank, this could be indicative of a malfunctioning starter motor.

Additionally, if you notice intermittent starting issues or sluggish cranking, these symptoms could also point toward a problem with the motor.

You must follow a systematic approach to diagnose and remedy a damaged starter motor.

Firstly, inspect all connections between the battery and the starter motor. Ensure they are clean, free of corrosion, and securely fastened. Loose or corroded connections can impede the flow of electricity, resulting in insufficient power reaching the starter motor.

If the connections appear to be in good condition, test the starter motor itself. Using a multimeter, measure the voltage at the starter motor terminal while attempting to start the mower.

A healthy starter motor should receive close to 12 volts during cranking. If the voltage is significantly lower, there could be an issue with the wiring or another electrical component in the starting system.

In some cases, the internal components of the starter motor may wear out over time, leading to reduced performance or complete failure. If you suspect this to be the case, it’s best to consult a professional mechanic for further diagnosis and potential starter motor replacement.

Replacing a damaged starter motor can be a complex task, particularly for those with limited mechanical experience. Therefore, seeking professional assistance is highly recommended.


  • Check for any loose or corroded connections between the battery and the starter motor. Tighten or clean them as needed.
  • If you hear a clicking sound when turning the key, but the engine doesn’t crank, it could indicate a faulty starter motor. In this case, you may need to replace it.

Empty Fuel Tank

It might sound obvious, but an empty fuel tank is a common reason why a riding mower won’t start. Sometimes, we can become so focused on more complicated issues that we overlook the simplest ones.

We dive into the nitty-gritty, dissecting every possible component, utterly convinced there must be a complex explanation for the sudden halt in our lawn-care endeavors.

Yet, the truth is often far simpler than we’d care to admit.

So, before you embark on an epic quest to uncover the hidden secrets of your unresponsive mower, pause for a moment and inspect that fuel tank. You may just save yourself a world of frustration and unnecessary tinkering.


  • Before attempting to start your mower, check the fuel level in the tank. If it’s empty or nearly empty, refill it with fresh fuel according to your mower’s specifications.
  • Regularly monitor your fuel levels and refill as needed to avoid running out of gas unexpectedly. Keeping a small reserve of fuel in a well-ventilated storage area can be helpful for those times when you need to top up quickly.

Wrong Type of Gas

Using the wrong type of gasoline in your riding mower is yet another thing that can lead to starting issues.

But it’s not just about short-term inconvenience; long-term consequences are also at stake.

By using the wrong type of gasoline, you could unknowingly cause damage to your mower’s engine. This damage can accumulate over time, eventually leading to costly repairs or complete engine failure.

No one wants their trusty mower to meet such an untimely demise.

So how do you ensure optimum performance and maintain the life of your mower’s engine? The answer lies in using the correct fuel.

Most riding mowers are designed to run on regular unleaded gasoline with an octane rating of 87 or higher. Still, always consult your owner’s manual for the manufacturer’s recommended fuel type.


  • Avoid using gasoline containing more than 10% ethanol (E10). Higher ethanol blends, such as E15 or E85, can cause corrosion and damage to the fuel system components over time.
  • Check the fuel in your mower’s tank for any signs of contamination or separation. If you suspect that you’ve accidentally filled it with the wrong type of gas, drain the tank and refill it with the correct fuel before attempting to start the engine.

To avoid future issues related to using the wrong type of gas, always double-check the fuel you’re using before filling your mower’s tank. Keep a dedicated fuel container for your lawn equipment to prevent accidental mix-ups.

Bad Safety Switch

Safety switches, also known as interlock switches, are designed to keep you safe while operating your riding mower. These switches ensure the mower starts and runs under specific conditions, such as when you’re seated on the mower or when the blade engagement lever is disengaged.

A malfunctioning safety switch can prevent your riding mower from starting, even if everything else is working correctly.

Start by checking the seat safety switch. This switch ensures the mower will only start when someone is seated in the driver’s position. Inspect the connections and wires for any signs of damage or wear.

You can also test the switch with a multimeter by checking for continuity when pressure is applied to it (simulating someone sitting on the seat). If there’s no continuity, consider replacing the seat safety switch.

Next, inspect the blade engagement safety switch. This switch prevents the mower from starting if the cutting blades are engaged.

Check if the blade engagement lever is fully disengaged and look for signs of damage or wear to the connections and wires. Test this switch with a multimeter as well, looking for continuity when the lever is disengaged. Replace the switch if necessary.

Some riding mowers may also have additional safety switches, such as those connected to the parking brake or gear shift lever. Consult your owner’s manual for information on how to locate and test these switches.


  • Check the seat safety switch, blade engagement safety switch, and additional safety switches.
  • Inspect connections and wires for damage or wear.
  • Test with a multimeter for continuity.
  • Consult the owner’s manual for location and testing instructions.

Final Thoughts

No one enjoys dealing with a stubborn riding mower that refuses to start. Understanding these eight common causes of lawn mower starting problems can save you time, money, and frustration.

Remember to follow your mower’s maintenance schedule and consult the owner’s manual for specific troubleshooting tips for your particular model. Regular upkeep not only ensures optimal performance but also prolongs the lifespan of your equipment, making it a worthwhile investment in the long run.

By taking a proactive approach and addressing potential issues before they escalate, you can minimize downtime and maximize productivity when it comes to maintaining your lawn.

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