Push mower carburetor adjustment. How To Adjust Carburetor On Briggs and Stratton Riding Lawn Mower

Where is the Carburetor on a Lawn Mower? (Every Mower)

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I’ve always enjoyed using my cordless walk-behind push mower – no pesky cord to haul around and no gas to fill in the tank. But when I need a surge of power to complete larger jobs with ease, my go-to choice undoubtedly is my robust 140cc Briggs Stratton gas push lawn mower.

The downside however of using a gas-powered lawn mower is maintaining the many different parts like the air filter, spark plugs, hoses, and several other parts under the hood including the lawn mower carburetor.

Of all these aforementioned parts, the lawnmower carburetor is often the most overlooked but is in fact one of the most important parts of a mower just like a lawn mower engine that requires a fair bit of maintenance including annual maintenance.

What is a LawnMower Carburetor?

All gasoline-powered lawnmower engines are fitted with a carburetor. Similar to your car or truck engine, a carburetor helps run the small engine of a push lawn mower, self-propelled lawnmower, or riding lawnmower.

What Does a Lawnmower Carburetor Do?

The only goal of a lawnmower carburetor is to ensure that the right mixture of fuel and air enters the engine cylinder to trigger combustion.

This component of a lawnmower adjusts the balance of air and fuel based on myriad different factors including the amount of time the engine has been running, your speed, and the type of terrain you’re mowing.

Unlike automobile systems, a carburetor of a lawnmower doesn’t contain any throttle butterflies (a pivoting flat valve controlled by the gas pedal) but contains a rubber-type push bulb, through which fuel is primed when the bulb is depressed several times on a push-type lawnmower.

The fuel from the fuel tank flows through the bulb via a hose into the carburetor, which typically allows gas to drip into the carburetor bowl.

The engine creates a suction on the carburetor which mixes the gasoline with air at a specific ratio. After the carburetor has been primed, you can use the pull rope to start the engine.

What Does a Lawnmower Carburetor Look Like?

Most lawnmower carburetors look similar, with a small metal component complete with levers and springs and a distinct bowl shape under the carburetor body.

The carburetor float bowl accommodates the fuel and provides a continuous supply of fuel to the carburetor mixture as required.

The float bowl of a lawnmower carburetor can be drained with either the onsite drain bolt or screw without dismantling the whole system.

Where is the Carburetor on a Lawnmower?

This depends on the type of lawnmower you’re using, whether push, self-propelled, or riding lawnmower.

Where is the Carburetor on a Push Lawnmower?

Just as the name suggests, a push mower is any type of mower that you walk behind and push. The carburetor of a push mower is tucked away neatly behind the air filter at the side of the machine.

If you can locate the air intake filter or air filter of a push lawn mower, you’re one step closer to finding its carburetor. Depending on the machine, the air filter of a push mower is typically encased within a metal or plastic shroud and secured by a screw or with snap fittings.

Where is the Carburetor on a Riding Lawnmower?

The carburetor of a riding lawnmower is located just beneath the hood under the engine blower assembly so you’ll have to undo the hood latches of the engine hood to access it.

Similar to walk-behind mowers, the carburetor of a riding lawnmower is located behind or below the air filter, so once you remove the filter, you can spot it easily.

Signs a Lawnmower Carburetor is Dirty or Damaged

Old Gasoline

Old gasoline is the biggest enemy of a lawnmower carburetor regardless of the type of engine whether Briggs Stratton or brands including John Deere.

Your lawnmower will still run on old gasoline but it won’t offer the same top-notch performance that you’re used to.

This is why it’s highly important to empty the lawnmower gas tank when storing the machine for the off-season because old gasoline creates what is known as shellac in the fuel system.

This shellac blocks the inner workings and the air and fuel jets in the carburetor, which further prevents the fuel and air from passing through it.

A clogged gas line can be detrimental to the entire fuel system including the fuel filter, and mower air filter, and may even emit black smoke, which indicates that the machine is “running rich,” or burning too much gasoline.

The only solution for a gummed-up carburetor is a thorough cleaning, which involves removing the carburetor – a task you can do at home rather than visiting a lawn mower engine repair shop.

How to Get Rid of Old Gas in Lawnmower?

Before getting rid of the old gasoline from the lawnmower, check to see if it’s contaminated by pouring some in a glass container, pouring some fresh gasoline in another container, and then comparing them alongside.

If the old gasoline is darker or has a sour smell than the fresh gas, it is probably losing or has lost its efficacy.

Ideally, it’s best to get rid of the old gasoline from the lawnmower completely, but you can try diluting it with fresh gasoline to see if the performance improves.

You can transfer the old gasoline from the machine with a funnel into a jerry can or plastic can jug.

Engine Won’t Start

There could be several reasons why your lawnmower engine won’t start, most notably a dirty air filter, loose, dirty, or disconnected spark plug, and/or fuel not reaching the engine, which may be caused by a faulty carburetor or fuel filter.

