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Why Won’t Your Lawn Mower Start After Winter? 7 Possible Reasons

Lawn Mower

After your favorite lawn mower was left in storage for the entire winter, you decide to start the season of mowing again. You take your lawn mower out of the shed and plan your day, but realize your lawn mower is not starting after many attempts. In the article below, you’ll find a list of all the problems that may occur in your lawn mower after a long winter.

The good news is all these problems are easily fixable and inexpensive, so you will have a healthy running lawn mower in no time. Even though that is the case, it is not pleasant to have a lawn mower that won’t start properly, so if you want to avoid this in the future, make sure to read on for ways of storing your lawn mower adequately.

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The 7 Reasons Your Lawn Mower Won’t Start After Winter

1. Dead spark plug

Replacement of the spark plug of lawn mower_Alexsander Ovsyannikov_Shutterstock
Image By: Alexsander Ovsyannikov, Shutterstock

Every lawn mower has an electrical ignition system. This system generates a spark in the cylinder and the plug, which causes combustion. When you don’t use your lawn mower for some time, especially after a long winter, the spark plug may corrode. This can cause the lawn mower to refuse to start. If you suspect your spark plug is faulty, you may need to inspect it first. Use a socket wrench to check the spark plug and look food any signs of corrosion. You may find that your spark plug is not dead but covered in carbon and just needs a good clean.

  • Decreased fuel efficiency
  • The engine stops running suddenly
  • The lawn mower cannot start


You need to replace the spark plug if it is corroded, damaged, or has a dark color. Remove the damaged spark plug and install a new one. The installation of a new spark plug is easy and inexpensive but make sure to buy the correct spark plug for your lawn mower.

If the spark plug is covered in dust and debris, you can easily clean it with a spray-on cleaner and a wire brush. You can also use a knife to scrape off thick coats of build-up.

2. Worn out or dead battery

A very common reason a lawn mower won’t start after winter is a dead battery. When sitting unused for too long, the battery can lose its charge. As the batteries lose charge, your lawn mower is less likely to start. Another common reason is leaving the battery uncharged for the entire winter. Batteries that are not fully charged will tend to freeze at much lower temperatures. If you left your lawn mower with an uncharged battery before winter, the chances are high it is ruined and needs replacement.

  • Low voltage readings
  • The battery won’t charge fully
  • The battery doesn’t stay charged for long
  • The lawn mower cannot start


Try charging your batteries after winter. If you still experience any of the symptoms mentioned above, your battery will need replacement.

3. Stale gas

Puring gasoling in lawn mower_Gabo Tinz_Shutterstock
Image Credit: Gabor Tinz, Shutterstock

When your lawn mower sits intact for a long time, especially after winter, the gas can go bad or stale quickly. When the combustion in the lawn mower’s engine occurs, there is a process that occurs between the hydrocarbons in the gas and the oxygen. If the gas inside your lawn mower loses its combustibility due to exposure to heat or air, your lawn mower will most likely refuse to start.

  • An unpleasant, sour, or pungent odor
  • Muddy or dark gas
  • It’s been a long time since you last changed or filled your lawnmower with gas


Remove any leftover stale gas and replace it with new, fresh gas. If your fuel tank is empty, simply pour in fresh gas.

4. Clogged air filter

The air filter is responsible for preventing dirt, dust, and debris from entering the engine. When your lawn mower sits idle for a long time or after winter, dust and debris can accumulate in the air filter, not allowing for enough airflow through the engine, which can additionally prevent your lawn mower from starting. At one point, you may even find holes in the fibrous material of the air filter, which will allow dirt to enter your engine.

If dirt and debris find their way to the internal parts of your lawn mower, it can cause wear to the engine and other components much faster.

  • Spluttering engine
  • The lawn mower won’t start
  • More fuel consumption


To check whether your air filter is clogged, you must remove the housing first. Inspect for any signs of dust and debris. To remove debris stuck in the air filter, use a soft brush carefully.

