12 Causes of a Rough and Stuttering Push Mower: How to Repair
The car’s engine is sputtering and not performing as well as it once did. Your push lawnmower’s efficiency will suffer as a result.
If your lawnmower’s engine is sputtering or running roughly, you should start by eliminating any potential sources of obstructing air, fuel, or spark as the cause. The next step is to seek for potential engine-stressing objects.
Some causes of a rough run in a push mower include:
- Used fuel
- Air filter obstruction
- Congested choking
- Caused by a clogged fuel line
- The Fuel Filter is Clogged
- Unclean carburetor
- Broken gas cap
- Dull spark plug due to grime buildup
- quickness on the ground
- Damaged throttle cable
- Mower deck obstruction
- Deflated mowing tools
Ensure the engine has cooled and all moving parts have stopped before doing any maintenance on the lawnmower. The spark plug(s) must be removed from the spark plug boot(s) before any maintenance may be done, and all other safety measures should be taken as described in the push mower’s user guide.
There could be affiliate links in this post. In some cases, we may receive a commission for purchases made through these links. Because we are an Amazon Associates program, we receive a small commission on some of your transactions.
Prior to diagnosing, repairing, or operating the equipment, be sure you’ve read and understood all of the safety instructions that came with it.
If you are unsure of how to proceed, lack the necessary expertise, or are unable to execute the repair properly, you should seek the advice of a professional.
Table of Contents
This Is Why Your Push Lawnmower Stutters and Runs Rough
Push Mower with a Clogged Air Filter
The air filter is supposed to keep dirt and debris out of the engine’s air supply, but it can also be the culprit if the engine isn’t getting enough air.
If the air filter isn’t regularly cleaned or replaced, it might become clogged with debris like grass clippings, dirt, and dust.
As a result, the engine may start to run roughly or even overheat and start to smoke.
The air filter should be changed once a year and cleaned numerous times during the mowing season.
If you use your push mower in very dusty conditions, or if you mow more frequently than the average homeowner, the filter may need more frequent cleaning or replacement.
Don’t EVER try to use your push mower without the air filter. If dirt and debris get inside the engine, it could malfunction and even break down.
It’s a good idea to inspect the air filter and clean it if it’s even slightly soiled. A new air filter should be installed if the old one is too dusty, too broken, or is no longer able to properly seal off the air intake. Please use these steps to clean your air filter.
Cleanse a push mower paper air filter:
- Take off the air filter from its housing.
- Clean the housing by wiping down the inside and exterior. Don’t let any grime get into the machine’s air filter.
- Lightly tap the filter on a hard surface. You want to shake the filter so that as much dirt as possible falls out.
- Ensure that light can still pass through the paper element of your air filter by holding it up to a light. If the air filter hasn’t been damaged, you can keep using it. You should get a new one if you can’t fix it.
- Put back the air filter and cover the housing.
- Foam pre-filters can be cleaned using a solution of mild detergent and water, if your air purifier has one. Do a quick rinse and dry naturally. The pre-filter should NOT BE oiled in any way.
Cleanse a push mower foam air filter:
- Take off the air filter from its housing.
- Clean the housing by wiping down the inside and exterior. Don’t let any grime get into the machine’s air filter.
- Remove grime from the filter by washing it in a solution of mild soap and water.
- Be sure to give it a good rinse to get rid of the soap. Take the filter apart, drain the water, and lay it flat to dry.
- It is recommended to use filter oil or engine oil to grease the filter after it has dried. Get it wet so that oil is evenly distributed throughout, but not so much that it drips. Remove any extra oil from the filter by squeezing it.
- There should be little doubt that you will need to change the foam filter if you see any black areas or tears in it.
- Put the air filter back in place.
Push Mower Choke Is Stuck Or Set To The Incorrect Position
While starting a cold engine, the choke is utilized to reduce the volume of air combusted along with the gas. More fuel and less air means the mixture can run richer.
If you want to keep your engine running after it has started and warmed up, you’ll need to move the choke lever to the “off” position.
The engine on a push mower might sputter and bog down if the choke is in the wrong position or gets jammed open or closed.
