Why did my lawnmower stop working while I was mowing? It’s a common question no gardener wants to ask when they have half a cut lawn. Most often, a mower running will be reliable, yet it can be a nightmare when a lawnmower won’t start.
There are several reasons and a few causes why small engines on mowers decide to stop once they have been running for a while. You can find the lawnmower won’t start because of fuel, air filters, or an issue with the carburetor.
Luckily, when lawnmowers don’t turn over, it isn’t the end of the world. In our guide, you can learn why a Briggs and Stratton lawn mower won’t start. By the end, you’ll know all the quick fixes to get the mower started so you can finish cutting the rest of your grass. (Read Can You Apply Crabgrass Preventer Too Early)
Common Problems Why Mower Won’t Start
We must understand how to start and operate a mower before we can fix the issues. The mower begins and gets ready to run when we turn on the power and turn the ignition key. A riding mower doesn’t start until we get on it. It connects the electrical cables by activating the safety switch while seated.
As a result, the battery can supply power to our lawnmowers. It is a continual process, and the safety disconnects us when we get up from the lawn mower chair. The lawn mower’s engine cuts off because of losing contact with the power source.
The battery controls the spark plugs to burn fuel in the cylinder. Here, a small explosion pushes the pistons to turn the mower engine. Now, with a basic overview, you can begin troubleshooting your problems. Before you drag the mower in for repairs or invest in replacing costly parts, there are many things to check that can save you time and money.
Here, you can see why and how to deal with a clogged air filter, dirty or lousy plug, faulty safety cable, or you have a clogged mowing deck. You can even find old fuel has blocked your fuel filter.
Here are a few steps to determine why the lawn mower won’t start.
1. Lawn Mower Air Filter
Your lawn mower’s air filter shields the engine and carburetor from debris like grass clippings. The engine won’t run or start if the filter is clogged. To fix this, change your dirty paper filters, or if you have foam filters, you can wash these to remove the dirt.
To avoid these issues, you can clean or replace foam filters after 25 hours of engine use.
Removing filters from the air intake differs according to your mower type:
- Pull the spark plug wire from the plug on a walk-behind mower
- On your riding mower, shut off the engine and apply the parking brake. After that, remove the filter’s housing.
For paper filters, there is just one option: replacement. Wash a foam filter in hot water and detergent to remove dirt. After letting it dry, add the recommended oil to your filter and reinstall it so your engine can run efficiently.
2. Bad Spark Plug
The spark plug, which produces the spark that ignites the fuel in the engine, might be to blame. The spark plug may be the root of your machine’s problems if it’s detached, loosened, or covered with water or carbon buildup. One symptom is seeing black smoke once your mower starts.
Find the spark plug, which is frequently on the mower’s front, and unplug the wire to expose the plug by doing so. The spark plug can be removed by unscrewing it with a socket wrench.
Examine the insulator and electrode. Spray brake cleaner or carb cleaner onto the plug. Let it sit for a few minutes before wiping it with a clean towel. The spark plug should be reinstalled by hand and then with a socket wrench for the last tightening. If the issue continues, consider switching the spark plug and getting a new one.
A new plug can make all the difference on your lawn mower, yet a new plug can quickly suffer if the issue is something else. (Learn How To Get Rid Of Sticker Weeds)
3. Mower Deck Debris
The mower’s deck makes a place for grass clippings to gather while preventing them from falling. When mowing a wet lawn, grass clippings can jam the mower deck and stop the blade from moving. If these are there, it can destroy your mower running and will be one way to ensure your mower won’t start.
If the starter rope is stuck or hard to pull, the deck is a probable cause. Ensure your lawn mower is off and the plug wire is disconnected. Turn the mower on its side to look underneath.
Use a trowel to scrape the grass clippings from being stuck between the blade and the deck. Once clean, upright your mower, connect the plug and start your lawn mower.
4. Gas Tank Problems
An empty gas tank is the most apparent cause of your push mower breaking down. Your mower won’t operate if your fuel level is too low.
Fix: Add fresh fuel to your mower fuel tank.
5. Bad Fuel in Mower
Gas sitting in your fuel tank for a while may gum up and clog the fuel system in your mower.
Most unleaded gasoline contains ethanol. After around 30 days, the gasoline mixture degrades and loses some of its effectiveness.
