8 Common Causes of Failed Lawnmower Starts

When the weather is nice and the grass is flourishing, you might decide to take your mower out for a spin. Unfortunately, your intentions may be derailed if your mower breaks down.

Complex mechanisms and interlocking parts are what make lawn care machinery so reliable. Any fault at all with any of these components can cause starting issues or even catastrophic mechanical breakdown.

If you’re having trouble diagnosing or fixing the problem, you may use the information in this article to either do it yourself or make a more educated decision about whether or not to seek expert help.

Our advice can help you keep your riding mower in great form for years to come, whether you’re a seasoned lawn care expert or a first-time homeowner just getting started managing your outdoor space.

Let’s jump right in and investigate the causes of your riding mower’s inability to start, as well as the most effective solutions for getting it going again.

lawn mower

The Battery Is Weak or Dead

A dead or weak battery is a typical cause of a riding mower not starting.

The starter motor, which turns the engine’s crankshaft, receives its power primarily from the battery. Your lawnmower won’t turn over if the battery isn’t strong enough to supply enough juice to the motor.

If you’re having trouble getting your vehicle to start, a quick battery test can tell you for sure.

First, look for rust on the battery terminals. Terminal corrosion might prevent power from reaching the starter motor from the battery. Also, make sure there are no sloppy connections that could cause power fluctuations.

The battery’s voltage can also be checked. In the region of 12.6 volts, a completely charged battery should read.

If your battery’s voltage falls below 12 volts, the starter motor may not turn. If the battery is old and no longer holds a charge well, you can either charge it using a proper charger or replace it.

The Ignition Switch Is Broken

The ignition switch connects the battery to the starter motor of your riding mower and is thus an essential part of the electrical system. When the key is turned, it transfers electricity from the battery to the starter motor.

This action triggers a chain reaction that causes the engine on your lawnmower to start up with a roar.

Nevertheless, if the ignition switch is broken or becomes faulty, it might disrupt this sequence and make it impossible for your riding mower to start.

Many things can lead to a malfunctioning ignition switch, including:

A broken switch, regardless of its origin, will prevent you from taking care of your lawn.

Checking the ignition switch on your mower on a regular basis and fixing any problems that you find immediately can help you prevent a difficult situation like this.

Make sure that all safety features are activated before checking the ignition switch. Verify that the blade engagement lever is not engaged and the parking brake is set.

After making sure everything is secure, you can try the key cylinder.

Turn the key while checking for continuity between the terminals with a multimeter. It’s possible the switch is broken and has to be replaced if there’s no continuity or if the readings don’t match up.

Unclean Carburetor

The efficiency of the engine of your lawnmower depends on the carburetor’s ability to blend the correct quantities of air and fuel for combustion. Clogs in the carburetor from dirt, debris, and old fuel can make it difficult for an engine to start or function efficiently over time.

A clogged or dirty carburetor might prevent fuel from flowing properly, making it impossible to start your riding mower.

When a lawnmower is left idle for a long time, the old fuel in the carburetor can evaporate, leaving behind a varnishy residue. This residue can clog fuel lines, making it difficult to start the engine.

And any dirt or debris that makes its way into the carburetor might add to the blockage.

Cleaning the carburetor carefully should fix the problem. Here is a detailed guide on how to do the task.


  • Disconnect the carburetor’s hoses and linkage before removing it from the engine.
  • Carefully remove the carburetor’s parts, marking their locations for further reference.
  • If dirt, debris, or varnish has built up on any of the components, a carburetor cleaner can help you get rid of it. Pay particular attention to the fuel jets and smaller fuel tubes, since these are the most likely to become clogged.
  • Check the gaskets for damage or wear after you’ve cleaned everything else. When reassembling the carburetor, use new gaskets if the old ones have worn out.
  • Carburetor reassembly and re-engineering are in order.

Stuck Fuel Filter

The efficient delivery of gasoline to the mower’s engine is crucial to its reliable performance. In order to prevent debris and contaminants from entering the engine, a gasoline filter is essential.

However, these particles can accumulate in the fuel filter over time, blocking gasoline flow and making it impossible to start your lawn mower.

If you are having trouble starting your lawnmower and think a blocked fuel filter may be to blame, check it out. If the filter begins to discolor or has visible debris, it may be time to replace it.

It’s easy and fast to change a blocked fuel filter.

  • Read the manual that came with your lawnmower to learn where and how to access the fuel filter.
  • Locate the fuel shutoff valve (if present) or a fuel line clamp to prevent fuel from leaking while you replace it.
  • When replacing the fuel filter, make sure you remove it carefully and in the correct direction.
  • Check for damage or wear in the fuel lines before installing the replacement fuel filter. Replacement of fuel lines that are worn or cracked is recommended if starting issues persist.
  • Ensure adequate fuel flow by installing the replacement filter in the correct orientation.
  • Finally, after installing the filter, you should switch on the fuel valve or loosen the fuel line clamp to look for leaks.

