Mower Care

How to Start a Lawn Mower – Everything You Need to Know 

Gardeners at every skill level can encounter issues starting a lawn mower, with a variety of causes behind them. In this guide on how to start a lawn mower, we’ll explore the basic techniques to turn a lawn mower on, and look through some of the issues that could arise. Sims Garden Machinery sells a range of gardening equipment including lawn mowers, bringing over 100 years of experience to our work.

Before Starting Your Petrol Lawn Mower

Your mower will need both petrol and engine oil in order to start correctly. Your lawn mower will likely have a four-cylinder engine, but older models may have a two-cylinder model. For a two-cylinder engine, the petrol and oil must be mixed together and added. 

The precise mixture, alongside the recommended oil, will both be listed within the instruction manual. Four-cylinder engines will take both oil and petrol separately, with a dipstick indicating the line to fill the oil tank. If the petrol in your tank has been there for several months you may need to replace it with a fresh supply. You should also ensure that there are no obstructions within the blades of your mower, disconnecting the spark plug if there is anything that needs removal.

How to Start a Petrol lawn Mower

a man gripping lever on a lawn mower handle

Your petrol lawn mower will usually have a priming button, which will be red or black, that you will need to press 3 or 4 times before starting the engine. Check your manual if you can’t find the priming button, as some models do not have one. You’ll then need to pull the starter cord on your mower in quick movements. While starting the mower in one pull is possible, taking several attempts is normal. It’s also worth noting that if your lawnmower has a lever by its handle you’ll have to grip this simultaneously. If your lawn mower’s engine doesn’t make any noises when pulling the starter cord,  you should check that the spark plug is firmly attached.

How to Start a Lawn Mower With a Choke

A lawn mower choke is a throttle control, designed to allow adjustments to the level of air that a lawn mower can pull in. Chokes will either be automatic or manual, and if manual you should adjust the choke to restrict air, as this will help your lawn mower to start. Once the engine is running, you can adjust the choke to allow more air in. These options should be clearly marked on your lawn mower, or explained within its manual. As long as you follow the instructions, it shouldn’t make your mower any harder to start. Automatic chokes, such as those commonly found in riding mowers, will perform these tasks for you.

How to Start a Lawn Mower With a Bad Starter

It’s always worth having a few goes with the rope before giving up. While a one pull start is obviously preferable, even a reasonable lawn mower could easily take 5 attempts to start. You can also press the primer again 3 or 4 times before trying the starter again. If this doesn’t work there are a few things to try. There could be issues with the battery. Firstly, check if it is leaking, in which case you will likely need to replace the battery. 

Then, check that it is charged with a voltmeter. If it is low or empty, charge it with a charging cable. Next, you can check the starter solenoid, which takes current from the battery to the motor. It will be either round or square, with 3 or 4 posts coming out of it. If your mower won’t start but the solenoid makes a clicking sound or hum it could need to be replaced. 

The ignition switch is another potential reason why your lawn mower won’t start, due to damage or corrosion to the wire. These can normally be replaced. Finally, there could potentially be an issue with the starter motor. You can connect the starter motor to a battery with a jumper cable and a negative terminal screwdriver. If the motor won’t start and is making clicking sounds, it is faulty. In this case, you will need to have your starter motor replaced.

What to Do if Your Lawn Mower has Been Sitting For Some Time

If your lawn mower has been sitting for a long time your main concerns will be replacing the petrol left in the tank, and checking the level of oil in the tank. You should also check that the spark plug is attached. As long as the petrol is fresh and there is the correct level of oil, a lawn mower that has not been used for some time should start normally. 

How to Start a Lawn Mower in Cold Weather 

When using a lawn mower in cold weather or during the winter, it’s crucial that you use a motor oil that is specified for the current temperature range. Regular motor oil can struggle to start when cold, meaning you should opt for oils like a 5W-30, designed to work at lower temperatures. Your lawn mower instruction manual should indicate which oils can be used when it is started after winter.

Our Range of Lawn Mowers for Sale

Whether you’re looking for a quality petrol-powered mower or an electric mower, Sims Garden Machinery stocks a huge range of quality products, with delivery across the UK. We stock ride-on and walk-behind models, perfect for enthusiasts and professionals alike. When delivering our lawn mowers, a member of our team will assemble and demonstrate your new machine, ensuring many years of quality use. 

Browse our huge selections of lawn mowers today.

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