How To Start A Gas Lawn Mower? [Reasons Lawnmower Isn’t Starting]

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By Kirsi Jansa

Starting a gas lawn mower is an easy task. You just have to be mindful of a few things, and you will be up and running in 2-3 minutes.

Start a gas lawn mower

Steps Required to Start a Gas Lawn Mower

Prepare the Lawn Mower

Before attempting to start your gas lawn mower, ensure it is on a flat surface. Clear the area of any obstacles, debris, or tall grass that might interfere with the mower’s operation. Additionally, ensure the mower’s blades are disengaged, and the handle is in the correct position.

Check Gas and Oil

Before starting your mower, it’s essential to check the gas and oil levels. The process can differ depending on whether you have a 2-stroke or a 4-stroke engine.

2-Stroke Engines: These engines require a mixture of oil and gasoline. Refer to the owner’s manual for the correct oil-to-gas ratio, typically around 1:50 or 1:40. Mix the gas and oil thoroughly in a separate container before pouring it into the fuel tank.

4-Stroke Engines: 4-stroke engines have separate compartments for oil and gas. Ensure the oil level is within the recommended range by checking the dipstick, and fill the gas tank with fresh gasoline.

Check Spark Plug

The spark plug is crucial for igniting the fuel-air mixture in the engine. Ensure it is clean and correctly gapped according to the specifications in the owner’s manual. If the spark plug is dirty, clean it with a wire brush or replace it if it shows signs of wear.

Prime the Carburetor

Priming the carburetor is necessary to start the engine, especially if the mower has been idle for a while. Locate the primer bulb, usually situated near the carburetor. Press it several times (usually 3-5 times) to deliver a richer fuel mixture to the engine, aiding in the starting process.

Open the Throttle

Before starting the mower, set the throttle to the start or choke position. This position allows more fuel into the engine, making starting easier. Once the engine has warmed up, you can adjust the throttle to the desired running position.

Start the Engine

Gas lawn mowers can be started using either a recoil start or an electric start.

Recoil Start: This is the traditional method, where you pull a starter rope to turn the engine over and start it. Hold the safety bar or bail bar on the handle, pull the starter rope slowly until you feel resistance, then pull it briskly. Repeat if necessary until the engine starts.

Electric Start: Some modern mowers come with an electric start option. Ensure the battery is charged, hold the safety bar, and turn the key or push the start button to begin the engine. Release the key or button once the engine has started.

After starting the engine, let it run in the choke or start position for a few minutes, then adjust the throttle to the desired running speed. The mower is now ready for use. Always refer to the owner’s manual for any model-specific instructions or precautions.

Reasons your Gas Lawn Mower is not Starting [Troubleshooting Guide]

Empty or Stale Fuel

Old or stale fuel can cause starting problems as it may not combust properly. An empty fuel tank is a straightforward reason the mower won’t start.

How to Fix: Drain old or stale fuel and refill the tank with fresh gasoline. For optimal performance, use fuel stabilizers to maintain fuel quality during storage.

Fouled Spark Plug

A fouled or damaged spark plug can hinder the lawn mower’s starting by preventing the fuel-air mixture from igniting in the combustion chamber.

How to Fix: Clean the spark plug with a wire brush or replace it if it appears damaged or excessively worn. Ensure the new spark plug is gapped correctly.

Clogged Carburetor

Over time, the carburetor can become clogged due to residue and stale fuel, preventing the correct air-fuel mixture from reaching the engine.

How to Fix: Clean the carburetor thoroughly with carburetor cleaner or consider replacing it if cleaning does not resolve the issue.

Dead Battery (For Electric Start)

A dead or weak battery will prevent an electric start lawn mower from starting as it cannot turn the starter motor.

How to Fix: Charge or replace the battery. Ensure the new battery is of the correct specification and is properly connected.

Blocked Fuel Filter

A blocked fuel filter can restrict the flow of gasoline to the engine, preventing the lawn mower from starting.

How to Fix: Replace the fuel filter, as it is typically a low-cost component and can be challenging to clean thoroughly.

Faulty Ignition Coil

A faulty ignition coil will not produce the electric spark to ignite the fuel-air mixture in the combustion chamber.

How to Fix: Replace the ignition coil with a new one that matches the specifications of your lawn mower model.

Engine Flooding

Engine flooding occurs when too much fuel enters the combustion chamber, making it difficult for the engine to start.

How to Fix: Wait around 15 minutes to allow the excess fuel to evaporate before starting the mower again. Avoid over-priming in the future.

Reasons your Gas Lawn Mower is not Starting [Troubleshooting Guide]

Frequently Asked Questions

Which gas is best for lawn mowers?

For most lawn mowers, fresh, unleaded gasoline with a minimum octane rating of 87 is suitable. It is recommended to use ethanol-free gas where available, as ethanol can cause issues in small engines.

Which engine oil is best for lawn mowers?

For lawn mowers with four-stroke engines, SAE 30 is a common choice in warmer temperatures, while a 5W-30 or 10W-30 may be used in colder conditions. Refer to the owner’s manual for specific recommendations for your mower model.

Which is better: electric or gas lawn mower?

The choice between electric and gas lawn mowers depends on individual needs. Electric mowers are quieter, more environmentally friendly, and require less maintenance, while gas mowers are typically more powerful and better suited for larger lawns and tougher grass.

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