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How Best To Clean A Clogged Lawn Mower Carburetor (without damaging it!)

Written by William
Last Updated on March 28, 2021

What's The Best Way To Clean a Lawnmowers Blocked Carburettor?

Carburettors on a lawnmower can easily become blocked or stuck with debris over time, causing start-up issues and many different engine problems, so in this article, we are going to tell you the best way to clean it.

The best way to clean a clogged lawnmowers carb is by removing it and identifying the issue, you can also clean it without removing it for better convenience too, the whole process should not take more than half an hour.

So as we can get into some deeper detail about what a carburettor is and how to clean it without damaging it, we have listed out some steps below to get you started and fix your blocked carb.

What Is a Carburettor On a Lawnmower?

Before we can get on to how to clean your carburettor, let's start by understanding where this part is on your lawnmower and what it does for your engine.

The carburettor on your mower is responsible for mixing fuel and air and is located directly on the internal combustion chamber of your lawnmower. When you have an issue with the carb on your mower, it can cause it to give start-up issues.

Problems tend to occur with the carburettor if it's been left in storage for a long time or dirt has got into the device, causing it to become blocked and in need of a clean.

Where Can I Find It?

The carburettor on your lawnmower is always located behind the air filter on your mower, once you find the air filter (which most likely has a black plastic cover), you can then locate the carb which is in the shape of a metal bowl behind the housing of the filter.

Common Symptoms Your Lawnmowers Carburettor Needs Cleaning

If you are not sure whether or not your mower's carburettor needs cleaning then looking out for these common signs that can help you identify a blockage within your mowers carb.

  • Your engine is having issues starting - A jumpy start or no power at all from your mower is a sure sign you need to give your mowers carb a good cleanout.
  • Unstable speed when mowing - A blocked carb or one in need of a repair can cause your mower to have choppy and an intermittent speed while running.
  • A fuel leak - Too much fuel or fuel with no exit will result in a leak from the engine.
  • Overheating - A bad ratio of fuel and air from a blocked carburettor will cause the engine of the lawnmower to potentially overheat.
  • Black smoke - Black smoke can be caused by the carburettor using too much fuel from the engine.

Why Do I Need To Clean My Mowers Carburettor?

A mower carb operates with air suction meaning it is very easy for dirt and other materials to get sucked in, you should clean this part of your mower once a year to prevent this from forming a blockage in your carb and causing further damage to your mower which will be harder to fix down the line.

How To Unclog a Lawnmower Carburettor

Now we know where the carburettor is on your mower, what it does and some signs it might be blocked, we can get on to our step by step guide of how to clean and unblock the carburettor with just a few tools and around thirty minutes of your time.

Tools Needed

  • Screwdriver
  • Cleaning spray
  • Socket wrench

Step One - Double Check The Carb

Before we start removing things and cleaning the carburettor on your mower, make sure that there is an issue. You can check if there is a fault with your lawnmowers carb by looking at the symptoms above and trying to lubricate it with an aerosol lubricant, if this doesn't work then move on to the next steps below.

Step Two - Let It Cool & Remove Air Filter

Make sure your lawnmower is completely cool before removing the air filter, also take off the spark plug to prevent any accidental start-ups from happening. Use a screwdriver to take off the air filter.

Step Three - Deattach The Carburettor

After removing the air filter we can get on to taking off the carb, to remove this part from your mower disconnect the fuel tube and use the socket wrench to remove any bolts on the carb.

Make sure you have a container to catch any fuel that comes out from the carb during this process, if no fuel drains out then you could potentially have a block in the fuel tube.

Remove the bolts that are holding the bowl to the carburettor and give it a good clean, use a small steel wire for any small holes.

Step Four - Have a Look A The Float

Take a look at the float which will be under the bowl, make sure everything is flowing free, if not then you could potentially have to replace it.

At this stage, you can also take your carburettor cleaning spray and use it in any holes you see around the parts, unclog any dirt or debris, then reattach the fuel tube and put all the bolts back together to make sure everything is secure.

Attach the spark plug back to your mower and see if the issues on your carburettor have been solved.

How To Clean a Lawnmower Carburettor Without Removing

For people who are short on time or don't want to be messing around with removing complicated parts from their mower, you will be happy to know there is another way to clean and unclog your mowers carb without having to remove it.

We have listed the steps below.

  • Step One - Ensure your mowers is cooled down then unscrew your air filter cover to expose the carb and its inner parts.
  • Step Two - Use your high-quality carburettor cleaning spray and start in the centre of the device spraying everywhere you can, including any small holes which are easy to miss. Remove any dirt deposits that have built up in the lower part, you can also spray some on to the choke shaft of your mower.
  • Step Three - Replace the cover and linkage on the carb then screw back on the air filter, check all the parts are where they originally were on your mower then start it up once again and sees if it works.

Should I Repair Or Replace The Carburettor On My Mower?

If your lawnmowers carb still isn't functioning after unblocking it, you may be wondering whether you should just buy a replacement or try to repair it, in this case, we recommend repairing it or taking it to a professional for it to be repaired.

Both methods don't cost too much, so if you don't mind doing some DIY, you can fix it yourself without having to install a replacement.

Frequently Asked Questions About Cleaning a Clogged Carburettor On a Lawnmower

How much would it cost to replace a carburettor on my mower?

It shouldn't cost more than £50 to buy a new carb for your lawnmower but may total to nearly £100 with other tools (DIY), it may be a good idea to get a cleaning kit for it too to make the job easier in the future.

Is it possible to damage the carb on a mower when cleaning?

Yes, by using a bad cleaner you could potentially do more harm than good when cleaning the carb, also make sure to put all the parts back in the right place after cleaning such as the air filter, failure to do so could cause even worse problems in the mower.

How much would it cost to rebuild a carb rather than replace it?

To rebuild the carb it could cost around £30-£150 if you get a professional to do it, re-building your carb can be a little complicated in comparison to replacing it so you should be sure you know what you are doing before attempting it.

When should I be cleaning the carburettor on my lawnmower? 

You should be giving your mowers carb a clean at least once a year, more is ideal if you are using your mower often or see any of the blocked carburettor signs.

Final Words

To conclude, cleaning your lawnmowers carb should be pretty easy if you follow the basic steps above in our guide, choosing the method of using a spray to clean it is much quicker than removing the whole bowl, and will also mean you don't have to worry about taking off lots of parts.

Always ensure that you put everything back correctly after you have cleaned the carb, never attempt to touch it until the mower has cooled down and always remove the spark plug when identifying the issue first of all.

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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