If you’ve cleaned the air filter and checked that the spark plug and spark plug cable are connected securely, and you’re still facing the issue, making a few adjustments to the carburetor may help.

There may be many issues with the carburetor such as it’s dirty, the diaphragm is cracked or distorted, and/or it’s simply not getting the proper mixture of air and gasoline.

Your lawnmower’s carburetor and engine are protected against debris, dirt, and grass clippings by air filter guards. It is always a good idea to ensure they are clean and in perfect working condition:

• Check and clean the air filters and reinstall them in the machine.
• Next take a look at the vented fuel cap, which is designed to release pressure, allowing fuel to flow from the tank to the carburetor. Remove the gas cap to break the vacuum, then reattach it to see if this resolves the issue.

Engine Hunts at Idle or High-Speed

If your mower revs erratically, also dubbed as hunting or surging, the most likely cause is an incorrectly adjusted carburetor.

The good news is that most lawnmowers including John Deere have two screws that allow you to make adjustments to the carburetor yourself.

One screw adjusts the idle mixture while the other controls the idle speed. Since every lawnmower is different, refer to your owner’s manual for the location of the idle adjustment screws, start the mower and allow it to run for roughly 5 minutes, and make the screws looser or tighter until the machine runs and idles smoothly.

Lawn Mower Leaking Gas

A lawn mower leaking gas could mean several maintenance issues such as an open carburetor cover, carburetor housing, or carburetor float.

Another reason for carburetor fuel overflow is a stuck carburetor float, which is engineered to regulate the flow of fuel into the carburetor bowl through a simple mechanism.

There are a few potential fixes for this issue including adding a carburetor cleaner to your fuel, tapping the carburetor bowl light with the rear end of a screwdriver, and blowing compressed air through the carburetor bowl drain hole.

Engine Lacks Power at High Speed

Apart from old, bad fuel, another reason why the engine of your lawnmower may lack power at high speed is a dirty carburetor. In most cases, cleaning your lawnmower’s carburetor should resolve the issue.

How to Clean Lawn Mower Carburetor?

Experts say that you should check and clean your lawnmower’s carburetor at least a few times a year. The reason for this is simple – as you use your mower, grass, twigs, and other debris can make their way into the lawnmower’s carburetor, and eventually into the engine.

However, your carburetor will suffer breathing issues if the air filter is dirty, so the first thing to do is check the air filter to ensure it is free from any dirt and debris.

How to Find Your Lawmmower’s Carburetor?

Since every lawnmower isn’t built the same, the best way to find your mower’s carburetor is by referring to the user guide that came along with the machine. But here are a few simple steps to locate the carburetor of your lawnmower.

Before getting started, it’s important to ensure that the mower is in a stable position and safe location and will not roll off.

• Place the mower on a flat surface and make sure it is turned off completely. If you’re trying to locate the carburetor of a riding lawnmower, set it in a gear or engage the parking brake just like you would when parking a vehicle on a slope.
• Next, release anything that is making the mower’s internal components inaccessible such as hood latches. Most, if not all push lawn mowers don’t have a hood so can skip this step. This step applies to riding lawnmowers.
• Locate the air intake and the air filter, which are usually found on the side or top of the engine. The air intake and filter are set within a housing, which is either square or round shaped and has slits or holes in the top.
• Detach the filter housing which is attached to the carburetor via latches or screws.
• Locate the fuel line that comes from the gas tank to the carburetor. Undo the small clamp to detach the fuel line from the carburetor.

How to Remove a Lawnmower Carburetor?

To clean a lawnmower carburetor, you’ll have to completely remove it from the machine. You can usually do so with tools such as an adjustable wrench and/or a pair of needle-nose pliers. You may have to remove the engine cover as well depending on your lawn mower model.

• Turn off the fuel valve or make a crimp in the fuel line, and remove it from the carburetor. A little fuel may spill out at this time so you should dress appropriately for the job.
• Detach the choke and throttle linkages from the carburetor throttle lever, and remove the carburetor from the mounting bolts using a sliding motion.
• Unthread the screw to remove the carburetor bowl.
• Release the float pin and carburetor inlet needle.

How to Clean a Lawnmower Carburetor?

Once you’ve removed the carburetor from the lawnmower, you can use a carburetor cleaner to remove grime and fuel, and a dry rag to clean the external parts of the carburetor.

If you notice any signs of rust, get rid of them with sandpaper or a rust remover. Allow all the parts to dry and reinstall them and the carburetor back on the lawn mower.

If your carburetor is showing signs of physical damage, you may have to replace it with a new one instead of reinstalling the old one back on the machine.

How to Clean Lawn Mower Air Filter?

If you keep your lawnmower’s air filter clean, you will have less dirt and debris getting into the carburetor.

Your lawn mower’s air filter is in fact the first line of defense against dirt and debris that stems from the mowing process and prevents dirt from entering the engine via the carburetor.

It’s a good practice to clean your lawn mower’s air filter every 25 working hours or whenever you notice a dip in performance. Replace the air filter if damaged or after 300 hours of operation.

