Common lawn mower issues. Lawnmower Won’t Start? Do this

Troubleshooting Lawn Mower Starting Problems

The air is warmer and the grass is growing – time to break out the lawn mower. Unlike your car, your lawn mower and other lawn and garden equipment are not used regularly and the time spent sitting in storage can lead to problems with them running properly.

When you take your mower out for the first time, you may encounter a variety of situations. If you are lucky, the lawn mower will start with the first pull of the cord. Unfortunately, after months of sitting around, it is likely your lawn mower may not run smoothly, or even start at all. Before you give up, here are some things you can do to troubleshoot the problem.

Causes of engine trouble

If your engine starts but does not run smoothly or doesn’t start, the culprit could be air intake or fuel system related. The problem could be the age of the fuel in the tank, dirt or debris in the carburetor or an obstructed fuel tank vent. Other causes could be a fouled spark plug or a dirty or clogged fuel filter that restricts the amount of fuel getting to the carburetor.

Change the gasoline

If this is the first time you have tried to start the engine since last fall, fresh fuel may be in order. Gasoline will go bad in as few as 30 days, especially when fuel is mixed with ethanol as it is in many areas. Ethanol attracts moisture and over time the moisture will dilute the gas.

If the fuel is old, it should be dumped into a container for proper disposal and fresh fuel should be added. Fuel additives are readily available wherever auto parts are sold and may be helpful in not only starting your engine, but also in cleaning out any gum or varnish deposits in your carburetor while the engine is running.

After adding new fuel, check the gas cap. In many small engines, the gas cap also has a vent that serves as the fuel tank ventilation. In order to work properly and supply a sufficient amount of fuel to the carburetor, the vent must be open and free of any debris.

Check the air filter

The job of the air filter is to remove dirt and debris from the air before it enters your engine. The filter may become clogged and not allow a sufficient amount of air into the engine for it to run smoothly. If the filter is dirty, it should be replaced.

Examine the spark plug

A dirty or fouled spark plug can cause your lawn mower to not start. It can also work itself loose, causing issues. If the spark plug appears to be seated correctly but the engine doesn’t start, a new one may be in order. For a few dollars, this easy fix can get your small engine working again. Be sure to use the correct replacement spark plug designed for your lawn mower.

Check the oil

Check the amount, color and consistency of the oil. If it appears dark black, change it. If the oil level is low, add the proper oil, identified by your owner’s manual, to the engine – but be careful not to overfill it!

Look at the Fuel Filter

The fuel filter keeps dirt and contaminants in the fuel from getting into the carburetor. If it becomes clogged, it can prevent a sufficient amount of fuel from passing into the combustion chamber, preventing your engine from starting. Check the fuel filter, replace it if it is dirty or clogged.

I’m still having issues with my mower – what should I do?

If you are still having problems, it might be time to take it to a small engine repair shop to have a mechanic look at it. With their expertise, they’ll get to the bottom of the problem in no time.

Learn more about Champion parts, find your car part, or find where to buy your auto part today.

The content contained in this article is for entertainment and informational purposes only and should not be used in lieu of seeking professional advice from a certified technician or mechanic. We encourage you to consult with a certified technician or mechanic if you have specific questions or concerns relating to any of the topics covered herein. Under no circumstances will we be liable for any loss or damage caused by your reliance on any content.

Lawnmower Won’t Start? Do this.

Bad gas or a dirty carburetor are the most common reasons for a lawnmower that starts hard or runs rough.

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A lawnmower that won’t start, especially when taken from storage, is almost always due to one problem: bad gas.

Storing a lawnmower in the fall without adding gasoline stabilizer to the fuel tank can cause the fuel to break down and plug the fuel passages. If fixing that problem doesn’t help, there are a few others that can help fix a lawnmower that won’t start, as we explain here.

How to Fix a Lawnmower That Won’t Start

Replace the Bad Gas

Over time (like the six months your lawnmower sat in your garage over the winter), the lighter hydrocarbons in gas can evaporate. This process creates gums and varnish that dirty the carburetor, plug fuel passages and prevent gas from flowing into the combustion chamber.

The carburetor bowl below formed corrosion and deposits during storage, which can easily plug fuel passages and prevent the engine from starting.

Storing equipment without stabilizing the gas can lead to deposits that foul the carburetor or injectors.

Ethanol-containing gas can absorb water from the atmosphere, which can lead to phase separation, which occurs when ethanol and gas separate, much like oil and water. Ethanol that has absorbed enough moisture and has sat long enough can foul the fuel system and prevent the engine from starting.

