Your Cub Cadet Lawn Mower Won’t Stay Running: SOLVED!

As a homeowner, you take pride in your home’s appearance. Keeping up with your lawn care tasks is important to keep your home’s exterior looking its best. When your Cub Cadet stops running, you need to get it repaired quickly because it doesn’t take long for your lawn to appear overgrown.

A Cub Cadet lawn mower won’t stay running when old or dirty gas causes fuel restrictions in the fuel filter, fuel lines, fuel pump, and carburetor. A plugged air filter, bad spark plug, or faulty ignition coil can also result in a Cub Cadet that won’t continue to run.

Keep reading for more items. Many of these items can be easily repaired by most homeowners, but you may run into items you don’t feel experienced enough to work with without causing injury to yourself or damage to the mower.

If this is the case, consult your local Cub Cadet dealership or local lawn mower repair shop for assistance.

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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 a Cub Cadet Lawn Mower Won’t Stay Running

Bad or Old Gas

Gas that has been sitting around, in your lawn mower or in a storage container, will begin to break down as quickly as 30 days after purchasing it.

Ethanol-based gasoline attracts moisture from the air causing corrosion in the fuel system and leaving behind gummy deposits that restrict fuel flow to the engine. This can cause running and starting issues.

This water and ethanol mixture will separate from the gasoline over time sinking to the bottom of the tank. This mixture runs hotter through the engine which can result in damage.

Read more about ethanol and the right gas to use in “This is the Type of Gas Cub Cadet Lawn Mowers Use“.

Fuel Restriction

As I already mentioned, old fuel can cause clogging issues in the fuel components. Without sufficient fuel flow, a Cub Cadet mower won’t stay running. Old fuel, dirt, and debris can cause restrictions resulting in:

• Plugged fuel filter
• Clogged fuel lines
• Bad fuel pump

For more information on fuel restrictions and how to fix them, check out “This is Why Your Cub Cadet Isn’t Getting Fuel“.

Dirty Carburetor on a Cub Cadet Lawn Mower

The purpose of a carburetor is to regulate the amount of fuel that gets mixed with air so the right proportion of gas and air enter the cylinder to create combustion. The carburetor is known to get dirty from old fuel and stop functioning correctly.

The fuel jet may become clogged or the small components on the carburetor may be unable to move freely. This will cause an insufficient amount of fuel to get to the engine causing a running problem.

To better determine if you are experiencing a running problem due to a dirty carburetor, perform these quick steps:

• Confirm you are getting fuel to the carburetor. Do this by ensuring the fuel pump is moving fuel to the carburetor. If it isn’t, check the fuel filter, fuel lines, and fuel pump using the steps found here.
• Next, remove the air filter from the air filter housing being careful not to allow any dirt to fall into the air intake.
• Spray carburetor cleaner into the air intake and allow your lawn mower to run. If it runs strong but then begins to run sluggish and possibly shut off, chances are your carburetor is dirty.
• Proceed with disassembling the carburetor and cleaning it.

To clean your carburetor follow these instructions for cleaning your Cub Cadet carburetor here. If you continue to have problems with the carburetor, you may have to rebuild it or replace it with a new carburetor.

Plugged Air Filter

An air filter is used so the engine gets clean air that is free of the dirt and debris that gets tossed into the air while mowing. The air filter needs to be cleaned or replaced regularly to avoid a plugged air filter.

When a filter collects so much dirt that sufficient air cannot pass through the filter, it will starve the engine from getting air causing it to run sluggishly and possibly stop running.

Not only will running a dirty air filter cause running problems, but it can also cause significant engine damage.

Keeping the filter clean and replacing it with a new one when needed is a small investment in time and money towards keeping your mower running at its best.

Replace the air filter annually and clean it several times throughout the mowing season using these steps:

Clean a Cub Cadet lawn mower paper air filter:

• Remove the air filter from the housing.
• Wipe out any dirt remaining in the housing. Be careful to not let any dirt fall into the air intake.
• Tap your filter against a solid surface. What you are trying to do is knock as much dirt out of the filter that will come loose and fall out.
• Hold your air filter up to a light source and make sure you can still see light shine through the paper element. If you can, go ahead and reuse your air filter.  If you can’t, it’s time to buy a new one.
• Reinstall the air filter and attach your air filter housing cover.

Clean a Cub Cadet lawn mower foam air filter:

• Remove the air filter from the housing.
• Wipe out any dirt that is in the filter housing. Don’t allow any dirt to fall into the air intake.
• Inspect your filter. If you find any dark spots, or tears or your filter is dry and brittle, you must replace your filter with a new one. If it appears to be in good condition proceed with cleaning it.
• Wash your foam filter with water and mild detergent. Rinse to remove the soap from the filter.
• Lay flat to dry. Placing your filter in the sun will help speed up the drying process.
• Once the filter is completely dry, coat it with foam air filter oil. You want it completely covered with oil, but you don’t want it to be dripping with oil. If you get too much oil on the filter, ring out the extra oil or use a paper towel to absorb the excess oil.
• Reinstall the air filter and attach your air filter housing cover.

Choke Set in the Wrong Position

The choke is required to assist with starting a cold engine. The choke must be placed in the closed position so it restricts airflow and allows more gas into the cylinder to start.

Once the engine warms, the choke needs to be adjusted to the open position allowing more air to flow so the engine gets the correct gas-to-air mixture to continue to run.

If the choke isn’t adjusted correctly, the engine will begin to run sluggishly and won’t stay running because the amount of airflow is too low.

Dirty Spark Plug

A fouled spark plug can prevent a Cub Cadet mower from running. When it becomes dirty and coated with carbon, dirt, and oil, the plug will fail to spark. Remove the spark plug and check its condition.

If it is very dark in color, or has broken porcelain or burnt electrode, the spark plug must be replaced with a new one.

If the tip is lightly dirty and in good condition, you can proceed with using it, but you need to clean it with a wire brush to remove any carbon and dirt buildup.

Check the gap of the spark plug to make sure it is gapped to the manufacturer’s specification. You can find this information in your owner’s manual.

A spark plug that isn’t gapped correctly or one where the spark plug isn’t securely attached can also result in running problems with your Cub Cadet.

Once you confirm you are using a good spark plug or you replaced it with a new one, proceed with checking your ignition coil if you are still experiencing issues.

Bad Ignition Coil

The ignition coil can cause your Cub Cadet lawn mower won’t stay running. The windings on the ignition coil can separate and short out when the lawn mower gets hot.

This will result in the spark plug not being able to create spark because it is unable to get the voltage it needs. Check for a break in the continuity using an ohm meter.

Bad Fuel Cap

The gas cap on your Cub Cadet mower includes a vent to allow air to pass through the cap. This allows the air pressure to be equalized so the fuel tank doesn’t form a vacuum.

This vacuum will prevent gas from flowing out of the tank through the fuel lines. This will cause the mower to shut down because of a lack of gas to the engine.

Once the mower has stopped running, remove the fuel cap and start your mower. If it starts and runs fine, you may have a problem with the fuel cap vent.

For added confirmation, place the cap back on your fuel tank while allowing your mower to continue to run to see if the mower shuts off after running for a while.

Replace the Cub Cadet fuel cap with a new one.

Engine Overheats

When the engine in a Cub Cadet mower overheats, it will shut down and stop running. This could be due to a low engine oil level, the wrong type of oil, a clogged mower deck, and plugged air filter.

For additional reasons a Cub Cadet mower overheats, check out my guide 7 Things That Can Cause a Lawn Mower to Overheat.