• Shut down the mower before getting started with the cleaning process, and make sure all the parts have come to a complete stop and have cooled down. Note: You should never operate a mower without an air filter as doing so will cause serious damage to the machine and yourself.
• Disconnect the spark plug wire and remove the protective screw that secures the mower’s shroud (covering) over the air filter. The exact location of the air filter could vary by model but most commonly is located near the top of the engine, and is protected by a shroud.
• Remove the air filter and take a closer look at it. Your lawnmower could be fitted with one of three different types of air filters:

• Foam air filter
• Paper air filter
• Dual-element air filter.

If you have a paper air filter, gently tap it on a flat surface to knock off any loose dirt and debris. Next, hold it up to a bright light source and if the paper blocks a considerable amount of light, then it’s time to replace it but don’t try and clean it further.

A foam lawn mower air filter should be replaced if there are any signs of crumbling or visible brown or yellow staining. If it’s in good condition, you can go ahead and clean it.

For a hybrid air filter, refer to the manufacturers cleaning guidelines. But usually needs to be replaced if it’s become stiff, brittle, or significantly stained.

Cleaning a Lawnmower’s Foam Air Filter:

• Washing: You can wash your lawnmower’s foam filter in the wash sink or with a garden hose to get rid of stubborn dirt. If it’s extremely dirty, use dish detergent to remove the dirt but be sure to rinse the soap out thoroughly.
• Drying: Let the filter air dry under the sun, after which you can oil it. You can apply oil with your hands or directly pour it over the foam filter. But don’t get carried away as you don’t want the oil dripping into the mower.
• Re-installing: Before reinstalling the air filter, clean the housing and the shroud with a dry cloth and not with a compressor because it could force dirt and debris into the carburetor and engine. Reinsert the air filter and make sure it fits snuggly into its dedicated slot. Lastly, replace the shroud but be careful not to tear the filter. Don’t forget to reconnect the spark plug, so you can start your lawnmower.

How to Perform Lawn Mower Maintenance?

Maintaining your lawn mower will improve both its performance and service life. Lawnmower maintenance can be carried out at any time of year but the two best times are before the first mow of the season and at the end of the season when it’s time to retire the mower.

Many people choose to take their mower to a professional repair shop for maintenance but these simple checks and fixes can be performed in the comfort of your home.

Since every lawnmower model is different than the other, it’s best to refer to your owner’s manual for maintenance instructions but here are some common tips to keep your mower in tip-top shape.

Replace the spark plug

Removing the spark plug ensures that the mower doesn’t accidentally start. A lawnmower spark plug should be changed every mowing season, after 25 hours of use, or if the mower won’t start.

• Start by disconnecting the spark plug lead.
• Clean the area to prevent any debris from seeping into the combustion chamber when you remove the plug.
• Use an appropriate spark plug socket to remove the spark plug.
• If there are any light deposits on the plug, clean them with a soft cloth.
• Replace the plug if there are any damaged electrodes.

Change the oil

You should ideally change the oil in your mower every 50 hours of operation or after every mowing season. Most mowers come with a drain plug that allows you to drain the oil from the mower. If your mower didn’t come with a drain plug, simply flip the mower over on its side and allow it to drain via its fill hole.

Make sure to replace the oil with the right type of lawnmower oil, but 10W30 is the grade suitable for most lawnmowers.

Drain the fuel tank

If your lawnmower won’t start, the common culprit is old gas. Lawnmower gas can go stale and lose its volatility in as little as 30 days and leaving gas in the tank when not in use can eventually corrode the fuel tank.

Remember to drain the fuel tank at the end of each season and refill it in the spring, and take all the necessary precautions while performing this task.

Clean the mowing deck

The mowing deck is perhaps the most used component of a mower but is also the most overlooked when it comes to cleaning and maintenance.

It’s a good practice to clean the mowing deck every time you finish cutting the lawn. Dirt, cut grass, and debris can accumulate onto the area above the blades, aka the mowing deck, and once it dries, becomes incredibly hard and difficult to remove.

You should perform a thorough mower deck cleaning at the end of the growing season, which entails removing the spark plug and cleaning the mowing deck and blades thoroughly.

Check the tires

Regardless of the type of mower, whether walk-behind mowers or riding lawn mowers, it’s important to check the tires to ensure they’re in good condition and are free from chips and damage.

Here’s an informative video on how to remove a lawnmower carburetor and the steps to maintain and repair a lawn mower:

How To Adjust Carburetor On Briggs and Stratton Riding Lawn Mower

Briggs and Stratton is an engine manufacturing company, and these engines are mostly used in powered garden tools such as lawnmowers. These Briggs and Stratton engines are gasoline-powered. So it uses gasoline as a power source to propel the mower and turn the blades for cutting grass.

Briggs and Stratton gasoline engines are designed with a carburetor that controls the gas flow from the task to the engine. Over time the carburetor can be malfunctioned, and cause the mower to perform significantly less optimal. Proper knowledge about how to adjust carburetor on Briggs and Stratton riding lawn mower can help you to adjust the malfunction carburetor very easily.

