What To Do If Your Lawn Mower Won't Start

1. Fuel Empty or Stale

The most prevailing cause of your lawn mower not being able to start up involves an empty or stale fuel supply. If the fuel tank is simply empty, filling it up with fresh gasoline usually solves the problem. Simultaneously, if the gasoline has been in the tank for more than one month, it can go stale and lose its ability to ignite.

This is because old fuel can be a major cause of poor performance in your engine and may even hinder the engine from starting well. To get rid of old fuel, you should drain the tank and fill it with fresh, premium-quality gasoline for the proper functioning of your engine.

2. Fuel Valve Closed

Most lawnmowers have a fuel valve that allows fuel to flow or be cut off to the inside of the engine. When this valve is off, there will be no fuel flowing to the carburetor to allow the mower to start. First, it should be ensured that the fuel valve is on before going into more complex troubleshooting.

 Such a simple and often overlooked thing, but perhaps this is the only reason your mower doesn't start. Opening the valve can allow fuel flow properly and get your mower up and running.

3. Dirty or Clogged Spark Plug

The spark plug is the most crucial thing to make your lawn mower start up, as it creates the ignition of the fuel-air mixture inside the engine. With time, these spark plugs become dirty or bad; this results in a hard time starting the mower.

Typically, it could be a faulty condition to create a spark due to carbon accumulation or rust on the plug. Check for any potential damage or dirt on the spark plug. Clean it with a wire brush if it is dirty or replace it with a new one if it is worn or damaged, to ensure the right ignition.

4. Blocked Air Filter

A blocked air filter is just choking your engine, as it prevents the proper airflow that its combustion needs. The air filter cleanses the air before mixing it with fuel. It may be blocking air passage, or perhaps the reason why an engine does not start. The solution to it is to remove it from its housing and clean it in case it is a type of foam.

In the case of paper, it goes for replacement. A clean air filter ensures your engine gets the proper mixture of air and fuel for a proper start and performance.

5. Faulty Carburetor

The carburetor is where the air mixes up with the fuel before it goes to the engine. After a while, the carburetor will clog up with debris or old fuel, and possibly have problems starting. If you feel the carburetor is the issue, you will have to remove the air filter to reach it and spray some carburetor cleaner down into the throat of the carburetor.

Allow this cleaner to sit for a few minutes to dissolve any kind of buildup. If it starts but is running rough, you may need a more thorough cleaning or even may have to have a professional service it.

6. Bad Battery (on Electric Start Mowers)

Another very important reason an engine may fail to start in an electric lawn mower is a dead or weak battery. First, check the charge on your battery. Low levels of charge must be recharged with the proper charger.

The terminals also need to be checked for corrosive buildups or loose connections. Clean the affected area with a mixture of baking soda and water and tighten the terminals. For the electric start system to work, the battery has to be full and properly connected.

7. Low Oil Levels

Most modern lawnmowers are designed to make sure the engine does not start when the oil level is too low. This prevents further damage to your engine in the event of low lubrication. Check the oil level by finding the dipstick and pulling it out. Clean it.

Put it in and pull it back out to check the level. If low, fill with the right type of oil until the level is within the normal range. Do not overfill, because too much oil will also cause issues.

8. Safety Features Not Engaged

Lawnmowers have several safety features designed to prevent the possibility of an accidental start. Most require a person to hold down a safety bar or lever of some kind in conjunction with starting the engine. Should these be missing, the mower will not turn on.

Ensure you start it again using the proper procedure, including the proper throttle or choke setting to ensure all safety features are on and working as they should.

9. Clogged Mower Blade

Another probable reason for an engine not to start or stall is a clogged mower blade with built-up debris or clippings of grass. Inspect the blade after ensuring that the mower has been turned off and the wire attached to the spark plug has been disconnected for safety.

Carefully lean the mower on its side to carefully clear accumulated grass, leaves, or debris from around the blade and mower deck area. Check the actual blade for any damage or over-wear. Clearing blockages and sharpening the blade can do much to make the mower start and run well.

