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16 Reasons Your Simplicity Lawn Mower Won’t Start

It’s that time again when your lawn needs to be mowed, but unfortunately, your Simplicity mower will not start. The grass doesn’t stop growing and bringing your mower to your local repair shop during mowing season can take forever to get back.

What can you do? There are some starting issues that you can easily fix to avoid the long wait.

A Simplicity lawn mower will not start when it isn’t getting sufficient fuel, air, or spark due to a plugged air filter, fuel clogs, a dirty carburetor, a faulty fuel pump, dirty spark plugs, bad ignition coil, or bad starter solenoid. A bad charging system or incorrect starting procedure can also keep your Simplicity mower from starting.

Follow the safety instructions in your Simplicity owner’s manual to prevent injury while working on your lawn mower.

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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 Simplicity Lawn Mower Won’t Start

No Gas in Your Gas Tank 

You know your Simplicity mower won’t run when you don’t have gas in the tank. Even though this is an obvious fact, it can be overlooked during the heat of the moment when you’re frustrated because you can’t get your mower to start.

Running out of gas can simply be due to overlooking your fuel levels and forgetting to refill the tank. It can also be the cause of going through more fuel than normal because you developed a fuel leak you are unaware of.

Fix: Fill your gas-powered mower with fresh gasoline with an octane rating of 87-grade or higher. Choose the right kind of gas with an ethanol level no greater than 10%.  

Bad or Old Fuel

Running gas that’s been sitting in your lawn mower or stored in your garage for a long time can cause damage to your fuel system. Old gas becomes less effective as quickly as 30 days after purchase and begins to break down.

Ethanol and the moisture it attracts will separate from the gasoline sinking to the bottom of the tank. This solution runs hot which can cause damage to your engine.

It will also cause corrosion of the fuel system and evaporate leaving behind a gummy residue creating blockages in the fuel system.

It is necessary to purchase fuel from a busy gas station and use it within a 30-day time period.

If you are unable to consume the fuel this quickly, don’t worry, you can use a fuel additive like Sea Foam Motor Treatment to stabilize the fuel. Read more about the advantages of adding Sea Foam to your gas here.

Fix: Remove the old fuel using a fuel siphon and add fresh fuel. 

Faulty or Clogged Gas Cap 

Your gas cap is designed with a vent to allow air to pass through the cap. When this vent gets plugged, the fuel tank will create a vacuum preventing your Simplicity mower from drawing gas out of the fuel tank. 

You can identify a fuel tank cap problem by running your mower with and without the cap. If it starts and runs without the fuel cap, but dies after you let your mower run with the fuel cap on for a while, you most likely have a cap problem.

Fix: Replace with a new fuel cap. You can find one online or visit your local Simplicity dealership. 

Bad Spark Plug or Loose Connection

Another reason your Simplicity mower won’t run may be due to a bad spark plug connection or a damaged spark plug. A plug that has carbon buildup, burnt electrodes, or cracked porcelain can fail and cause your engine to misfire. 

Fix: Remove your spark plug and inspect it for signs of carbon buildup or cracked porcelain insulators. You can attempt to clean the plug with a wire brush.

Replace with a new spark plug(s) if you find it is dark in color, has broken porcelain, or burnt electrodes. Make sure to gap them according to manufacturer specifications and that your spark plug wires are securely in place.

Plugged Air Filter

When the air filter in your Simplicity lawn mower gets extremely dirty, it can starve the engine of air causing the mower to not start. Not only can a plugged air filter prevent the mower from starting, but even if it does start, it can also cause your Simplicity to overheat.

Fix: Clean a paper air filter by removing it from the air filter housing. Take caution when removing it to ensure you are not dropping any loose dirt into the air intake. You will need to wipe out any remaining dirt in the housing with a clean dry cloth.

Knock the excess dirt out of the filter by tapping it against a hard surface. Do not use an air compressor to clean the air filter.

Once you have gotten as much dirt out of the filter as possible, hold it up to the light to see if you are able to see light shine through the paper. If you can, you can reuse the filter. If you cannot, you must replace the filter.

You can find information on other types of air filters and how to clean them here

Bad Fuel Pump

The fuel pump exists to pump fuel to the carburetor. When the fuel tank sits below the carburetor a pump is needed to help move the gas. A fuel pump, just like any other mechanical part, can fail over time. A likely cause is due to old fuel deteriorating the pump components.

Fix: To identify a failing fuel pump, first, inspect your vacuum fuel pump for cracks. If you see fuel outside of the fuel pump or cracks in the pump, the pump will no longer be able to create the pressure needed to pump fuel. 