Why Carburetor Need Adjustment?

The carburetor controls the gas flow, so if it does not work properly, the engine will not be fueled. Fuel is what powers the engine, and without fuel, the engine is unable to function. There are a number of other reasons, and some of these are-

• The primary intention behind adjusting the carburetor is to make sure the engine runs smoothly. A properly adjusted carburetor makes sure ideal engine speed when the engine is idle, making the engine helps to run smoothly.

• For ensuring proper air, and fuel mixture when the mower engine is idle, it is mandatory to have a properly adjusted carburetor.

• The carburetor, in a manner, controls the way a lawnmower will behave when it is in an idle position. So if the engine is behaving or running roughly, adjusting the carburetor will ensure the engine runs smoothly when at idle position.

The carburetor is not digital, so it cannot adjust itself. You have to adjust the carburetor manually to make it work perfectly.

Carburetor Adjustment Safety

The carburetor adjusting process is not so risky but no process is 100% safe. It is easy to notice the good sides of a process, but we often overlook the process’s risk. Mostly you’ll be working with the baseline, but in between in the process, you have to start the engine. So, for preventing any sort of accident, you should follow these safety tips-

• If your mower is very old, then the first thing you have to ensure that there is no fuel leakage. If you find any fuel leakage, then seal the leak appropriately or cause a backfire on the manifold.

• You’ll not be working near the engine fan, but still, you have to keep an eye and keep your finger away from the engine fan. If your fingers get near it, then the fingers can get seriously injured.

• Before starting the procedure, make sure that no part of the engine is hot. Stop the engine, and wait for some time to make the engine cool. Hot engine parts can cause you to get second or third-degree burns. Also, make sure the carburetor also does not get near any hot engine part.

You are working around chemical and running engine parts. So use gloves and goggles to be safe from any type of hazard.

How To Adjust Carburetor On Briggs and Stratton Riding Lawn Mower Step-by-Step Process

The carburetor controls idle speed and high speed. Let’s learn to adjust all of these.

Tools you’ll need to complete the process-

Adjusting the carburetor does not include any heavy tools, and it is very easy to do as well.

• A screwdriver– you’ll need this tool to adjust the screws.

• Gloves and goggles– These two tools will ensure safety while you will adjust the carburetor.

Adjust Idle Speed Mixture

Step-1: Turn of the engine

Ensure the engine is not running and shut off the engine at least 5-10 minutes before starting the procedure. Allow the engine to cool, and it will be easy to work with the carburetor.

Step-2: Remove the air filter

On top of the mower engine, there is an air liter. Locate it and the air filter cartridge. The filter is attached to the engine using some nuts. Loosen those, and remove the air cartridge and filter from the engine.

Step-3: Clean the carburetor

After removing the air filter, if you may see dust inside the carburetor, you can use a carburetor cleaner or compressed air to clean that.

Step-4: Adjust idle screw

Locate the idle screw, and use a screwdriver to adjust it. Turn the screw clockwise using the screwdriver until the screw’s needle touches the seat. After that, turn the screw counterclockwise with the screwdriver 1 turn.

Step-5: Adjust the high-speed screw

Along with the idle screw, high-speed screws also need adjustment. Use a screwdriver clockwise until the screw’s needle touches the base. Then, use the screwdriver counterclockwise, and turn the screw 1 turn.

Step-6: Replace the air filter

After adjusting the screws, place the filter and cartridge at the place, and tighten those nuts that you have loosen before to secure the cartridge and filter. No need to put the cover back now.

Step-7: Start the engine

Now, start the engine of your mower, and make sure it is running on half throttle. Allow the engine to run for 5 minutes to warm it up.

Step-8: Fine-tune idle speed

You may see the engine running roughly. To make it run slow, turn the idle screw clockwise. Note at what point the engine is running slow. After that, turn the idle screw counterclockwise, and it will start to normalize. Continue turning it until you find a spot where the engine runs slow again.

Place the screw in the middle of these two points to get the best control over the engine at the idle position. The best idle speed for an aluminum-block engine is 1750RPM, and an iron-cast block engine is 1200RPM.

Step-9: Fine-tune high-speed screw

Set the throttle to fast from half. Turn the high-speed screw to your right until the engine gets slow, and note the point. Repeat the process counterclockwise, and note the point where the engine runs slow. Now set the screw at the center of these two locations for getting the best result.

Step-10: Test the lawnmower

Now use the mower in various conditions, and see the engine is running smoothly or not. If not, then fine-tune the idle and high-speed screw, and you’ll surely get the desired result.

Frequently Asked Questions

What can cause a lawnmower engine to run roughly?

Sometimes a very little thing like airflow issues can cause the engine to run roughly. To get the engine to run smoothly again, adjusting the carburetor will do. Adjusting the carburetor will make the air and fuel flow properly, which will help to run the engine smoothly.

How Can I adjust the carburetor on a riding lawnmower?