To avoid future clogging issues and to extend the life of your lawn mower, remember to regularly replace the fuel filter as directed by the manufacturer.

Broken Ignition Motor

When the ignition is turned on, the starter motor spins the engine’s crankshaft. That is to say, it activates the engine’s inner workings, resulting in a successful ignition and subsequent operation.

It’s possible that your starter motor won’t have the strength to properly crank the engine if it’s been damaged or compromised in any way. As a result, you will have trouble starting your lawnmower.

There are a number of warning signals that indicate your starter motor could be malfunctioning. If the engine doesn’t crank when you turn the key, but you hear a clicking sound, the problem may be the starter motor.

There may be an issue with the motor if you additionally have sluggish cranking or random starting problems.

Repairing a malfunctioning starting motor requires a methodical procedure.

First, make sure the battery is properly connected to the starter. See to it that they are spotless, rust-free, and firmly attached. If the electrical connections are loose or rusted, not enough current will flow to the starter motor.

If the wires don’t appear to be frayed, the starter motor should be tried. Check the starter motor terminal voltage using a multimeter when you try to start the mower.

During cranking, the voltage delivered to a good starter motor should be close to 12 volts. A problem with the wiring or another electrical part of the starting system is possible if the voltage is noticeably lower than normal.

Wear and tear on the starter motor’s internal components can eventually cause it to operate less efficiently or stop working altogether. If you have any reason to believe this is the case, you should take your car to a mechanic to be checked out and possibly have the starter motor replaced.

Fixing a faulty starting motor is not a simple job, especially for people without much expertise working on cars. Therefore, it is strongly suggested that you get some expert help.

No Gas in the Tank

A typical cause of a riding mower not starting is an empty fuel tank. It is easy to lose sight of the obvious in favor of worrying about the more complex concerns at hand.

We get down to brass tacks, examining each and every part, confident that the sudden halt in our lawn-care efforts must have a convoluted explanation.

The reality, though, is typically much more straightforward.

So, before you go on a daring adventure to solve the mystery of your non-working lawnmower, take a break and check the gas tank. You could end up sparing yourself a lot of hassle and pointless fiddling if you take this advice.

Incorrect Gas Type

Another common cause of riding mower refusal to start is the use of the incorrect fuel type.

It’s not just an inconvenient situation right now; there are long-term repercussions at risk as well.

Using the incorrect type of gas might damage your lawnmower’s motor without you even realizing it. Over time, this wear and tear can add up, necessitating expensive repairs or even total engine failure.

No one wants to see their mower go out in such a tragic way.

How then can you prolong the life of your mower’s motor and keep it performing at peak efficiency? The key is to use the right kind of fuel.

Regular unleaded gasoline with an octane value of 87 or higher is recommended for most riding mowers. However, before you fill up, check your owner’s manual to see what the manufacturer suggests.

Always double-check the gasoline you’re using before filling your mower’s tank to avoid future problems due to using the wrong sort of gas. To avoid any confusion, always store lawn equipment gasoline in a separate container.

Defective Safety Switch

Safety switches, often called interlock switches, are installed in riding mowers for the operator’s protection. If you’re not seated on the mower or the blade engagement lever isn’t in the off position, the mower won’t start or run.

Even if everything else is in working order, your riding mower won’t start if the safety switch is broken.

The seat safety switch should be checked first. Having someone in the driver’s seat is required for the mower to start, so this switch prevents accidental ignition. Check the wires and plugs for fraying or other wear and tear.

Applying pressure to the switch (to mimic a person sitting on the seat) and checking for continuity with a multimeter is another way to validate its functionality. The seat’s safety switch should be replaced if the circuit is broken.

The safety switch for the blades should then be checked. If the mower’s blades are already spinning when the switch is flipped, the engine will not start.

Look for signs of wear and tear on the wires and connections, and make sure the blade engagement lever is in the “off” position. Also, use a multimeter to check for continuity when the switch is disengaged and the lever is moved to the off position. If the switch has to be replaced, do so.

Additional safety switches, such as those for the parking brake and gear shift lever, may be found on some riding mower models. Find out where these switches are and how to check them by consulting your manual.


Having to struggle with a riding mower that won’t start is a hassle nobody wants to go through. To avoid wasting time, money, and energy, research the eight most common reasons why your lawn mower won’t start.

Don’t forget to perform regular maintenance on your mower and to check the manual for any model-specific troubleshooting advice. Maintaining your equipment on a regular basis will not only keep it running smoothly, but will also extend its useful life, making it a better investment in the long term.

Taking preventative measures and fixing small problems before they become big ones will help you keep your lawn looking great while getting the most work done.