How to Fix a Sputtering Lawn Mower

Does your lawn mower keep on sputtering? Sputtering is a common problem that normally leads us to doubt the lawn mower brand we are using. Lawn mower sputtering is annoying but it can be avoided to great extent by keeping the lawn mower nice and clean. 

“How do I stop my lawn mower from sputtering?” Is a commonly asked question and a lot of people don’t get a satisfactory answer because the answer to this question can not be composed in one or two lines. There are several causes and only a specific treatment can fix the issue. 

Since this website is made to help both beginners and advanced lawn owners, we have decided to answer this most googled question in detail today. We all know that cure can only be found once the problem is identified, so let’s see what are the possible causes of sputtering and how they can be cured.

The most common causes of lawn mower sputtering

There can be many causes of lawn mower sputtering as they have to handle the messier and toughest job. There are a lot of other factors as well that contribute to this issue but normally the major causes of lawn sputtering are:

  • Clogged Air filter
  • Clogged fuel filter
  • Filthy carburetor
  • Cheap poor quality fuel
  • Improper gas cap
  • Damaged spark plug
  • Faulty carburetor
  • Water in the fuel tank
  • Dirty mower deck

Now that you know the major causes of lawn mower sputtering. Let’s discuss each problem-causing case separately in detail;

Lawnmower sputtering caused by a clogged air filter

clogged air filter issues

Clogged and dirty air filters do not just lose their ability to work properly but also affect the mower’s engine. The dirt interrupts the fuel flow, the improper fuel flow then simply becomes the reason for sputtering.

The air filters of lawn mowers get dirty easily because their job is messy but proper care can keep the airflow intact. The major symptoms of dirty or clogged air filters are reduction in horsepower, strange noise, and fuel smell. Moreover, the dirty air filter can also be judged by its appearance.

Keeping this problem aside, the lawn mower’s air filter should be cleaned and maintained properly because the thoroughly cleaned air filter prevents dirt from entering the engine to cause more serious problems.

Fixing clogged Air filter issue

The mower needs fresh and clean air to mix with gasoline to do the job. To supply clean air, you just need to examine the cap carefully. Replace the cap if it needs replacement and wipe off the dirt particles that are damaging the air quality.

Lawnmower sputtering caused by a clogged fuel filter

clogged fuel filter issues

Clean air and fuel filters keep the engine running smoothly. The dirty or clogged fuel filter affects the lawnmower engine the same way as an air filter.

The fuel filter can be changed or cleaned to prevent the lawnmower from sputtering. The clogged fuel filter interrupts the gasoline flow, the improper gasoline supply leads to sputtering and several other engine issues.

The symptoms of a clogged fuel filter are low oil pressure, noticeable metallic noise, and poor performance.

The oil filter can be cleaned but in the case of lack of lubrication, loss of oil pressure, and premature wear and tear it must not be cleaned but changed.

So, Not cleaning the oil filter from time to time or keeping it dirty for a long time not only causes sputtering but also damages the engine.

Fixing clogged fuel filter issue

The fuel filter may contain water instead of air and gasoline. Empty the fuel tank remove the moisture and allow it to dry. Once the fuel tank is dried refill it with ethanol-free gas.

Lawnmower sputtering caused by filthy carburetor

The filthy carburetor is another common problem that causes the lawn mower to sputter. The sticky by-products of hydrocarbon and combustion usually gather around in the carburetor leaving it filthy. Keeping the filthy carburetor impacts the engine’s performance by restricting the air and fuel supply.

The carburetor needs to be cleaned when it’s not working, flooded, running lean, or rich. Cleaning a carburetor is not a hard nut to crack as the gunky deposits can be removed without removing the carburetor.

Fixing filthy carburetor issue

To fix the filthy carburetor, remove the cap, drain the oil, and wipe off all the dirt and leave it open for a few hours.  As the carburetor is dried you can refill it up with the oil mentioned in the manual. The best way to clean the carburetor is by wiping off the filth with carburetor cleaner spray. Carburetors cleaners are readily available on Amazon and they perform their duty well.

Lawn mower sputtering caused by cheap poor quality fuel

The fuel that is available on the local fuel stations is good for cars, trucks, and other such vehicles but not for lawn mowers because it contains a noticeable amount of ethanol. Ethanol is harmful to the lawn mowers it shouldn’t be kept in the mower for a longer time.

If you have to use it anyway make sure you bring the mower back in the garage empty. Ethanol, no doubt, fuels the lawn mower to perform the mowing duty but on the other hand, it is burning the plastic parts that eventually lead to sputtering.

To prevent fuel from causing this problem, it is suggested to use ethanol-free gasoline to fuel the lawn mower engine. It might be expensive but it won’t harm this lawn-aiding vehicle.

Fixing the poor quality fuel issue

The lawn mowers generally do not mind refilling the gasoline from the local gas stations. The gasoline being sold at the gas stations is never meant for lawn mowers. To prevent your lawn mower from sputtering, remove the fuel and try refilling the lawn mower with ethanol-free gasoline.

