Cub Cadet Mower Spins But Doesn’t Start (FIXED)

Turning the key, pressing the button, or pulling the starter cord on your lawn mower has no effect. The engine cranks over, but you can’t get it to fire up.

Turning over but failing to start is typical of a Cub Cadet mower when there is insufficient fuel, air, or ignition source.

A dirty spark plug, the wrong choke setting, a jammed choke, a clogged air filter, a clogged fuel line, a clogged fuel filter, a filthy carburetor, a faulty fuel pump, or old gas might all cause the Cub Cadet mower to turn over but not start.

Do not attempt any fixes until the wire from the spark plug has been removed. Follow all of the additional safety procedures outlined in the Cub Cadet owner’s manual.


Be sure to read and understand the operator’s manual before attempting any diagnosis, repairs, or use of the equipment. Consult a professional if you lack the experience, training, or health to make the repair safely on your own.

Cub Cadet Lawn Mower Won’t Start for These 9 Common Reasons

Cub Cadet Lawnmower Has a Stuck Choke or Is Set to the Wrong Position

When the engine is cold, the choke is used to restrict airflow and make it easier to start. This is done so that a cold engine receives more fuel than it needs to start up.

After the engine has warmed up, the choke lever needs to be pushed to the open position to allow for more airflow and to keep the engine going. To begin cranking a warm engine, the choke must be released.

If the choke lever is in the wrong place, your Cub Cadet may be difficult to start or impossible to start at all. The choke should be closed when the engine is cold and open when it is warm.

If the choke is adjusted correctly but airflow issues persist, verify that the plate is not stuck and the cable can be moved easily. Carburetor cleaning can be used to help free a jammed choke plate and linkages.

If the cable appears to be stretched or worn, it should be replaced with a new Cub Cadet choke cable.

A Cub Cadet Lawnmower with a Clogged Air Filter

After turning over, a restriction in airflow is another possible cause of your Cub Cadet’s inability to start. The air filter serves a key purpose in protecting the engine from premature wear caused by dirt entering the air intake system.

If the filter isn’t regularly cleaned or replaced, it might become clogged with dust and other particles. Because of this, the engine and filter may not get enough air.

At the start of each mowing season, I recommend getting a new air filter and cleaning it multiple times throughout the season. Before starting up your Cub Cadet, check to see that the air filter is in good working order.

If your engine has a pre-cleaner, you can cleanse the foam pre-cleaner and paper air filter by following the instructions provided below.

If you own a Cub Cadet mower and aren’t sure what kind of filter it has or how to clean it, see your owner’s manual.

If you want to find out more about air filters, look into Lawn Mower Air Filter Guide: Types, Variations, and Maintenance.

Cleanse a Cub Cadet Mower Paper Air Filter

  • Remove the filter from the air filter housing. Keep the air filter clean and free of debris.
  • Use a clean, dry rag to wipe out the air filter housing and remove any remaining dirt or debris.
  • Tap the paper air filter against a hard surface to remove as much dust as possible.
  • Hold the paper filter up to a light to see if any light is passing through it.
  • When there is available light, recycle your filters.
  • Replace the filter if it has been broken, is very dusty, or is not allowing any light through.
    After installation, replace the air filter’s cover (If your push mower has a foam pre-filter, follow these instructions to clean it and then install it before you secure the filter cover)

Mowers with foam pre-filters should have their foam components regularly cleaned. To begin, several pre-filters may be used by various engines.

In order to further limit the input of dust and particles, conventional paper air filters are typically employed in conjunction with foam pre-filters. The paper pre-filter will be ruined if oil is introduced.

  • Check the pre-filter. Substitute it if you find any tears or if it has gotten brittle from lack of use.
  • Water and gentle dish soap can be used to clean the foam filter of oil and grime.
  • To remove any traces of soap from the water, give it a good rinse.
  • Flatten out and dry in the air. Leaving the filter in the sun will speed up the drying process.
  • After the foam pre-filter and paper primary filter have dried, reinstall the cover.

Spark Plug on a Cub Cadet Lawnmower Covered with Grime

You can examine the spark plug(s) later if you take them out. A 3/4″ or 5/8″ socket wrench, as appropriate for your engine model, is needed. Check the spark plug and see whether it’s working properly.

When a spark plug is broken or covered in grime, it might produce a weak or nonexistent spark. Without spark, the engine won’t fire up and keep going.

Faulty spark plugs can be identified by their darkened tip, scorched electrode, or cracked porcelain. If you notice any of these issues, you should replace the spark plug.

The solution is to see if a clean and functional plug can be cleaned. A little wire brush will do the trick for getting rid of the carbon buildup.

After double-checking the electrode gap, you can put the spark plug back in. The connection to the spark plug is then secured.

A healthy spark plug is essential for a lawn mower to perform at its optimum, so I recommend replacing it at the beginning of each season.

A Cub Cadet Lawnmower Running on Old Gas

As you may or may not know, gas has a shelf life. As soon as the 30-day mark has passed after purchase, it will begin to malfunction.

Fuel limitation and component failure might result from varnish and sticky deposits left over from spent gas.

The correct fuel for your Cub Cadet lawn mower must be purchased frequently and used within 30 days. Stay away from gas that contains ethanol.

Only fuel with a minimum 87 octane rating and 10% ethanol content should be used. Mowers powered by 4-cycle engines like those used in Cub Cadet run on gasoline. The engines in 2-cycle Cub Cadet mowers use a combination of gas and oil for fuel.