For adjusting the air-fuel mixture, you have to adjust the idle and high-speed screws. Use a screwdriver to adjust these screws and set those at an ideal position. After that, the air-fuel mixture will work fit and fine.

Final Words

After knowing how to adjust carburetor on Briggs and Stratton riding lawn mower, it is very easy. Adjusting the carburetor does not kill a lot of time, and by spending a little time, you can quickly fix your engine carburetor.

Even after using the fix, if the engine still behaves roughly, you should see a professional. This solution should work in most cases. But if the mower is very old, you should take help from a professional to avoid all types of risks.

Read Our Latest Article:

How to Adjust Carburetor on Briggs and Stratton Riding Lawn Mower

It is important to perform regular carburetor maintenance to prevent future hassle down the road. If debris has accumulated in your carburetor’s main fuel jet, use compressed air to blow out the loosened debris and carburetor cleaner to clean. Using a carburetor cleaner can reduce the amount of maintenance, repairs, and downtime you have to deal with while improving the starting of all 2-cycle and 4-cycle engines.

An engine’s carburetor is responsible for directing gas flow between the tank and the engine. When the carburetor is not adjusted correctly, the engine and mower will perform less than optimally. It is possible to adjust the carburetor to adjust the speed, the high speed, and the choke.

Adjusting the Carburetor on a Briggs and Stratton Lawn Mower, Step by Step

Your Briggs and Stratton lawnmower carburetor may need to be adjusted for various reasons. Whatever the reason is, you must adjust the carburetor to its maximum performance if you wish to fix any of these problems.

There are some important tools that you will need for the job. They are-

• Set of Pliers
• Screwdrivers
• Wrench
• Carburetor cleaner
• RPM gauge or tachometer
• Pair of safety gloves

The steps to adjust the carburetor on a Briggs and Stratton lawn mower are given below:

Step 1. Prepare the Lawnmower

In the first step you should park your lawn mower somewhere safe and open and has enough light. The soil should be even and it is better not to do it in the garage. Start your riding mower engine and let it warm up for 5 to 7 minutes. The slow position of the choke lever will bend your mower into the shape of a turtle. At this idle position, listen to the engine noise. Take note of the speed and sound of the engine again after you run it.

After the engine has cooled down, turn off the ignition. Obtain the tools needed for the repair. To prevent the mower from rolling, set the parking brakes in position and set the gear to neutral.

Step 2. Adjust the idle speed mixture

On top of the riding mower engine, place the air filter and air filter cartridge. Remove the air filter and cartridge after the engine has been cooled down and the nut has been loosened. For clearing out accumulated debris and gunk in the carburetor, Gumout recommends spraying carburetor cleaner onto the carburetor. On the carburetor, you will find a screw for adjusting the idle speed. By turning the screw with a screwdriver counterclockwise until the needle just barely touches the seat, tighten the screw. Next, turn it in a counter clockwise direction 1 1/2 times.

Step 4. Adjust the high-speed mixture

In this step you have to adjust the high speed mixture. In order to do so, you must find the high speed adjustment screw which is on the opposite of the idle speed adjustment screw. Carburetors that are older or made by a particular manufacturer may not have the option of adjusting the components. In that case, remove the air filter cover, filter, and cartridge to access the carburetor.

Starting the engine and letting it run for a few minutes to warm up will prevent the engine from stalling. As you turn the high speed screw clockwise, make sure that it touches the seat with its needle. Now turn the screw counterclockwise 1 1/4 turns. But be careful of the cautions of Briggs Stratton.

The mower will now start when you set the throttle to fast. You must first turn the high speed screw clockwise until the engine slows, then counterclockwise until the engine slows. Now, you need to determine the location of its center. Test the adjustment by moving the throttle from slow to fast and back again. Finally the cartridge, filter, and cover should all be mounted on the mower. And you are done with this step!

Step 5. Adjust carburetor choke linkages

Locate the choke linkage on the carburetor by removing the air filter cover, filter, and cartridge. Press the fast accelerator pedal.

You will need to loosen the bracket that holds the throttle cable casing in place. Release the cable by loosening the screw on the bracket using a screwdriver without taking it completely out.

Using your fingers, move the cable until the carburetor’s choke plate closes. Secure the cable in place by tightening the bracket against the cable casing. The carburetor choke plate will open and close as the throttle is moved from fast to slow, then back to fast.

Step 6. Check the carburetor connections and engine speed

Having cleared the carburetor flow lines is an important step after mixture adjustment. For this reason, ensure the fuel line, air intake, and exit are clean and free of obstructions. Clean them with petrol and dry them in the sun afterward. They can be closed in the same manner as they were opened. Install the tubes properly. Now, start the engine.

If all the steps have been followed correctly, then you have adjusted the carburetor of your Briggs and Stratton engine correctly.

Final Words

So that was all about how to adjust the Carburetor on Briggs and Stratton riding lawn mowers. If you still face any problems even after following the steps you can contact an expert.

