Why Is My Lawnmower Not Starting? Reasons and fixes.


You take out your mower from the garage, where it has been sitting during the winter. You want to start mowing your grass, but the Lawnmower is not starting. You check if all looks ok, but you cannot detect and solve the problem. Luckily, you can check a few things, which will make your Lawnmower start again in most cases.

This article provides a detailed list of the most probable reasons why your Lawnmower is not starting and what solutions can be applied to make it start again.

Why is my Lawnmower not starting:

  1. Low level of gas in the fuel tank.
  2. A gummed up substance formed due to old fuel.
  3. Blocked fuel filter due to dirt and dust.
  4. Dead Battery issues.
  5. Spark arrestors may be clogged due to soot.
  6. Debris and old grass cause clogged air filters.
  7. A restricted Carburetor causes hindrance in starting.

What to do if your Lawnmower is not starting

The problems in starting the Lawnmower are directly linked with the engine’s problems and its various components. Below is the list of all possible issues that can hinder lawnmower ignition and their respective solutions.

● 1. Out of Gas:

Let us start our discussion with the most fundamental problems that can hinder the ignition of a lawnmower. The mower may be running low on gas, as an individual might have forgotten to refill its fuel tank the last time it was used.

– Solution:

This problem can be easily fixed by checking the fuel gauge. If it is low, then refill the fuel tank with gas and try igniting the mower. 

● 2. Stale gas:

This scenario exists when the Lawnmower has not been used for quite some time. In case the unit is being used after a winter season, the gas present in the fuel tank of the Lawnmower for a long time may have become stale since gasoline has a shelf life of only a month. If this limit is exceeded, the ethanol present in the gas might rust or clog the carburetor, causing the Lawnmower’s engine not to start.

– Solution:

This problem can be avoided by ensuring two measures.

  • Empty fuel tank: Empty the fuel tank after use before parking it for an extended period.
  • Fresh gas: Empty and refill the fuel tank with fresh gas before using the Lawnmower after a long time

● 3. Clogged fuel Filter:

The fuel filter’s primary goal is to filter off dirt or small particles present in the fuel from entering the carburetor; however, it is possible that the excess blockage of such dirt and small particles or stale gas can clog the fuel filter. This clogging can result in the fuel not reaching the carburetor, and thus the Lawnmower does not start.

– Solution:

This issue can be solved by

  • Use clean fuel: Using clean and fractional distilled fuel
  • Clean the fuel filter: Cleaning the fuel filter regularly
  • New filter: They are replacing the excessively clogged filter with a new filter.

● 4. Dead Battery:

Lawnmowers having switch ignition rather than manual string ignition can have battery issues that might hinder the unit’s smooth starting. The possible issues in battery can be the low-level of battery fluid or battery being dead due to its lack of action for a long time.

– Solution:

Following actions offer a solution to your battery problems

  • Battery fluid: Refill the battery’s recommended fluid from a mechanic shop nearby
  • Charge: Please charge the battery in case it is not providing the expected voltage or output
  • Replace: If the previous two solutions fail, try replacing the battery with a new one.

● 5. Spark plug issues:

Similar to other fuel driven machines, spark plugs are an essential component for starting a lawnmower. It provides the initial spark required to burn the fuel in the combustion chamber of the engine. However, if the spark plug is disconnected or is clogged with dirt, in that case, the engine is not provided with a spark, and thus it does not start properly.

– Solution:

To fix various issues related to spark plugs, the following initiatives are recommended.

  • Cleaning agent: In case if the spark plug’s metal threading is dirty, use a thinner or a metal cleaning agent along-with a brush to ward off the dirt from the metal threads of the plug, dry it with air and place it back on.
  • Reassemble or Replace: Disconnect the spark plug and insert it properly to relay the engine’s combustion chamber’s spark. Examine if the spark plug is not producing a spark, and then replace it with a new unit.