Cub Cadet lawn mowers run on this fuel type; it is recommended for use with 2-cycle and 4-cycle engines, respectively.

The solution is to use a fuel siphon pump to remove the old gas from your Cub Cadet’s tank.

Fresh gasoline and a fuel stabilizer, such as Sea Foam, will assist clean the fuel system and reduce moisture. Learn more about sea foam’s benefits by reading this article.

If you’ve managed to start the mower, let it run for a while so that the gas and fuel additive can move through the engine. If you’re still having trouble starting it, continue on to learn about some more fuel-related problems you might check for.

Cub Cadet Lawnmower Fuel Filter Clogged

A gasoline filter serves to remove debris from the fuel supply. To filter the fuel as it exits the fuel tank, an inline fuel filter is installed between the fuel lines.

If the filter isn’t changed frequently enough, it can become clogged. The mower may turn over but fail to start if a sufficient amount of fuel cannot enter through the filter.

The problem can be fixed by installing a new gasoline filter in lieu of an old one.

Cub Cadet Lawnmower Fuel Line Clogged

The next step is to trace the gasoline line from the tank to the carburetor. Check any obstructions in the fuel line that could be causing the lawn mower to crank but fail to start.

If you don’t find any creases, examine the fuel line for a restriction. To begin, turn off the fuel supply by using the fuel shut-off valve or pinch-off pliers.

Remove the end of the line nearest to the fuel tank and place it in a container to test the flow after turning on the fuel supply.

If a lawnmower’s fuel line isn’t getting enough gas, remove the line and switch off the gas.

Carburetor cleaning should be sprayed into the line. The purpose of this is to remove the obstruction. Compressed air can then be blown through the line to clean out the obstruction. Maintain the use of compressed air and carburetor cleaning until the obstruction is removed.

Once the blockage has been removed, the gasoline line can be reconnected. If the obstruction cannot be removed, or if the fuel line is old and showing signs of cracking, a new one must be installed.

Lawnmower Fuel Pump Failure on a Cub Cadet

A gasoline pump is required on a Cub Cadet when the carburetor is mounted above the tank. The pump’s job is to overcome gravity by pumping fuel uphill to the carburetor.

Most mowers today run on fuel pumped using a suction system. This fuel pump connects to the crankcase vacuum to provide the carburetor with fuel.

If the gasoline pump develops cracks or stops working altogether, it must be replaced. If there are no visible cracks or fuel leaks, you can take simple steps to inspect the fuel pump’s condition.

Before you try to test the pump, be sure fuel is getting to the inlet port. (If you aren’t, perhaps there is anything blocking the gasoline line or the fuel filter.)

After verifying fuel flow to the pump, the solution is to disconnect the fuel line from the carburetor and store it in a suitable container. Turn on the gas and the mower to see if the pump is working.

The gasoline line should have a steady or pulsating flow of fuel. If not, then you should probably replace the gasoline pump.

If your Cub Cadet has an electronic fuel injection pump, you can check the pressure with a fuel pressure gauge. Fuel pressure requirements are detailed in your Cub Cadet’s manual.

If the fuel pressures are below the threshold set by the engine manufacturer, a fuel pump replacement is required.

A Cub Cadet Lawnmower with a Filthy Carburetor

The carburetor is the part of the engine that mixes fuel and air for combustion. If there’s a problem with the carburetor, you won’t be able to get your Cub Cadet to start.

Far too often, old gas is the primary reason a carburetor doesn’t work. Used fuel can leave a varnish that might choke the fuel jet or cause internal parts to stick.

If the carburetor fails to function, the problem can be fixed by either cleaning it, repairing the broken pieces, or purchasing a new one.

Before you start taking out the carburetor on your Cub Cadet, you need do the following:

  • Make sure the fuel is reaching the carburetor.
  • The air filter should be removed.
  • Spray some carburetor cleaner into the mower’s air inlet and then turn it on. If your vehicle starts up, uses the carburetor cleaner, and then runs slowly or cuts off once the cleaner is gone, the carburetor is likely unclean. Dismantle the carburetor and either cleanse it or substitute it without using any starting fluid.

Cub Cadet Gas Cap with Blocked Fuel Vent

Fuel tanks need to be vented so that the pressure inside the tank is equal to the outside air. A Cub Cadet lawnmower’s vent might be located in the fuel cap.

When the vent becomes blocked, no air can escape the fuel tank, creating a vacuum. This vacuum prevents gas from entering the carburetor. When there isn’t enough petrol in the tank, the lawnmower will turn over but won’t start.

Try starting the mower after loosening the gas cap to see if that resolves the problem. It could be that you forgot to replace the gas cap.

Keep the mower running while you tighten the cap to prove that it is the cap and not the mower. If it sputters, turns off, and won’t turn back on unless you remove the cap, the problem is internal.

The solution is to get a new gas cap to replace the old one.

You Still Can’t Get Your Cub Cadet Snowblower to Work?

Problems with your snowblower are inevitable after some time of ownership. Problems with the auger not moving, dying, or beginning are all possibilities.

I have compiled a list of potential triggers for these problems to help you locate them more quickly. Read “Common Cub Cadet Snowblower Problems and Solutions” to learn more.

If you encounter an issue that is beyond the scope of your repair expertise, don’t hesitate to get in touch with your neighborhood Cub Cadet dealer for assistance.