No matter how many times you yank the pull cord and pollute the air with your advanced vocabulary, the lawnmower won’t start if it’s trying to run on bad gas.

In extreme cases, evaporation of lighter hydrocarbons can change the gasoline’s composition enough to prevent it from igniting. The gas may be fueling the engine, but it doesn’t matter if it won’t ignite.

Bad Gas in Your Lawnmower? Here’s How to Fix It

If you neglected to add gasoline stabilizer to the fuel prior to storage, empty the tank and replace with fresh gas. If the tank is nearly empty, simply topping off with fresh gas is often enough to get it started.

On some mowers, you can easily remove and empty the fuel tank. Sometimes that’s more trouble than it’s worth. In these cases, use a fluid extraction pump or even a turkey baster to remove the bad gas. You don’t need to remove all of it; but try to get as much out as possible.

Clean the Carburetor

You’ve replaced the fuel, but your lawnmower still won’t start.

Next, try cleaning the carburetor. Remove the air filter and spray carburetor cleaner into the intake. Let it sit for several minutes to help loosen and dissolve varnish and gums.

Remove the air filter and spray carburetor cleaner into the intake. Let it sit a few minutes to loosen deposits.

On some carburetors, you can easily remove the float bowl. If equipped, first remove the small drain plug and drain the gas from the bowl. Remove the float bowl cover and spray the float and narrow fuel passages with carburetor cleaner.

This kind of “quick-and-dirty” carburetor cleaning is usually all it takes to get the gas flowing again and your lawnmower back to cutting grass.

If not, consider removing the carburetor from the engine, disassembling it and giving it a good cleaning. Be forewarned, however: taking apart a carburetor can lead to nothing but frustration for the uninitiated. Take pictures with your phone to aid in reassembly. Note the positions of any linkages or the settings of any mixture screws, if equipped. If you’re at all reluctant, visit the servicing dealer instead.

Consider replacing the carburetor altogether. It’s a fairly simple process on most smaller mowers and it’s often less expensive than taking it to the dealer.

Direct compressed air from the inside of the air filter out to remove debris that may be reducing airflow and preventing the lawnmower from starting.

Clean/Replace the Air Filter

With the air filter removed, now’s the perfect time to clean it.

Tap rigid filters on a workbench or the palm of your hand to dislodge grass clippings, leaves and other debris. Direct compressed air from the inside of the filter out to avoid lodging debris deeper into the media.

Use soap and water to wash foam filters. If it’s been a few years, simply replace the filter; they’re inexpensive and mark the only line of defense against wear-causing debris entering your engine and wearing the cylinder and piston rings.

An incorrectly gapped spark plug can prevent the engine from starting. Set the gap to the specification given in the owner’s manual.

Check the Spark Plug

A dirty or bad spark plug may also be to blame. Remove the plug and inspect condition. A spark plug in a properly running four-stroke engine should last for years and never appear oily or burned. If so, replace it.

Use a spark-plug tester to check for spark. If you don’t have one, clip the spark-plug boot onto the plug, hold the plug against the metal cylinder head and slowly pull the starter cord. You should see a strong, blue spark. It helps to test the plug in a darkened garage. Replace the plug if you don’t see a spark or it appears weak.

While you’re at it, check the spark-plug gap and set it to the factory specifications noted in the lawnmower owner’s manual.

If you know the plug is good, but you still don’t have spark, the coil likely has failed and requires replacement.

Did You Hit a Rock or Other Obstacle?

We’ve all killed a lawnmower engine after hitting a rock or big tree root.

If your lawnmower won’t start in this scenario, you probably sheared the flywheel key. It’s a tiny piece of metal that aligns the flywheel correctly to set the proper engine timing. Hitting an immovable obstacle can immediately stop the mower blade (and crankshaft) while the flywheel keeps spinning, shearing the key.

In this case, the engine timing is off and the mower won’t start until you pull the flywheel and replace the key. It’s an easy enough job IF you have a set of gear pullers lying around the garage. If not, rent a set from a parts store (or buy one…there’s never a bad reason to buy a new tool) or visit the dealer.

My Lawnmower Starts But Runs Poorly

If you finally get the lawnmower started, but it runs like a three-legged dog, try cleaning the carburetor with AMSOIL Power Foam. It’s a potent cleaning agent designed to remove performance-robbing carbon, varnish and other gunk from carburetors and engines.

Add Gasoline Stabilizer to Avoid Most of These Problems

Which sounds better? Completing all these steps each year when your lawnmower won’t start? Or pouring a little gasoline stabilizer into your fuel tank?