Using the fuel shut-off valve, if your mower has a valve, or clamps to stop and start fuel flow will help you control fuel flow. Stop and start flow to make sure you are getting fuel to the pump.

Once you verify your pump is getting fuel, check to make sure that fuel is being pumped out of the pump in a steady or pulsating flow to identify whether or not your fuel pump is bad.

Plugged Fuel Filter

Your fuel filter is a line of defense to prevent dirt and debris into the engine by straining the fuel. Make sure the fuel that is running into the filter is also running out of the filter.

If it does not, you must replace it because it is most likely clogged. 

Fix: Replace the fuel filter if you have found your fuel flow stops at the fuel filter. Install a new fuel filter on your Simplicity if needed. You will find an arrow on the fuel filter housing that must be installed with the arrow pointed in the direction of your fuel flow.

Clogged Fuel Line

Old fuel and dirt leave deposits that can clog your Simplicity mower’s fuel line.  

Fix: Remove the fuel line, spray carb cleaner into the tube, and use compressed air to blow air through the tube until the line is free of dirt and gummy residue. You can also replace it with a new fuel line

Clogged & Dirty Carburetor

The function of the carburetor is to regulate the right amount of gas with the right amount of air so your engine can create combustion. Carburetors can get crusty buildup and gummy deposits from using old fuel containing ethanol.

When the carburetor is no longer to regulate the fuel your engine receives, your Simplicity’s engine will run rough or it may not even start at all.

Fix: If you are somewhat mechanical, you can try to clean the carburetor yourself, otherwise, bring it to your lawn mower repair shop. You can find steps for cleaning your carburetor in this article

You may choose to replace the carburetor if it appears to be in very bad condition. 

Bad Battery, Loose Cables, or Corroded Terminals

Your Simplicity lawn mower requires a charged battery in order to start. If your cables happen to be loose or your battery terminals show signs of corrosion, they can cause your mower starting problems.

Fix: Test your battery with a multimeter. You need a reading of about 12.7 volts. Charge your battery if it is lower than this level.

You can find more information on charging your battery here. If your battery does not hold a charge, you will need to replace it with a new battery. 

Bad Safety Switch

Your lawn mower may use several safety switches in its operator’s presence control system. The switches are designed to kill the engine when the operator leaves the seat.

A faulty switch may not recognize when the operator is in or out of the seat causing your mower not to start. 

Fix: You can temporarily bypass the safety switch to identify a bad switch. Do not operate a mower without the safety switch installed for your safety. Always have safety switches installed and working on your equipment. Replace a bad switch. 

Bad Ignition Switch

You insert the key into your ignition switch and turn it only to find nothing happens. Your Simplicity mower does not start. The ignition switch can be the culprit. You can use a multimeter to test the ignition switch 

Fix: Replace the switch if bad 

Faulty Ignition Coil

The ignition coil provides voltage to the spark plug so it can fire and start the engine. The engine will not start if the spark plug isn’t able to fire.  

Fix: After you verified your spark plug is in good condition, check the continuity of your ignition coil using an ohm meter. Replace the ignition coil if you find a break in the continuity. 

Bad Starter Solenoid

A lawn mower solenoid is an electromagnetic switch that is like an on-off switch that actuates the starter motor to turn over the engine. A click or hum when turning your ignition key is an indication to check your solenoid.

Another indication your Simplicity mower solenoid may be bad is when a wire attached to your solenoid gets hot and begins to smoke or melt.

FIX: Test your Simplicity mower solenoid by following the steps here. Replace your solenoid if it is found to be bad.

Faulty Charging System

While the charging system isn’t the main reason your Simplicity mower won’t start, it can contribute to a weak battery that prevents the mower from starting.

When the charging system fails to charge the battery, the battery may not be able to start the mower the next time you go to use it.

A bad stator or alternator can be the problem along with several other electrical parts. Read this article to test your charging system here using an ohmmeter. 

Fix: If you believe the problem to be in your charging system, I suggest you allow a small engine mechanic to identify which part of the charging system is your problem. Taking a guess at the problem and throwing parts at your mower can get pretty expensive.

Incorrect Starting Procedure

A Simplicity mower has safety features that won’t allow your mower to start unless you follow their starting procedures which include setting your parking brake.

Make sure the choke setting is correct. The choke restricts airflow allowing more fuel into the cylinder to start a cold engine. You must adjust the choke so it doesn’t continue to restrict airflow once the engine is warm or it will shut down.

Fix: Refer to your Simplicity operating manual to ensure you are operating your lawn mower correctly so you don’t set off the safety features that won’t allow it to start.