10. Fuel Line Issue

The fuel line is responsible for conducting gasoline from the tank to the engine. Any crack, leak, or blockage in the fuel line breaks the flow, resulting in difficulties while starting. Inspect the fuel line for cracking or pinholes from one end to the other.

If you find something, you will need to replace that part of the fuel line because the fuel line must be intact so that there will be proper delivery of fuel to the carburetor.

11. Clogged Fuel Filter

A clogged fuel filter restricts the flow of gasoline into the engine, causing difficulty while starting. It filters out debris and contaminants from the fuel; this filter itself may become clogged over time. If this seems like the problem area for you, then you need to check if the fuel filter is clogged.

After all, one desires a continuous flow of fuel to the very engine that is the heart of your mower. Changing the fuel filter from time to time can save one from starting problems and keep the mower running without glitches.

12. Starter Mechanism Issues

In some instances, such an effect might be created on the engine in case of certain problems with the starter mechanism or pull cord, thus not allowing it to turn over. If the pull cord is very hard to pull or does not properly engage, there might be a problem with the starter mechanism.

Check the pull cord and the starter assembly for any evidence of damage or misalignment. If necessary, check your mower's manual or get professional help to repair or replace the starter mechanism. What you want to help get your mower running is a good working starter mechanism.

13. Engine Overheating

If in fact, the engine has overheated, it will have internal damage or be seized and not start. Overheating can occur when the mower has been used excessively without the correct oil or simply running too long. If you suspect overheating has occurred, let the engine completely cool before attempting to restart it.

Check the level of the oil and make sure that it is adequate. If, after this, it still does not start, internal damage could be present, in which case you will have to call a professional to get it repaired.

First things first, take a look at your fuel tank. Is it full of gas? Fill it up if that is not the case! Hold on make sure the gasoline is fresh. Old more than 30 days may become stale making it hard for your mower to fire up.

If your gas smells funny, or it has been sitting in there a while, drain the tank and replace the fuel in it with fresh fuel. Also, check to see if your mower has a fuel valve and make sure it is turned on. 

First, the spark plug should be found. It is usually on the front or sideways of the engine. One should unplug the spark plug wire and take out the plug with a special socket spark plug socket.

Inspect the plug for any signs of damage, corrosion, or buildup. If the plug is dirty, clean it using a wire brush. In case it shows wear or damage, replace it with a new one. Replace the spark plug and reconnect the wire once you are done.

The air filter covers the entry of any form of dirty or unwanted debris into the engine. Locate the air filter cover first; this is usually along the side of the engine. Remove the filter. Now, take out the air filter.

Check it for dirt or clog-ups. It can either be dirty or clogged, in which case it would constrict the flow of air towards the engine. Thus, it may not start or run very poorly. Now, if it's a dirty filter, just clean it using the instructions from the manufacturer. Replace it if it is beyond cleaning. 

Priming the engine can force fuel into a cold carburetor, assuming the engine has been standing for some time. If your mower is fitted with a primer bulb, press it several times 3 to 5 presses before trying to start the engine.

That pushes fuel into the carburetor, giving it a better chance of firing up. Sometimes, after depressing the primer bulb, it will take a few seconds for the fuel to settle before the mower will crank

The carburetor correctly mixes fuel and air for combustion. If your engine is not starting, it could be due to a clogged-up carburetor. Reach the carburetor by removing the air filter. Spray carburetor cleaner into the throat of the carburetor and let the cleaner dissolve the blockage or trash inside.

Let it sit for a few minutes, then try to start the mower. If it starts but then runs poorly, this would be indicative that more serious cleaning or professional servicing of the carburetor may be in order.

The fuel line carries fuel from the tank up to the engine. After that, it needs to be carefully checked for cracks, leaks, or any sort of damage. A spoiled fuel line can not carry the fuel up to the engine due to starting problems and bad performance by the engine.

This would result because of not having appropriate amounts of fuel at the appropriate time. In case of any damage, replace the fuel line to keep the fuel supply continuous to the engine.