How To Troubleshoot a Lawn Mower That Revs Up and Down

Have you ever experienced a situation where your lawn mower suddenly started revving up and down? If yes, you might have wondered whether it is possible to troubleshoot this issue, and if possible, you must have thought about how to troubleshoot such a problem.

Firstly, gather up all the necessary tools and materials. Now, inspect the current state of the Spark plug, Fuel system, Air filter, and Fuel Filter. Next, remove the full Carburetor setup to clean, repair or replace the faulty elements and reinstall everything.

Keep reading the following article and learn details of how to troubleshoot a lawn mower that revs up and down.

What Causes the Problem?

A lawn mower might rev up and down due to faulty or blocked airflows. The most common reasons behind mower aggressive revving trouble are defective spark plugs, faulty spark plug lead, clogged air filter, and fuel filter.

Issues with fuel lines, fuel tank, wrong carburetor adjustment, or faulty internal elements of the carburetor can also cause your lawn mower to experience surging or revving problems.

However, it is hard to confirm any specific culprit without performing a thorough inspection.

Therefore, continue to check on every potential part or internal component until you reach the core of the main issue.

Steps to troubleshoot a Lawn Mower that revs up and down:

When the lawn mower lacks a sustained speed due to insufficient fuel or air, it will encounter aggressive revving issues.

This mostly ends up with the mower engine shutting down abruptly while operating.

It is a common issue that most lawn mower users encounter as their mower gets older or due to a lack of regular maintenance.

As soon you encounter such commotion, you should immediately check what went wrong and fix the problem. Otherwise, this issue can eventually cause more damage to your mower.

To guide you on that task, I have prepared a quick and easy DIY method of troubleshooting a lawn mower revs up and down.

Things needed to troubleshoot a lawn mower revs up and down:

Before moving to the step-by-step troubleshooting procedures, have a proper glance at the checklist of the required tools and materials:

Step 1- Check the Spark plug, Fuel system, Air filter Fuel Filter:

First, check whether the gas tank is plugged or fuel has any issue. If this area has any issues fix them and if not, then move to the next part.

These two videos will guide you to troubleshoot your mower fuel system issues:

Next, check the current state of your spark plug and repair or replace it as required.

This video will guide you to check, clean, or replace the spark plug easily.

You should also inspect your lawn mower’s air filter and fuel filter. If necessary, replace both filters and for that, these two videos will guide you:

Step 2- Remove the full Carburetor setup:

You can take pictures of every single step of this particular task so that when you will reinstall everything, you will not make any mistakes.

First start the task by removing the entire air cleaner assembly.

Then, remove all the linkage cables attach to your mower’s carburetor.

Next, turn off your fuel supply or drain your fuel tank.

After that, remove the fuel line from the carburetor.

Or, drain the gas leak from the bottom.

Take these two nuts off and slide the carburetor off the main support ports.

After removing the carburetor, remove the float bowl and float pin.

Also, take the float needle valve off.

You can find the main jet right inside this area where the float was.

The main jet will look like the above image once it is removed.

You will also find the pilot jet from the same area and remove it.

Now take the emulsion tube off.

Remember, you can take off all the above-mentioned parts by using a proper sized flat headed screwdriver.

Step 3- Clean, repair or replace the faulty elements and reinstall everything:

Once you have removed the carburetor and all the connecting parts or elements, it’s time to clean every single thing thoroughly with a Carburetor throttle body cleaner.

Make sure there will not be a single hole or part of the carburetor blogged or clogged and not open.

While cleaning the entire carburetor setup, you can also inspect for the broken or severely damaged components. If required, replace the faulty parts.

After that, put everything back together as they were before and test whether your mower is still having the same problem or it’s working fine now.

If any of the above-mentioned techniques didn’t solve your issue, immediately contact the nearest dealership for professional assistance.

Performing such repairing tasks can be hazardous. Thus, make sure you have enough knowledge and expertise to perform them. Remember to first read your mower’s instructions manual before operating, servicing, or troubleshooting it.

Frequently Asked Questions: Lawn mower revs up and down

What causes a lawn mower to pulsate?

If your lawn mower has suddenly started to pulsate, the most common reason behind this commotion can be a clogged fuel supply, bad/old gas, defective spark plug, or faulty carburetor.

What causes a lawn mower rev to bounce aggressively?

Due to an automatic transmission leak or fluid levels falling, your lawn mower rev can bounce like that.

What causes a lawn mower engine to idle up and down?

The most obvious culprit for causing such trouble is a bad idle air control valve. But to confirm the issue, check the engine light first.

What caused my lawn mower engine to shake at idle?

Weak or broken mounts on the lawn mower engine can cause such trouble.

Final Verdict

If you ever experience similar issues while operating your lawn mower, try the above fixing tricks.

Initially, those techniques might seem a bit complicated to perform, but if you have minimum mechanical expertise and follow the steps thoroughly, you can easily get rid of this issue in no time.

