Has your lawnmower ever stopped after starting? Well, you are not alone in this. This annoying issue happens with different types of mowers from other brands—the frequent power loss and stalling come on top of the hassles experienced by regular users.
So, if your lawn mower starts and then stops, you are at the right place. In this blog, we’ll discuss everything related to the causes of this issue. Also, we will suggest suitable fixes that provide a way out of this problem.
This problem is usually associated with different culprits, such as the wrong fuel, insufficient engine oil, clogged filters, and faulty spark plugs.
Why Does Your Lawnmower Start and Then Stop?
Table of Contents
Riding, ZT, and push mowers of different types experience a sudden power loss. It is only a bad battery issue for many domestic and professional users. So they hurry up to a nearby hardware store to get a new battery. However, proper diagnosis of the cause is more complicated than this.
You will need a thorough inspection of different mechanical parts. There are many better solutions than throwing away old parts and getting new ones. Your mower might require some cleaning.
Here we will look at the main causes behind this problem and the best remedies.
1. Low Fuel Levels
Missing out on the signs of empty fuel is easy. Your lawn mower may suddenly lose power, and you will go above and beyond to fix the problem. Still, an empty tank might not jump into your mind.
Your mower does not have a working fuel gauge. This leads to forgetting about refilling. Another reason for the urgent need for more fuel is that your fuel lines suddenly leak gasoline. We’ll get to the leak issue later on.
2. Using the Wrong Fuel
Sometimes the problem lies in the condition and quality of gasoline. Stale fuel is a common cause of frequent engine stalls. Gasoline can stay fresh for about a month. Petrol sitting in tanks or on the shelf for over a month breaks down and becomes thick.
Thick gasoline will not flow as smoothly as it should. Moreover, it will jam and clog different components of the fuel system.
3. Clogging in the Air Filter
A jammed air filter is one of the often-ignored causes of power loss in lawnmowers. A working air filter keeps a steady flow of air to the engine and, typically, the combustion chamber. Being exposed to the air from outside the machine makes the filter prone to constant clogging.
When clogged, the filter will provide an insufficient flow of air. So, gasoline won’t be able to combust correctly. Subsequently, the engine will die after it starts.
4. Clogging in the Petrol System
In a gas-powered mower, this system consists of different parts that keep the gas flowing all over the engine. The only reason this system gets clogged is stale gasoline. Thick petrol leaves behind a vicious buildup that plugs the lines and valves.
5. Clogged Gas Filter
Before reaching the engine, gasoline must pass through this filter. If it is clogged, the smooth flow of gas will be interrupted. Subsequently, the fuel mixture won’t reach the engine to combust and ignite.
6. Faulty Fuel Cap Vent
A vent in a tank’s cap allows this part to breathe. Without a vent, the gasoline will form a vacuum. Vacuum fumes will fill the tank but prevent the fuel from reaching the engine.
7. Problem in the Carburetor
In lawnmowers and tractors, a carburetor will ensure the air-fuel mixture reaches the cylinder and combusts. It adjusts the mix according to the needs of the engine. Due to the ongoing flow of petrol through it, carbon buildup is a major threat to the well-being of the entire carburetor.
Again, a dirty carburetor will affect the combustion of the fresh fuel and, eventually, the engine power.
8. Poor Oil Levels
Inadequate levels in the oil reservoir will lead to several problems in the mower body. Decreased oil in the tank increases the chances of overheating and friction. This leads to more damage and wear and tear in the internal parts.
9. Increased Oil Levels
In a two-cycle mower, oil is necessary for different functions. First of all, it lubricates engine components to reduce friction and damage. Moreover, it prevents overheating and power loss.
Emitting white smoke is one of the signs there is too much oil. If the smoky exhaust continues, the air filter will end up clogged. Other problems might occur, such as the melting of compartments and the accumulation of oil deposits.
The other task is to mix it with fuel to empower the engine. However, if the engine contains more oil, it will run rich.
10. A Dirty Spark Plug
A spark plug can malfunction due to improper cleaning or a damaged head. A dirty plug appears almost black. If you wipe it down with your thumb, it will be colored with carbon deposits.
Another concern is loose spark plug wires. Ignoring this problem will lead to spark plug failure. Lastly, a damaged or cracked plug will no longer generate any sparks.
11. A Bad Battery
The battery contributes to the ignition process in push lawnmowers and other lawn mower types. It is also essential for powering different accessories, such as lights and clutches. A battery failure makes the engine unable to turn over or start and then stop. A battery can also be unclean or missing functional wires.
12. Incorrect Choke Position
Proper setting of the choke guarantees regulating the airflow. A faulty choke won’t let you reduce the airflow when not needed. Leaving the choke plate open reduces the air and lets in more gasoline. This will make the engine shut off right after starting.
13. A Faulty Ignition Coil
The ignition coil assists the spark plug in generating a spark. It turns the battery voltage into power that turns over the engine. Sometimes, this coil collapses and short out, especially when the motor overheats. This scenario leads the lawn mower to start and then stop.