● 6. Clogged air filter:

Air filters are an essential component of lawnmowers. The Lawnmower’s engine incorporates combustion reactions to break the fuel and use it for performing various tasks; however, these combustion reactions require a significant air supply to carry out their process. If the air filter is dirty or clogged, it limits the air supply to the combustion chamber of the engine, and therefore, the engine starts missing while functioning or may not even start.

– Solution:

A clogged air filter can be fixed by

  • Paper filter: In a paper air filter, maximum dirt and dust can be warded off by tapping it by hand.
  • Foam filter: A Foam filter can be cleaned by washing through water and some cleaning agent along-with a brush.
  • Untreatable filter: In case if the filter is untreatable, replace it with a new unit.

● 7. Carburetor issues:

Most lawnmower experience issues in ignition due to problems present in their engine’s carburetor. The majority of these carburetor issues arise due to dirt and other additional fuel wastes present in the carburetor. This results in the reduction of engine efficiency, along-with problems in igniting the Lawnmower.

– Solution:

  • Disassemble the carburetor: Disassemble the parts of carburetors. Please place them in a container with a carburetor cleaner for an hour. Rinse the parts with cold water and reassemble them after properly drying them.
  • Mechanic: If cleaning does not solve the ignition issue, then visit a mechanic.

– Additional Preventative Measures:

While performing these self-troubleshoot initiatives, keep the following precautions into consideration.

  • Highly flammable: The fuel tank of the mower is highly flammable. Therefore, while applying the fixes discussed above, there should be no fire, cigarette, or any material, which can ignite the fuel tank near the Lawnmower.
  • Remove the sparkplug: Take off the spark plug before performing any cleaning action on the mower. Likewise, use gloves and safety measures while dealing with the deck of the mower.

Frequently Asked Questions:

● 1. How can I detect the spark of a spark plug?

You can easily detect the spark of a plug by following these simple steps

  • Step 1: Unplug the spark plug and remove the plastic covering of the plug.
  • Step 2: Attach the lead onto the plug and touch the plug is threading against the engine’s metal.
  • Step 3: Pull the ignition cord, and the spark is produced, which is easily detectable by the naked eyes

● 2. Can a rusty carburetor be detected? If yes, then is there any solution available to treat a rusty carburetor?

Yes, the rusty and corrosive carburetor can be detected by opening the carburetor and examining the inside of the carburetor. If there exists a white powdery situation on the inside, it means the carburetor has been rusted.

 In terms of fixing a rusted and corrosive carburetor, usually, there is no legit solution that addressed this situation. However, one can try boiling the rusty carburetor in vinegar for 30 minutes. This process is effective in warding off the rust of the carburetor’s surface and is economically cheap as well since vinegar is cheap and one has nothing else to lose except time. 

● 3. My mower lost power during a mowing session. What could be the possible reason behind it?

Given the present scenario, the following reason can compel the mower to lose power while mowing. These reasons might be,

  1. Fuel level: Low engine fuel level
  2. Restricted deck: Clogging of dirt or debris on the deck of the mower
  3. Dirty carburetor: Presence of dirt in the carburetor or on the spark plug of the mower.
  4. Loose blades: Loose or blended mower blades
  5. Dead battery: Discharged and dysfunctional battery.

● 4. Why my Lawnmower’s engine smokes? Can it be fixed? If yes, then how?

The lawnmowers might exhaust some smoke when the engine oil level is considerably high in the engine. Similarly, the smoke might be resulting from the presence of oil in the exhaust muffler. If the smoke is colored, then consult a mechanic rather than applying home fixes.

Final Remarks

Lawnmower, like other machines, might also experience some technical and mechanical issues. However, most of these issues are not complicated and can be addressed at home by an individual without spending a significant budget on his Lawnmower by taking it to a mechanic. However, similar to other machines, several precautions should be taken into consideration to ensure personal safety during the troubleshooting process.

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