The ethanol that is added to gasoline pulls moisture out of the atmosphere. A sticky substance builds up, and your mower won’t start as the fuel will stop flowing as this ethanol and moisture mixture dissipates.
Gasoline has a short shelf life, so follow these tips to get the best fuel results:
- Use fuel within 30 days and from a busy gas station
- Don’t leave gas outdoors
- Store gas in a dry place
- Drain your gas tank and add fresh gas and a fuel stabilizer to stabilize and clean the mower fuel system and fuel filter inlet.
6. Wrong Fuel in Your Mower
It’s important to know what to look for when buying gasoline because so many different fuels are available today. To find out what is in your gasoline, read the label on the fuel tank. Push mowers use empty petrol with a minimum octane rating of 87 and a maximum ethanol percentage of 10%.
Regular or E10 gasoline is the most common label for this kind of fuel. To choose the proper gasoline, don’t forget to read the label. It’s important to remember that most mowers today have 4-stroke or 4-cycle engines and run on unleaded fuel.
Your push mower can have a 2-stroke or 2-cycle engine if it is older. Gasoline and oil must be mixed to fuel this type of engine.
Consult your owner’s manual for information on the proper gasoline-to-oil fuel mix ratio. You may need to know the serial number or part number if there are many engine variants. (Read Best Topsoil For St Augustine Grass)
7. Dirty Carburetor
Because of gumminess, the proper amount of gas and air required to prevent combustion in the engine’s cylinder may not be allowed by a dirty carburetor. When the engine can no longer get the fuel and oxygen it needs, your mower may run slowly and stop.
Cleaning your carburetor will help eliminate any remaining crusty buildups and gooey deposits from using ethanol-containing fuels and old fuels. This tutorial includes directions for cleaning the carburetor on a push mower. You may need to rebuild or replace your carburetor if it is too dusty or has damaged parts.
8. Bad Fuel Pump
Your lawn mower may have a fuel pump. A fuel pump is needed when the carburetor is above the gas tank. Wrong fuel pumps leak or are fractured; your pump may not pump fuel if not sealed.
Sometimes, the lawn mower fuel pump is the issue. Make sure fuel is reaching the fuel pump inlet. Remove the fuel pipe from your carburetor, start your mower, and check for constant or pulsating fuel flow. If you’re not getting fuel, it’s probably your fuel pump.
9. Fuel Filter
Some lawnmowers include an inline fuel filter. This small fuel line filter might clog with a lack of flow. This stops your engine from getting fuel to the carburetor. Thus, you can’t mow your grass.
10. Blocked Fuel Lines
Your mower dies when it’s out of fuel, which happens with clogged fuel lines. When the pipes get clogged, you must remove the block so energy can reach the carburetor.
You can use fuel clamps to start and stop fuel to find the fuel line obstruction. To unclog the fuel line, remove the spring, ay it with carburetor cleaner, and use compressed air to clear the line.
11. Mower Fuel Cap
There is a vent in the gas cap of a push mower that lets air pass through the lid. Your fuel tank behaves like a vacuum and keeps the gas fumes inside when this vent is blocked, preventing fuel from flowing out of the tank to your carburetor, and the mower dies.
Removing the fuel cap and seeing if the vehicle starts may help you identify a bad gas cap. If it functions appropriately, replace your lid and keep it running. You’ll need a new gas cap if your lawn mower stops working.
12. Bad Ignition Coil
If the ignition coil is defective, your lawn mower may stop working once it gets heated. The coil’s windings separate and short out. This prevents the spark plugs from receiving the voltage for proper operation.
Use an ohm meter to look for continuity issues to spot a faulty ignition coil. Replace the lock if it won’t create a spark in your spark plug.
13. Dull Blade
When using a lawn mower with a clogged mower deck, the motor has to work harder to turn the mower blade through the accumulation of trash beneath the deck.
Worn-out mower blades might make your engine work harder. This could lead to engine overheating, which would cause your mower to die while working.
Sharpen your mower blade and scrape out trash from your mower deck. (Learn How To Plant Centipede Grass Seed)
The mower died while mowing and won’t start for several reasons. We have covered the significant causes of this. Most are quick fixes and easy to remedy, although you must ensure you are on a hard surface with your lawn mower to be safe.
Changing a dirty air filter or getting fuel flowing to your carburetor is something you can do without calling in the professionals.