If you want the best result, you have to thoroughly follow all the instructions for troubleshooting a lawn mower that revs up and down without skipping any detail. So, keep that in your mind.

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Where is the Carburetor on a Lawn Mower? (every mower)

Do you need to do some troubleshooting or maintenance with your lawn mower? If so, you’ve probably wondered where the carburetor is on a lawn mower. The location of this component of your mower’s engine can vary depending on the type of lawnmower you have.

In today’s article, I’ll tell you what a lawn mower carburetor looks like, where it usually is found on every type of mower, and provide a list of cleaning tips to maintain your mower’s carb.

All About the Lawn Mower Carburetor

What it Looks Like, What Parts of the Mower it Connects to, and

The carburetor is an essential part of your lawn mower’s engine. It makes sure that the correct combination of fuel and air will go into the engine cylinder. This is essential for combustion to occur.

When the spark plug ignites the fuel and air mixture, it combusts and pushes the engine piston in a downward direction. This, in turn, rotates the crankshaft. This makes the lawn mower blade spin.

Depending on the type of lawn mower you have, the wheels of your mower (for example, a riding mower or self-propelled mower) will also start to rotate.

How to Find and Identify Your Mower’s Carburetor

The carburetor is part of the mower’s engine. Typically, it is bolted to the side or top of the engine. It is also connected to the gas tank, and will typically be located just below or behind your air filter. Most lawn mower manufacturers make the air filter housing easily accessible and easy to identify so that owners can change out the filter as part of their annual maintenance. Find the air filter and your mower’s carburetor will be the next part of your mower’s engine, right behind it.

While the location will vary by manufacturer, there are a few qualities most carbs share to make them easier to identify.

Carburetors are metal and rectangular in shape. Your mower’s carb will often have black areas, such as a black circle and trim on the right and left.

In this article I’ll walk you step-by-step through locating and servicing your mower’s carburetor, with specific tips for locating the carburetor on every type of lawn mower.

Different Kinds of Lawnmower

In this section, we will go over the different kinds of lawnmower and where you can usually find the carburetor in each. The two main kinds of lawnmower are walk-behind and riding.

Walk-Behind Mowers

There are four main types of walk-behind mowers, which I list below – if you own a walk-behind mower make sure you know which type it is so that you can refer to the correct part of this article to locate your mower’s carburetor:

• Electric walk mower: An electric walk mower is appropriate for smaller properties.
• Self-propelled mower: A self-propelled mower is handy because it propels itself, meaning it’s a lot less work when mowing hilly areas. If you get a self-propelled mower, you can choose front-wheel drive or rear-wheel drive. Front-wheel drive is suitable for level ground. A self-propelled mower with rear-wheel drive is most suitable for sidehill and uphill mowing.
• Two-function mower: A two-function mower mulches and bags as well as does the usual grass cutting.
• Three-function mower: A three-function mower cuts the grass as well as bags, mulches, and side discharges.

Riding Mowers

There are three main types of riding lawn mowers, which I list below. If you own a riding mower, make sure you know which type it is so that you can refer to the correct part of this article to locate your riding mower’s carburetor:

• Rear Engine Riding Mower: The rear engine riding mower is the smallest of riding mowers.
• Lawn Tractor: Lawn tractors (sometimes called garden tractors) have very powerful engines, which are great for large properties.
• Zero Turn Radius Mower: Zero turn radius mowers are also very powerful, but they are easier to maneuver.

Carburetor Location in Walk-Behind Mowers

For walk-behind mowers, you will find the carburetor at the side of the mower, in the area above the base of the mower. As we mention later, the carburetor is connected to the air intake and air filter of the mower. Therefore, finding these components makes it easy to find the carburetor.

If you’re having trouble finding them, search for square-shaped or round-shaped filter housing. This will generally be on the side of the mower’s engine, though it’s sometimes on the top.

The air filter case is usually plastic and pops open easily to provide easy access to the filter for maintenance. The mower’s carburetor is just behind the air filter’s housing, and there are typically 2-3 bolts that can be loosened to remove the filter housing and reveal the carb.

This video does a nice job demonstrating the removal and cleaning of the carburetor on a walk-behind mower:

The exact process for repairing or replacing a carburetor in a riding mower will depend on your exact model, and it tends to be more complicated than working with the carburetor of a walk-behind mower, so you may choose to hire a professional at a small engine repair shop to do this for you.

If you are going to do a carb repair or replacement yourself, my advice is to consult the manual that came with your machine, and document every step of the process so that you can remember how the carb was set up and have an easier time re-attaching everything properly.

