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What Is An Auto Choke On A Lawn Mower? Find Out Here!

Written by William
Last Updated on March 28, 2021

What Does The Auto Choke Function Do On a Lawnmower?

If your lawnmower comes with an automatic choke function, you may be wondering what this choke does in your engine and how it differs from a manual one.

The automatic choke in a lawnmower is important to regulate the fuel to air ratio on your mower when you start it up, this choke automatically turns on your lawnmower when you are using it from a cold start. 

So as we can understand more about the auto choke on your mower and how it works, as well as how to adjust it, we have put together a short guide below that will give you all the essential info.

What Is An Auto Choke?

Let's start with what an auto choke is. We briefly explained above, the automatic choke is the part of the mower which allows your mower to turn on from a cold start or when the engine hasn't been used in a while. This choke is used on all vehicles with an engine that has a carburettor.

So in simple terms, the auto choke on your mower aids your mower in starting no matter how cold it is or how long its been since you turned the engine on.

How Does An Auto Choke Work On a Mower?

The auto choke is automatically activated when you switch the ignition of your mower on, from a cold start, the carburettor on your lawnmower will need more fuel than air to start-up, meaning that this choke will close slightly to block some of the air from entering the engine.

When the engine of your lawnmower becomes warm and reaches its ideal temperature, the choke will open up to allow a normal ratio of fuel to air.

What Is The Difference Between An Auto & Manual Choke?

On older lawnmowers, you may still find that they have a manual choke function, which would require the operator of the mower to pull the knob of the machine to activate the choke then push it back in when the engine on the mower has started and is running smoothly.

An automatic choke will do all this work for you and operates by using power from the mower's battery. You can easily see whether or not your lawnmower has a manual or automatic choke by looking to detect if there is a choke indication by the throttle of the mower.

Is It Bad To Leave The Choke Functioning On a Mower?

Because technology is great, automatic chokes allow us to forget about whether or not we turned the choke on or off on our mower.

But you might be wondering, what would happen if the choke was left operating on a mower while it's in use?

Well, number one it would probably ruin your spark plugs over time and you would waste a lot more fuel, due to the fuel to air ratio being richer in your engine.

Too much fuel in your mower's engine would eventually cause it to stall at some point too and may require you to drain the excess fuel from the engine of the mower which is a long yielded process. This is why auto-choke was invented, so as you wouldn't have to worry about forgetting to turn the choke off and to make starting your mower less hassle.

Why Is My Auto Choke Stuck On My Lawnmower?

Most auto chokes work smoothly on newer lawnmowers with no issues, but some common problems can occur such as your choke becoming stuck or the lawnmower only starting when the choke is set on.

Now, if the automatic choke on your lawnmower has become stuck, it may need some lubrication as rust is likely to build up around the choke area on the engine, your auto choke may have potentially failed too, which means you would need to replace it with a new choke.

If your lawnmower is only starting when the auto choke of your mower is on, that means you could have an issue with the carburettor of your lawnmower such as a blockage, meaning you would need to get the carburettor looked at by a professional or clean the engine yourself.

So as you can keep your auto choke running efficiently, we have listed out a couple of tips below about maintaining it.

  • Keep it lubricated - You should be oiling the spring of your choke to avoid rust building up and the mechanism becoming stuck over time.
  • Remove dirt with compressed air - Take off any dirt or debris that may seem stuck around your mowers choke with some compressed air to avoid any blockages or rust.
  • Check it once a year - Every year it's a good idea to inspect the choke on your mower, always make sure the mower is cooled down before doing this.

Why Is My Lawnmower Not Starting In Cold Weather?

As we already know, the automatic and manual choke help your mower start in cold weather, but what happens if your choke is working fine, but the lawnmower still cannot start?

We have listed briefly a few other causes which would be worth troubleshooting if your mower is not starting in cold weather.

  • You have out of date fuel - Old fuel is known for building deposits and causing issues with mowers, you should drain and replace this fuel or put a stabiliser next time to avoid it going bad.
  • The spark plugs are faulty - Dirty, old or loose spark plugs are one of the next most common issues as to why your mower is not starting in the cold, just simply change the plug to determine if this is the issue.
  • There is a clogged air filter - If your air filter is very dirty, this may also be a reason for your mower's engine to have issues starting rather than the choke.
  • The oil is not suitable for cold weather - A single grade oil may not be suitable for winter and only work in summer, oils tend to change thickness according to temperature, so you may need to look into a multi-grade oil that will be efficient in cold weather as well as warm.

Frequently Asked Questions About An Auto Choke On a Lawnmower

Is an auto choke or manual choke better on a mower? 

This depends on how well you know mowers and engines, an auto choke takes out the hassle of having to manually start the choke and stops you from worrying about remembering to turn it off, however, an auto choke is likely to have more issues than a manual one and can't be adjusted or fixed as easily as a manual if something goes wrong.

How long should I wait for my mower to warm up? 

You don't need to wait for your mower to warm up as it should be ready to use pretty much straight away after you turn the ignition.

What do I do if my engine is flooded from a faulty choke? 

If too much fuel has been let into your mower's carburettor you can try draining it and letting the air filter dry, if the engine still isn't working after this then you will need to take it to a professional to get fixed.

Final Words

To conclude, mowers with auto chokes allow you to start up the mower with no manual interference and permit your engine to get the fuel it needs before it warms up, helping it start smoothly no matter the weather conditions.

Depending on the mower that you buy, the machine will likely come with either a manual choke or an auto choke, for manual models you will need to push a valve multiple times to allow the mower to start properly.

About the author
Written by William
I have always had a passion for gardening and that with a background in selling lawn mowers for the past 10 years, I have become very knowledgeable in all types of gardening tools. The site TheBestMowers.co.uk was created as a hub where I can review and write about all of the tips around gardening.
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