What To Do You When Your Lawn Mower Is Sputtering

What To Do You When Your Lawn Mower Is Sputtering

Is your lawnmower making a series of short explosive spitting or choking sounds? You’re not alone. A sputtering lawn mower is an issue many owners experience.

This issue is usually caused by a clogged air filter, old or bad fuel, a faulty spark plug, moisture in the fuel tank, a clogged carburetor, and so on. Sputtering may also occur when there’s poor or obstructed fuel supply into the engine. Today’s article will examine each of these causes and proffer solutions to get your lawnmower back in working order.

What happens when the lawn mower is sputtering?

The sputtering sound you hear when your lawnmower comes on is a result of inefficient combustion. This inefficiency usually indicates that the fuel in the machine is unable to combust properly due to certain factors. Sputtering gives the impression that your lawn mower wants to move, but the engine reacts sluggishly.

When you start or stop the engine, you may feel the machine vibrate intermittently. All of these symptoms are signs of a sputtering engine. Continue reading as we discuss possible reasons why your lawn mower is sputtering.

Causes of a sputtering lawn mower and how to fix them

There are several possible reasons why your lawn mower is sputtering. For this reason, it’s essential to understand the possible causes and how to fix them. That said, let’s discuss the causes of lawn mower sputtering and quick fixes.

1. Old or bad fuel

Most four-cycle lawn mowers run on regular fuel with an 87-octane rating or higher. The fuel should not contain over 10% ethanol because it can also affect performance and make the machine stutter. Sputtering can occur if you use the incorrect fuel type or if the fuel is old. Fuel has a 30-day shelf life; if it isn’t used within 30 days, the fuel may degrade. 

How to fix it: If the fuel in your machine is contaminated or old, drain it from the machine and replace it with new fuel.

2. Dirty air and fuel filters

How to fix it: If the filter is paper, replace it. However, if it is foam, wash and clean it. Wash the foam filter with liquid soap and water. Then, squeeze the filter and dry it.
An air filter ensures the air going into the carburetor is clean. However, the air filter can get clogged after a while, which can cause your engine to sputter. Once dirt clogs the air filter, it disrupts clean air flow to the combustion chamber.

3. Water Inside the Fuel Tank

How to fix it: Remove the tank cap and examine the fuel. Water is denser than fuel, so you should notice any signs of moisture. If signs of moisture are detected, drain the tank and refill with new fuel. Then, ensure the cap is securely tightened. 

Ignition moves the engine’s piston and rotates the crankshaft. This is necessary for the proper operation of the lawn mower. However, whenever water enters the fuel tank, ignition becomes difficult. So, ensure your tank cap is properly sealed. Also, verify the cap is not damaged.

4. Clogged or damaged carburetor

It’s normal for your carburetor to become clogged after a while. Fuel varnishing is a sticky residue that clogs the carburetor in your lawn mower. It is a byproduct of the deterioration of fuel that has been left in the tank for a long time. Fuel varnishing can cause your carburetor to get clogged, leading to your engine sputtering.

How to fix it: Remove the carburettor and inspect the condition. If it appears clogged, clean it with a carburettor cleaner. Ensure you focus on cleaning the carburettor’s inlet. However, if the carburettor appears defective, it’s best to replace it with a new one.

5. Clogged Mower Deck

Cutting wet grass with your mower deck will cause grass clippings to stick underneath the mower deck. If this occurs often, the grass under the deck will compact and clog the deck, leading to a sputtering engine.

Solution: First, ensure the lawn mower is switched off, then turn the mower over. Afterwards, use an object such as a brush to scrape away the grass clippings underneath the machine.

6. Dirty or faulty Spark Plug

A dirty or faulty spark plug can make starting your lawn mower challenging. It can also cause a sputtering engine. Although a dirty or faulty spark plug is not the most common cause of a sputtering engine, it could be among the factors causing your engine to sputter. In addition, the fuel filter allows gas to enter the engine. If the filter becomes clogged or blocked, the fuel flow will be interrupted, causing the engine to sputter.