An automated choke is used in some push mowers. You can get help with these types of issues by contacting a local lawn mower dealer.
When starting the engine from cold, make sure the choke lever is closed; when starting from warm, make sure the lever is open.
If the airflow isn’t working properly even after adjusting the choke lever, make sure the plate is opening and closing.
For a blocked choke, try a carburetor cleaner, and if the cable is worn or broken, get a new one.
Tired Gas in a Push Mower
After around 30 days, gas loses its quality and should be replaced. The fuel system and engine are negatively impacted by the ethanol used in most gasoline today.
This alternative fuel has a high osmotic pull, meaning it draws moisture from the air and into the fuel system. Unlike liquids, gases cannot be dissolved in water. It’s highly corrosive, leaving a varnish residue, and causes fuel limits and component problems.
The engine’s performance will suffer as a result of the fuel limits imposed.
REMEDY: Drain and replace the petrol in the tank. You may minimize the buildup of residue and moisture in the fuel system by replacing the old gas with new fuel and using a fuel system cleaning and stabilizer, such as Sea Foam Motor Treatment.
Mowers with 2-cycle and 4-cycle engines have distinct fuel preferences.
- In order to power 2-cycle engines, a combination of gasoline and oil is required. Blend air-cooled 2-cycle engine oil with unleaded gas that has an octane rating of at least 87 and no more than 10% ethanol.
- For a breakdown of how much fuel goes into what for the most popular push mowers, read this article.
- For 4-cycle engines, regular gasoline with no additives and no more than 10% ethanol is recommended. These engines will feature dual oil and fuel fills. That two things should not be combined.
Gasoline Line Blockage in a Push Mower
Accumulated deposits in the fuel system may cause fuel flow restrictions when they become stuck in the fuel line.
With the gasoline shut-off valve or hose crimp pliers, you can temporarily halt fuel flow while you inspect the flow coming out of a line, helping you locate a clog.
Take the tube away from the gas tank. When you’re checking the fuel flow, catch any excess in a container. The fuel tank must be lower than the storage container. There must be a gasoline pump in place for the fuel to flow upward.
Turn on the fuel and observe it filling the container through the fuel line.
If the fuel is not flowing properly, try disconnecting the fuel line from the mower. Try spraying carburetor cleaning into the pipe to see if you can get the clog to loosen up.
Next, try to dislodge the obstruction by blasting the line with compressed air. Carburetor cleaning and compressed air should be used repeatedly until the clog is removed.
If you are unable to remove the fuel restriction or if you notice breaks in the fuel line, you will need to replace it with one of the same length and diameter.
Push Mower with a Clogged Fuel Filter
The mower’s engine and fuel system are protected from debris and other potential problems by an inline fuel filter. The fuel filter, like the air filter, needs to be regularly replaced to ensure clean fuel.
Due to dirt buildup, the gasoline filter might become clogged, preventing fuel from flowing freely. Without enough fuel, the carburetor could clog and the engine could sputter.
The fuel filter should be changed once a year, or more often if it gets clogged or broken.
THE SOLUTION: Swap out the old, clogged filter with a brand new in-line model. Make sure the arrow on the replacement filter is pointing in the direction of fuel flow by inspecting the filter before installation.
Scratched Deck from Push Mower
The carburetor combines the fuel and air for the engine’s combustion process. Inadequate fuel-air mixture is one cause of engine shakiness when the carburetor isn’t doing its job.
To determine if a defective carburetor on a push mower is to blame for a lack of fuel, the fuel supply must be checked. If you aren’t, perhaps your gasoline line or fuel filter is clogged.
The next step is to take out the air filter from its housing. To clean the carburetor, simply spray it with the cleaner. It’s time to get the car going.
The engine probably needs to be carburetor cleaned if it runs well before the cleaner is burned in the engine and then starts running slowly again.
The solution is to clean the carburetor in the same way you would clean the one on a lawn mower that you push.
Having a defective gas cap on your manual lawn mower ranks as our seventh most common lawn care issue.
Gas caps are perforated to let air into the tank and prevent fuel from leaking out. Since air can’t enter the tank when the gas cap is broken, the tank will eventually go into vacuum when fuel is used up.