Low oil levels can activate safety mechanisms in a way that the mower will not start to some extent of protection against engine damage. To check the oil level, locate the oil dipstick, which is generally located at the bottom of the engine. Pull it out and clean it with a cloth.

Reinsert the dipstick completely, then pull it out once again and read your oil level. If it is low, that is, below the "Full" mark, then the right kind of oil should be added to it. Overfilling of the oil must be avoided. 

Most modern lawnmowers are designed with several safety features that must be engaged for the mower to start. Most of them have a safety bar that must be depressed while pulling the starting cord. Not having this down far enough and the mower will not begin to start.

Next, ensure the throttle or choke lever is moved to a start position. Most engines start on a throttle position set to "start" or "choke." There are some common pitfalls in mower maintenance overlooking these settings is one of them double-check your settings before trying to start an engine.

An obstruction within a mower blade due to junk or even grass gathering can have an impact on the engine's potential to either stall or completely fail to start. Before inspecting the blade, turn the mower off and pull the spark plug wire out to avoid any kind of accidental starts.

Carefully tip the mower on its side with the air filter facing up to prevent flooding, then check the area around the blade. Grass, leaves, and other debris may be wrapped around the blade or under the mower deck; remove these. Inspect the blade, too, for any damage or excessive wear. 

It is also extremely very important to mowers that have an electric start feature. To begin with, the charge on a battery should be checked. A dead or low battery should be recharged using an appropriate charger. Unless the battery holds a charge, it may need replacement.

Besides, the terminals should be checked for any corrosion or loose connection. Clean corrosion off with a mixture of baking soda and water. Also, if the terminals are loose, they need to be tightened. You want the connection between the battery and the mower to be good for it to start.

With self-propelled mowers, sometimes the drive system creates some resistance in and of itself. Try disengaging the drive mechanism and manually push the mower. This reduces the resistance and often allows easy start-up. You can then re-engage the drive system and continue the mowing once it's up and running.

If you have worked your way through all of the above troubleshooting steps and your mower still will not start, then it is time to break out the owner's manual. Many model-specific troubleshooting can be found within the manual that might walk you through complex issues.

It may also contain information about regular maintenance schedules, replacement parts, and warranty coverage. Having your manual with you while you're troubleshooting can save you so much time and help you narrow down problems you wouldn't have thought of.

If all else fails, and your mower refuses to start, it may be time to call in the experts. A professional can find and fix the more serious problems that could be beyond your capability to repair. Expert help will also be able to get your mower running once again, from rebuilding a carburetor or an internal engine problem to electrical issues.

While it will be a little bit more expensive than trying to fix it yourself, professional repair can give your mower a long life and help it avoid some breakdowns in the future.

Some of the common starting issues with lawnmowers can be identified and resolved by using some of the fundamental/basic equipment and consumables listed below;

• Gasoline: Fresh and of good quality to replace any stale or old fuel within the fuel tank.
• Fuel Stabilizer: Use a fuel stabilizer where you will lay the gas for some time; therefore, in any further case, stale fuel will not cause an obstacle
• Screwdriver Set: You would need these screwdrivers to remove screws from certain items such as the air filter cover or carburetor.
• Spark Plug Wrench: A special tool used to pull out and set spark plugs.
• Spark Plug Gap Tool: To check and set the gap on the spark plug, in case that is what is needed.
• Air Filter: New filters if the old one is blocked or broken.
• Carburetor Cleaner: This will be used to clean up the carburetor from a probable build-up of gummed-up substances.
• Oil: The correct type of oil to top up, if that is what is needed.
• Oil Filter Wrench: This should be used if your mower has an oil filter that needs replacement.
• Pliers: These are handy for the detachment and attachment of parts of a mower, like the fuel line or clips.
• Battery Charger: For electric start mowers that may run a little low.
• Clean Rags: Use these to wipe down dirt and debris off various parts and to check the oil levels of the mower.
• Safety Goggles and Gloves: To ensure safety while working on your mower.
• Owner's Manual: For model-specific instructions and troubleshooting information.