5. Dirty Carburetor

Lawn Mower Carburetor_Yes058 Montree Nanta_Shutterstock
Image Credit: Yes058 Montree Nanta, Shutterstock

Similar to a car’s engine, every lawn mower has a small carburetor to help run the engine. The purpose of a carburetor in the lawn mower is to allow the proper amount of fuel and air to enter the engine and combust. When you store your lawn mower for the winter, a small amount of fuel is left in the carburetor fuel bowl. The old leftover fuel can leave sticky and gummy residue in your carburetor, creating clogs and preventing air and fuel from entering the engine cylinder.

  • The engine starts but stalls during mowing
  • Smoke comes out of the muffler
  • The lawn mower won’t start
  • More fuel consumption


If your carburetor is clogged or dirty, you must remove it and clean it with carburetor cleaner. You must clean the carburetor’s built-up deposits for your lawn mower to run correctly again.

6. Water in the gas tank

When storing your lawn mower for winter, one of the crucial things you must do is put the gas cap back on. Never leave the gas cap off your mower or the storage can. Water can quickly accumulate in your gas if your lawn mower sits unused for extended periods, such as winter. Condensation is likely to occur and create water build-up in your fuel tank. This is one of the reasons why your lawn mower won’t start after winter.

  • Spluttering engine
  • The lawn mower won’t start
  • The lawn mower starts but cannot run properly


The safest solution for this problem is to remove your fuel tank, clean it thoroughly and fill it with fresh gas. Make sure to use gas that doesn’t contain ethanol. Ethanol draws moisture out of the air and condenses it on the bottom of your fuel tank.

7. Defective ignition switch

Ignition Coil
Image Credit: MuhammadIbrar, Pixabay

An ignition switch is a fundamental part of your lawn mower. It ensures that electricity reaches all the parts of the lawn mower. If the ignition switch doesn’t work correctly after winter, your lawn mower won’t start. After your lawn mower was in storage for the entire winter, there may have been some water or mechanical damage. You will have to examine the wiring to ensure all the connections are secure.

  • The engine won’t start
  • The ignition key gets stuck
  • The engine may start but cranks and turns off quickly


When your lawn mower has a faulty ignition switch, solenoid, or bad wiring, you will need to fix that issue quickly. You will most likely need to replace the ignition switch or the ignition coil, or you may need to wire the terminals correctly.

tool divider How to Properly Store Your Lawn Mower Before Winter

1. Remove the battery

Before storing your lawn mower for the winter, it would be a good idea to remove the battery and keep it healthy for the next season. It is best to keep the battery in a cool, dry place. Disconnect the battery cable from the battery, remove the battery, and clean it with a cloth. You may also need to clean the battery terminal using a metal brush and a cleaner product.

2. Clean your lawn mower

It would be wise to clean your lawn mower from any dirt, debris, or clumps of grass before storage. Use an appropriate tool to remove debris stuck in the lawn mower’s blade. You can use a brush or a hose since removing grass or mud from your mower may be challenging.

3. Use a fuel stabilizer

Use a fuel stabilizer to keep the gas in your lawn mower from going stale. Putting a small amount of fuel stabilizer in the tank eliminates the need to drain the fuel and ensures a healthy lawn mower that is ready for the next season.

4. Store the lawn mower in a dry place

To keep your lawn mower as safe as possible from bad weather, consider keeping it in a garage or any other dry place. Choose a spot with excellent airflow to eliminate the risk of mold and corrosion developing on your lawn mower.

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Final Thoughts

Hopefully, this article will help you diagnose why your lawn mower refuses to start. There are many possible reasons why this may occur, and it is crucial to find a solution quickly to prevent further damage. Make sure to inform yourself how to keep your lawn mower properly stored before winter. Adequately storing before winter can keep potential problems to a minimum.

Featured Image Credit: Andres Siimon, Unsplash


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