There won’t be enough suction to let the petrol escape the tank. Using a pressure gauge, check the vacuum in the tank if you have a mower that is not running smoothly.
If the gas cap vent on your gasoline tank is blocked, here’s what to do about it:
- When the engine is stuttering, you can improve its performance by letting air into the tank by loosening the fuel cap. If the engine improves in performance right away, it could be due to a faulty gas cap that is not allowing exhaust gases to escape.
- Verify the issue by letting the mower run while making sure the gas cap is securely fastened. When it slows down, have a listen with the cap off. If it runs smoother once you loosen the gas cap, that’s further evidence that it was the gas cap all along.
Get a new gas cap for your push mower and put it in.
Push Mower with a Grimy Spark Plug
It’s possible that a spark plug that’s been fouled is the cause of the engine’s harsh and sputtering performance. Spark can also be affected by factors such as spark plug wires that are slack or the electrode gap on the plug itself.
The spark plug has to be taken out and looked at. If it’s really dark, has a burnt electrode, or is otherwise damaged, it should be swapped out for a new one. If it is in good shape and only slightly unclean, a wire brush should be sufficient to remove the buildup.
You should check the spark plug gap according to the engine manual. After any necessary repairs are done, the spark plug wire should be reattached securely.
To fast for a Push Mower to Cover the Ground
Mowing speeds are conditional and depend on things like grass height and wind. It’s important to mow more slowly on a lawn with thick, tall, or damp grass than on one without these characteristics.
When mowing, if the ground speed is excessively high in comparison to the mowing circumstances, it might place unnecessary stress on the engine and cause it to stall. And the quality of the cut you get from a manual mower will suffer as a result.
Determine how fast you need to mow the grass, given the current weather and lighting circumstances. When you notice that your car’s engine is losing power, it’s time to slow down.
For optimal results, mow tall grass in more than one pass. Even while it will take much longer, you will get cleaner cuts and won’t have to worry about the motor burning out.
To accomplish this, raise the cutting height of your mower for the initial cut and then lower it for subsequent cuts.
The Push Mower’s Engine Is Going Too Slowly
Powering a push mower and mowing deck requires a sizable engine. If the mower starts to run roughly after you engage the blades, try increasing the engine speed.
Depending on the model, your push mower may include a throttle lever or variable speeds. To get the best mowing results, set the throttle lever to its highest position and the speed to the appropriate level for the terrain.
Please be aware that some push mowers have an automated throttle and require no modifications. You can get help with these types of issues by contacting a local lawn mower dealer.
FIX: Raise the accelerator pedal to its highest setting.
Push Mower with a Clogged Deck
If the mower’s deck gets clogged with dead grass and other debris, the engine will have to work harder to operate the blade.
The engine will struggle to turn the blade through all of this extra weight, and as a result, performance will suffer.
For a solution, try using a deck scraper or wire brush to regularly clean the mower deck. Don’t attempt to trim wet grass. This type of grass is more likely to form clumps and stay adhered to the patio.
If you want to prevent debris from clinging to the deck, you might try using a deck spray. As useful as it is, it is not a foolproof method of preventing grass from ever again attaching to your deck.
Faulty Push Lawnmower with Dull Blades
One of the keys to a clean cut is a razor-sharp mower blade. If your mower blade is dull, you could be tearing the grass and leaving brown tips just a few days after you mow.
The problem of a blocked lawn mower deck is exacerbated by dull mower blades, which can also lead to a bad cut appearance. To make matters worse, it takes more power from the engine to spin dull blades through a deck full of grass, so this will just slow the mower down further.
Resolved: Take the mower blade off the deck. Get that knife in tip-top shape by sharpening and balancing it.
Still Experiencing Issues with Your Push Mower?
Throughout the course of a push mower’s lifetime, its owner is likely to run across a number of recurring issues. Even if you buy a top-of-the-line mower, it will eventually break down.
As such, I compiled this tutorial to assist you in determining what’s causing these issues and how to correct them. Issues with Push Mowers and How to Fix Them