How to fix it: Remove the spark plug and use a brush to clean the tip. Alternatively, you could use sandpaper to clean the plug’s terminals. If any part appears rusted or broken, replacing the faulty plug with a new plug will be the best option. On the other hand, if the fuel filter is clogged, replace it with a new one.

Essential safety precautions

Before embarking on any repairs, it is essential to adhere to certain safety tips to protect yourself. Let’s go over six safety precautions to follow before repairing your lawnmower.

1. Wear protective gear

It is crucial to protect your body parts from any danger. Protective gear like goggles protects your eyes from dust or anything that may injure them.

2. Work in a properly ventilated area

Ensure you perform your repairs in a properly ventilated area. This will ensure the fumes from the engine don’t affect your health.

3. Keep a fire extinguisher close

It is essential to ensure a fire extinguisher is close by during repairs. We’re not saying an explosion is likely when repairing a sputtering engine. However, it’s best to have an extinguisher close just in case.  Furthermore, keeping all ignition sources far away from the fuel tank is important to prevent any explosions.

4. Remove the spark plugs

Ensure you remove the spark plugs to prevent the engine from starting. This precaution will save your fingers and also prevent any risk of a fire starting.  

5. Handle the blades with care

To avoid serious injury, use extreme caution when handling the blades. Ensure you wear gloves when handling the blades and watch the sharp edges. 

6. Keep children away

Ensure there are no unsupervised children around your lawn mower. Rotating engine parts can be particularly hazardous. So, keep the machine in a secure shed and don’t allow any child to operate or repair the machine. Engine parts that rotate can be dangerous. 

Preventive maintenance tips

Prevention is always better than cure! It’s better to perform certain preventive measures to ensure your machine doesn’t sputter. After all, it is cheaper to carry out these steps than to buy a replacement for a damaged part.  Here are four measures to prevent the occurrence of a sputtering engine.

1. Use ethanol-free gas or fuel stabilizer

A fuel stabilizer helps to extend the fuel’s lifespan gas. Moreover, using a fuel stabilizer ensures the fuel remains in good condition, preventing sputtering. We also recommend using ethanol-free gas.

2. Inspect the fuel and air filters

Ensure you replace fuel filters when you notice they are clogged. This will improve gas flow to the engine and reduce the likelihood of a sputtering engine. Also, check the air filter of your lawn mower during regular maintenance and clean or replace it if necessary.

3. Regularly check the spark plug

Ensure you check your machine’s spark plug at regular intervals. Remove the spark plug and check for excess carbon buildup and signs of damage. This tip will guarantee your machine operates smoothly.

4. Fill your tank with the right type of fuel

The type of fuel you put in your fuel tank plays a major factor in your lawn mower’s operation. Ensure you fill your machine with fuel with an 87-octane rating or higher.

Final Thoughts

It goes without saying that your lawn mower should not be sputtering. Apart from the vexing noise, this issue may affect other parts of your machine. Fortunately, this issue can be quickly fixed. First, identify the culprit and perform any of the fixes we discussed above. Hopefully, you now know why your lawn mower is sputtering and possible remedies. If repairing the issue appears to be complex, we advise visiting a repairer to get the sputtering fixed. 

Frequently Asked Questions

1. What is causing my lawn mower to smoke and backfire?

Lawnmowers backfire and smoke when the engine doesn’t get enough air or receives an overly rich or lean fuel mixture. As a result, the fuel does not burn completely, resulting in smoke and sputtering. A faulty spark plug, decelerating the machine quickly, poorly adjusted or clogged carburetor, and the type of fuel used are all common causes of a lawn mower backfiring and smoking.

2. Why is my lawn mower constantly turning off?

A faulty spark plug is the most common cause of a lawn mower turning off immediately after it starts. Other causes include a clogged carburetor, dirty mower deck, blocked fuel, air filter, etc.

3. What is white smoke coming out from a lawn mower?

If you notice white smoke coming out from your lawn mower, it means there has been an oil spill, and the engine is burning oil rather than the fuel. Luckily, this is usually not a serious problem. Simply let the engine idle and wait until the white smoke clears.