Reasons a Cub Cadet Mower Won’t Start: The Complete List


It’s that time of week again when you need to cut your lawn, but this time, your Cub Cadet lawn mower will not start. Over my years of talking with homeowners and commercial customers at the lawn mower dealership, I have troubleshooted a lot of starting issues.  

There are many reasons why a Cub Cadet lawn mower won’t start including a loose spark plug connection, plugged air filter, bad fuel pump, bad battery, corrosion on the electrical components, dirty carburetor, bad switches or a faulty charging system. 

As frustrating as it is to have a mower that won’t start, I’m going to take you through a list of reasons why your Cub Cadet may not be starting. Hopefully the starting problem is a simple fix, and you can get back to mowing your lawn. Let’s find out! 

why your Cub Cadet won't start

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16 Reasons Why Your Cut Cadet Mower Won’t Start 

1. No Gas in Your Cub Cadet Fuel Tank 

You may be wondering why something as simple as gas in a fuel tank shows up on the list. Gas is an obvious reason why your Cub Cadet won’t start. As obvious as it seems, you may be surprised to learn of the number complaints I’ve received from customers about their starting problem when the culprit was no fuel in the lawn mower. 

Fix: Fill with fresh gasoline with an octane rating of 87-grade or higher. Choose a gas with an ethanol level no greater than 10%. Find more information on the correct fuel for your gas lawn mower hereOpens in a new tab.

2. Bad or Old Fuel 

Gas begins to deteriorate, break down and become less effective after about 30 days. The ethanol used in gasoline attracts moisture. This moisture, once it evaporates, leaves a gummy residue behind that can clog your fuel system including your fuel lines, filter, and carburetor. 

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 within 30 days, you need to add a fuel additive to stabilize the fuelOpens in a new tab.

Fix: Remove the old fuel, flush the tank and add fresh fuel. 

3. Faulty Cub Cadet Fuel Cap 

Your fuel cap has a vent. When this vent gets plugged, your fuel tank will create a vacuum preventing your Cub Cadet mower from drawing gas out of the fuel tank. 

Fix: Replace with a new fuel cap. You can find one on AmazonOpens in a new tab. or visit your local Cub Cadet dealership. 

4. Cub Cadet Has a Bad Spark Plug or Loose Connection 

Another reason your Cub Cadet won’t run may be due to a bad spark plug connection or a damaged spark plug. A plug that has carbon buildup or oil on the tip can foul out causing your engine to misfire. 

Fix: Remove your spark plug and inspect it for signs of carbon buildup or cracked porcelain insulator. Replace with a new spark plug(s). Make sure to gap them according to manufacturer specification. 

5. Cub Cadet Air Filter is Plugged

The engine in your Cub Cadet requires air to run. If your air filter gets extremely dirty, it can starve the engine of air because the filter cut off access to clean air. When the air flow is blocked by your air filter the engine must find air to continue to run. It will begin to overheat and may draw what air it can find from the crankcase which can cause extensive damage to the engine.

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 hereOpens in a new tab.

6. Bad Cub Cadet Fuel Pump 

The fuel pump exists to pump fuel to the carburetor. When the fuel tank sits below the carburetor a pump is need 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 pump, the pump will no longer being 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.

7. Plugged Cub Cadet 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 plugged. 

Fix: You can verify a good fuel filter by using the same steps above to verify you are getting fuel to the fuel pump. Turn off the fuel valve or use a clamp to stop the flow of fuel on the end of the tube coming out of the fuel filter. Place this line in a container, turn on the fuel valve or remove to clamp to verify you have fuel flowing into the container.

If you are not getting fuel to the fuel filter, you can check to make sure you have fuel flow to the filter. Replace the fuel filter if you have found your fuel flow stops at the fuel filter. Install a new fuel filter on your Cub Cadet if needed.

8. Cub Cadet Has a Blocked Fuel Line

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

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

9. Clogged & Dirty Cub Cadet 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 a 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 Cub Cadet 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. 

10. Bad Battery or Loose Terminals on Your Cub Cadet

Your Cub Cadet 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 staring problems.

Fix: Test your battery with a multimeterOpens in a new tab.. You will want a reading at about 12.7 volts. Charge your battery is if 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. 

11. Bad Safety Switch on Your Cub Cadet

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. Many people get injured by mowers annually by rolling them or falling off the mowerOpens in a new tab..  Always have safety switches installed and working on your equipment. Replace a bad switch. 

12. Bad Cub Cadet Ignition Switch 

You insert the key into your ignition switch and turn it only to find nothing happens. Your Cub Cadet 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 

13. Cub Cadet Ignition Coil is Bad

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. 

14. Bad Starter Solenoid on Your Cub Cadet

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

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

15. Cub Cadet Mower’s Charging System is Faulty

The charging system can drain the battery and not keep it charged causing your Cub Cadet to not start. A bad stator or alternator can be the problem along with several other electrical parts. Read this article to test your charging system hereOpens in a new tab. using an ohm meter. 

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.

16. Incorrect Operating Procedure to Start Your Cub Cadet Mower

Cub Cadet has safety features that won’t allow your mower to start unless you follow their starting procedures.

Fix: Refer to your Cub Cadet operating 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 or don’t allow it to start.

My top items to keep on hand to service & troubleshoot your lawn mower

Socket & Allen Wrench SetOpens in a new tab. – Tool set needed to service & troubleshoot your mower problemsCarburetor CleanerOpens in a new tab. – Clean clogs & buildup in fuel system
MultimeterOpens in a new tab. – To check voltage, continuity & current to identify electrical problemsFuel StabilizerOpens in a new tab. – Stabilize & clean your fuel to minimize fuel system buildup
12-Volt Battery ChargerOpens in a new tab. – Battery/trickle charger to start your mower & slowly charge your batteryFilter WrenchOpens in a new tab. – Helps loosen your filter
Oil Drain PanOpens in a new tab. – To collect oil with spout to place in containers for disposalBattery Powered InflatorOpens in a new tab. – Keep your lawn mower tires inflated to prevent uneven cutting or steering issues

Powered Equipment Team

We're just a guy and a girl obsessed with outdoor power equipment! We are excited to share the knowledge and tips we have learned over our combined 55 years in the power equipment industry. We have both ran equipment dealerships and took pleasure in helping our customers everyday providing equipment repair, parts, purchasing, and business tips to our residential and commercial clients. We hope our blog will help you with your next purchase, repair, or project.

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