Here’s a video from Sears that walks you through replacing the carburetor on a Craftsman Mower. It provides a good sense of what’s involved in this project, what your riding mower’s carburetor looks like, and where the carb is located on some riding mowers:

• Step 1: Turn off your mower’s ignition and use the parking brake. To stop any accidental rolling, put the mower in gear.
• Step 2: Make the mower’s engine accessible by releasing any restraining devices (such as hood latches) that are holding down the hood.
• Step 3: Find the air intake and the filter. You should find filter housing (square or round-shaped) on the side or top of the engine. This will have slits or holes in the top. The filter housing will be attached to the carburetor by screws or latches. This housing contains a filter made of foam or paper. The filter found within the housing is there to stop dust and dirt from getting into your mower’s carburetor.
• Step 4: Locate the fuel line that comes from the gas tank. You can use this information to find where the gas tank. Gas tanks will usually be mounted in a place that makes it easy to access for re-fueling and is often black.
• Step 5: Find the fuel line that comes from the tank. This line will usually be situated in close proximity to the bottom of the tank. A small clamp is usually there to attach it. You can trace the fuel line that attaches the tank to where it connects with the carburetor.

Why is it Important to Clean Your Lawn Mower’s Carburetor?

The carburetor of your lawn mower needs to be kept clean in order for the machine to work as it should.

Think of the carburetor in a car. If it isn’t kept clean and properly maintained, your vehicle will not run properly.

This is the same with a small engine such the kind you have in a lawn mower.

If you are having certain problems with your mower, there is a good chance that you need to clean the carburetor. Below are some signs of a dirty carburetor:

• You’re having problems with the engine stalling when you are trying to cut the lawn.
• You are having difficulty starting the mower.
• There is black smoke coming from the muffler.
• The engine is sputtering or running turbulently during mowing.
• You have noticed an increase in your mower’s fuel consumption, even though you are using the way you always have.

How to Clean a Mower Carburetor Once You Locate It

Let’s take a look at how to clean a lawn mower carburetor.

Please note that these are general instructions and you should consult with the instructions that come with your particular mower before you proceed.

Removing the Carburetor

• You must completely remove the carburetor from the lawn mower before trying to clean it.
• If it is necessary, take off the engine cover.
• Take off the cover of the air filter, the filter, and the housing of the air filter.
• If possible, turn off the fuel valve. If this isn’t applicable, make a crimp in the fuel line. After that, take it off the carburetor. Be ready for a bit of fuel to spill out. You can use a rag to deal with the mess.
• Get the choke and throttle linkages detached from the carburetor throttle lever.
• Use a sliding motion to remove the carburetor from the mounting bolts.
• If necessary, release the carburetor bowl by unthreading the screw. This will release the bowl.
• Release the float and needle by removing the float pin.

Cleaning the Carburetor

• To completely take apart the carburetor, you will possibly have to unthread screws so that the primer bulb and base are released. After that, take out the metering plate, diaphragms, and gaskets.
• The outlet ports and carburetor intake should be exposed. You should then use a special carburetor cleaner spray (if you don’t have that, then WD-40) to clean out residue from the ports.
• If there is a bowl, clean it out.
• Check if there are any signs of rust in the carburetor. If so, get rid of it with sandpaper.
• Give the carburetor time to dry. After that, put it back together. Ensure that the diaphragms, metering plate, gaskets, and primer base are correctly positioned. Also do the same with the float and float needle.
• Ensure that you put the bowl gasket back in its correct place. Reinstall it if that is necessary.
• Use a sliding motion to reinstall the carburetor onto the mounting bolts. Get the throttle linkages re-attached to the throttle lever.
• Reattach the carburetor to fuel line.
• Reinstall the air filter, filter cover, and air filter housing.
• If this is necessary, reinstall the engine cover.

What if the Carburetor Needs Repairs?

It is possible that your carburetor will need repair as well as cleaning. If that is the case, you can consider buying a carburetor repair kit. This will help you with replacing some of the major components of the carburetor, such as the diaphragms, gaskets, float, and float needles. You can probably find a kit that matches your mower on Amazon for less than 20.

If you find that the carburetor continues to have poor performance, it’s possible that you will have to get a new carburetor and replace the old one. The price of a replacement carburetor will typically be about 50, and you can find genuine manufacturer’s carb replacements on Amazon (like this one for a Honda self-propelled mower).

If you’re sure your lawn mower issues are the result of carburetor problems, it’s generally easier to buy a new carb and replacing the whole thing vs attempting to repair a few gaskets or parts.

In my experience a repair kit works better in theory than in practice, and your average weekend warrior is better off replacing the whole thing if determined to DIY a fix. For 30 more, why not install a brand new carb?

The other option (recommended for most people) is to take your mower to a small engine repair shop and let them do the work for you. This is less expensive than you’d think, and will save you some time and headaches.

For optimal lawn mower maintenance, you should clean the carburetor every year.

This will help your mower always perform at the optimal level and help to hold off problems that will require parts replacement or full replacement of the carburetor.

And you don’t have to take your carb out to keep it running like new – I give my mower a shot of Gumout Carb and Choke Cleaner (Amazon link) before every mow to keep it running like new. It’s like 5 a can and lasts a whole season.

Maintain Your Lawn Mower So It Lasts!

Understanding how your lawn mower works and how to maintain it is key to making it last.

Purchasing a new lawn mower is an investment, so it’s well worth taking the time to read the manual and understand all the components and their functions.