Lawn mower sputtering caused by the improper gas cap

It sounds ridiculous but an improper gas cap can also cause lawn mower sputtering. The improper gas cap would either fill the gas with too much air or completely deprive the gas tank of it and both cases are dangerous for the lawn mower.

So, if nothing out of all the causes of sputtering is bringing the lawn mower’s performance down it is suggested to get the gas cap checked. If the gas cap is bringing it down, rest assured because this sputtering issue is the easiest of all to fix.

Fixing the improper gas cap

Once the gas cap is worn out or broken it’s impossible to be fixed. So, replace the worn-out cap with a new properly fitted gas cap to keep the lawn mower running smoothly.

Lawnmower sputtering caused by the damaged spark plug

A worn-out or damaged spark plug may not solely be the reason but it makes the situation ideal for sputtering. It’s better to replace the worn-out damaged spark plug immediately to minimize the chances of sputtering.

The sputtering can also be avoided by using branded spark plugs to kick start the lawn mowing operation. To keep the lawn mower in excellent condition, it’s better to keep changing the spark plugs every year.

Fixing the damaged sprak plug

Like a gasoline cap, an old worn-out spark plug can also not be fixed. Even if it’s not broken it’s better to replace the spark plug every year to minimize the chances of sputtering caused by the spark plug. If the spark plug is slightly dirty and you are not willing to replace it, it’s suggested to clean the dirtiest part with a wire brush to boost the lawn mower’s performance.

Lawn mower sputtering caused by faulty carburetor

faulty carburetor on a lawn mower

The filthy carburetor can not only be the reason for sputtering but choosing the wrong carburetor for your lawn mower can also cause the problem. The carburetor must run smoothly to keep the lawnmower functioning properly. Common carburetor problems like imbalanced air and fuel circulation and improper repair can also contribute to the common lawnmower issue called “sputtering”.

Fixing the faulty carburetor

The faulty carburetor keeps welcoming the sputtering issue. Take professional help and get the faulty carburetor replaced with the right one to nip the evil in the bud.

Lawnmower sputtering caused by water in the fuel tank

The fuel tank is supposed to hold fuel but if water gets mixed with the fuel it also causes the lawnmower to sputter. The water and fuel do not mix well so it can easily be noted whether the unmatched water and fuel chemistry is causing the problem or not. If one wants to keep the lawnmower running smoothly he/she must be careful with the fuel tank.

Fixing the water in the fuel tank issue

Air and fuel together keep the lawn mower functioning properly. If water tries to mess the air-gasoline relationship, remove the fuel wipe off the moisture,allow it to dry, and replace it with ethanol-free gas

Lawn mower sputtering caused by dirty mower deck

The lawn mower’s deck is also reputed to cause sputtering. Deck catches the dirt more than any other part of the lawn mower. The mower’s deck must be cleaned after mowing because the grass build-up doesn’t come off easily once it is dried. However, Sputtering can be avoided successfully by not letting the grass get bigger than the suggested length and using the lawn mower only when the grass is dried. 

Fixing the dirty mower’s deck

Lawn mower’s deck must be kept clean to keep the sputtering at bay. Scrape off the dirt and grass right after mowing. Paint it often with the mower’s deck paint to get it less affected by the dirt and grass.

These were the main causes and specific solutions of the lawn mower’s sputtering. There are several other minor issues as well that also contribute to sputtering so to avoid this annoying situation it is recommended to keep an eye on the critical points of the lawn mower.

Since there are several causes of sputtering and the problem is only minimized when the gardener is sure about the cause. It’s hard to suggest an all-in-one solution for this problem but the below-mentioned instructions would make it a lot harder for the lawn mower to sputter. 

The general way of fixing the lawnmower sputtering

It must be confessed here that this general way may help in bringing the intensity down but won’t fix the problem completely. So, let’s see what you have to do to minimize the issue;

Step one

The first step to prevent sputtering is to inspect the fuel. To inspect the fuel, remove the cap and see if there are signs of moisture or not. If this unwanted mixture is causing the issue, remove the fuel, let the tank dry and refill it with ethanol-free gas. 

Step two

Step two requires you to pay attention to the carburetor. Turn the mower over and drain the oil out and refill it with the oil that is mentioned on the manual. 

Step three

Now is the time to inspect the air filter. Remove the cap and wipe off the particles of dust to give the air filter a boost. Once the dust particles are removed leave it open for a few hours to dry it out.

Step four

End the inspection by cleaning the mowers’ deck. Gently remove the grass sticking to the mower deck. If the grass is dried already use the paint scraper to scrape off the unwanted grass sticking to the deck.

To sum it all up in a few lines, sputtering is caused when the lawnmower’s most important parts get neglected or kept dirty for a long time. The most common causes of sputtering are filthy carburetor, improper fuel cap, old or wrong fuel, clogged air, and fuel tank. To fix this problem without any professional help you need to know how this lawn-aiding machine works and what causes the problem.

Make it a habit to check the mower’s deck, air filter, fuel filter, carburetor, and all the critical areas before shifting it back to the garage. Use the general way of fixing the sputtering once the specific treatment is given to avoid it from happening again.

Lastly, we would like to confess here that this article is solely based on our experience. Please take professional help if the problem is not fixed with any of the above-mentioned treatments. 

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