14. A Bad Cooling Fin
The cooling system inside a mower relies on the fins. These can be jammed with stubborn built-up dirt and grass clippings. This way, the fins won’t spin, and the engine won’t cool down when it overheats.
15. A Clogged Cutting Deck
Being near grass, leaves, and other lawn obstacles, a mower deck is prone to clogging and even damage. A clogged deck will not allow the mower blades to rotate and cut. This puts more pressure on the engine and makes it overworked. Eventually, the lawn mower starts and then stops due to overloading.
16. Bad Transmission
Poor transmission happens when the clutch, gears, or other hydro components are damaged or stuck. This will affect the driving experience, engine power, and uptime.
How to Fix a Lawnmower that Starts Then Stops?
Fortunately, most causes of this problem are easily detectable and cured. Many of these causes wouldn’t have happened in the first place if you regularly maintained your mower.
1. Refill the Tank
If you check the gas tank to find it is running out, refill it immediately. Make sure that the tank stays adequately filled. Also, it would be best not to always depend on the gauge, as it might get broken. It is always better to see for yourself.
While you are at it, it is better to add some fuel stabilizers. This petroleum solution minimizes gasoline evaporation while sitting inside the reservoir of gas.
2. Ensure the Fuel Quality
Bad fuel is easy to identify from its appearance. So, if you are 100%, it is the culprit; you should fully empty the fuel tank. Also, you should inspect the fuel pump, valves, and lines to remove any buildup or petrol clogs. It is essential to check the freshness of fuel before filling the tank.
3. Change the Air Filter
If you are keen on regularly cleaning the filter, you won’t find any issues with clogging. A plugged air filter can be prevented by cleaning it every 24 hours of use. But a very unclean filter must be replaced instead of wasting time and effort cleaning stubborn debris.
4. Fix the System
Different types of clogging can jam unclean fuel lines. It is not just about carbon deposits. You can find small clippings and leaves too. So, remove clogs, find damaged valves, and replace them. Remove clogged valves and apply carb cleaner to guarantee full cleaning of this system.
Generally, the best way to avoid these issues is to use fresh gasoline. If this procedure is difficult, you should consult a professional mechanic.
5. Get a New Filter
Cleaning is an appropriate action to fix a dirty air filter. However, this does not apply to the fuel filter. A clogged petrol filter should be replaced.
6. Replace the Cap
You will need a new cap in the event of a torn cap or a damaged vent. There are no fixes that may reverse the damage.
7. Clean the Carburetor
Cleaning the carburetor may seem complex for beginners, but it is easier. You do not need to disassemble the carb to clean it. You can spray it generously with a suitable carburetor cleaner until the stubborn accusations loosen.
Generally, non-chlorinated carb cleaners are better than chlorinated ones, yet none is considered eco-friendly or toxins-free. So, it is better to wear gloves and protective goggles for increased protection when cleaning the carburetor of lawnmowers.
8. Add More Oil
Incorrect oil levels can cause severe damage to the mower engine if left untreated for a long time. If you notice this issue early on, you may add more oil. However, late attention to this issue can cost you the whole engine or even a new machine.
9. Reduce the Oil
The best cure for this issue is preventing it in the first place. So, avoid overfilling the oil tank before closing the cap.
10. Get a New Spark Plug
Wait a minute before rushing to the next hardware store. It would help if you started by applying an effective plug cleaner and a wire brush to remove the buildup. As for loose wiring, you should reattach the plug correctly.
Moreover, revise the plug’s gap to avoid any unwanted shortage. Lastly, the present cracks call for immediate replacement.
11. Recharge the Battery
A dead battery may need a full charge to start kicking again. If the battery has corroded terminals, you can scrape the buildup with a knife or a wire brush. If cleaning and recharging do not work, you may get a new one.
12. Lubricate the Choke Shaft
The choke shaft might be out of shape due to gunk or debris buildup. You can clean it with a nozzle cleaner like the one on the carburetor. Then, apply some lubricant or grease to restore the choke’s smooth open and shut motion.
13. Replace the Coil
To determine the condition of this coil, you can grab an ohmmeter to test it. If the test is unsuccessful, your only option is to purchase a new coil.
14. Clean the Fins
Inspect the cooling fins and clear them of trapped dirt. Also, you can wash them and let them dry before reinstallation. In case of broken fins, you should install new ones.
15. Unclog the Mowing Deck
Turn the mower over to access the deck. Clean it and remove stuck debris. Also, check for dull blades, sharpen them, and keep them balanced before reinstalling. Replace in case of bent or damaged blades.
16. Check the Hydro Fluid
Before checking for wear and tear in the components, check the levels of the hydro fluid. Refill adequately to allow for proper lubrication of the hydro system.
Marvin is an expert in farming equipment with a strong background in agricultural engineering. He graduated from Kansas State College of Agriculture, where he received a degree in Agricultural Engineering and specialized in farm equipment design and maintenance.