Simply using a good gasoline stabilizer can help avoid most of the problems with a lawnmower that won’t start.

AMSOIL Gasoline Stabilizer, for example, keeps fuel fresh up to 12 months. It helps prevent the lighter hydrocarbons from evaporating to reduce gum and varnish and keep the fuel flowing. It also contains corrosion inhibitors for additional protection.

I have a five-gallon gas can in my garage from which I fuel two lawnmowers, two chainsaws, two snowblowers, a string trimmer, an ATV and the occasional brush fire. I treat the fuel with Gasoline Stabilizer every time I fill it so I never have to worry about the gas going bad and causing problems.

You can also use AMSOIL Quickshot. It’s designed primarily to clean carburetors and combustion chambers while addressing problems with ethanol. But it also provides short-term gasoline stabilization of up to six months.

Use a Good Motor Oil for Your Lawnmower

Although motor oil has no bearing on whether your lawnmower starts or not (unless you don’t use oil at all and seize the engine), it pays to use a high-quality motor oil in your lawnmower.

This is especially true for professionals or homeowners running expensive zero-turn or riding mowers.

Lawnmower engines are tougher on oil than most people realize. They’re usually air-cooled, which means they run hotter than liquid-cooled automotive engines.

They often run for hours in hot, dirty, wet conditions. Many don’t have an oil filter, further stressing the oil.

In these conditions, motor oils formulated for standard service can break down, leading to harmful deposits and reduced wear protection.

For maximum performance and life, use a motor oil in your lawnmower designed to deliver commercial-grade protection, like AMSOIL Synthetic Small-Engine Oil.

Its long-life formulation has repeatedly demonstrated its ability to safely exceed original equipment manufacturer (OEM) drain intervals in the toughest conditions. It provides an extra measure of protection when equipment goes longer between oil changes than is recommended by the OEM.

Signs You Need to Repair or Replace a Mower That Isn’t Cutting It

Lawn mowers have striking similarities to cars. Engines, transmissions, sparkplugs, and filters all wear out or need replacing from time to time. The debate between replacing or repairing your lawn mower often comes down to the same principle: Is your lawn mower totaled or is it worth the cost of repairs?

Luckily, even some of the most common mower issues are manageable DIY fixes. Here’s how to decide whether it’s time to repair or replace your mower.

When to Repair Your Lawn Mower

Whether you’ve owned a riding mower for just a couple of years or inherited your dad’s push mower, the cost is key. The cost of a new lawn mower ranges from 160 to 3,000. Lawn mower tune-ups and repair costs, on the other hand, go anywhere from 10 to 250.

In other words, your model will play a large role in whether it’s worth hanging on to an old clunker. Here are some common scenarios to consider.

The Warranty Still Applies

According to Consumer Reports, manufacturer and extended warranties for mowers range between two and five years. Make sure you read the fine print before heading to the store, however. Some warranties only cover material and manufacturing defects—not the cost of common upkeep like filter replacements. Still, if you just purchased a mower and it’s already on the fritz, it’s worth checking if it’s a general imperfection.

It’s Time for a Tune-Up

Give your lawn mower some TLC at the end and the start of the grass-growing season. A simple tune-up can help you avoid unnecessary repairs or eventual replacement. Be sure to:

• Empty the gas tank before the winter
• Sharpen your blades
• Remove grass buildup from base of the machine
• Switch the oil
• Oil the axle
• Clean the filter

You can also bring your machine to an experienced local lawn mower repair person who can check some of the more common fixes below as well and start off your season with success.

You Need a New Spark Plug or Ignition Switch

The spark plug and ignition switch are both low-cost replacements that you can often manage on your own. Spark plugs only cost about 10 and ignition switches cost between 10 and 25.

Signs of a faulty spark plug may be that your mower doesn’t turn on at all or that it turns off suddenly. Ignition switch problems can keep your mower from turning off.

April showers may bring May flowers, but a bit of pre-spring gardening will bring even more blooms

It’s Time to Replace the Filter

If your lawn mower has suddenly turned into a gas-guzzling creature, you may need to clean or replace your filter. Even if you already replaced it during your annual tuneup, filters can become clogged mid-season if you’re working your mower more than usual. A clogged or damaged filter can force the motor to work overtime, thus using up more gas.

You Need Gas or a New Battery

Both gas-dependent and eclectic cordless lawn mowers depend on a power source. If you can’t get your lawn mower to start, it could be something as simple as topping up your gas or replacing the battery.

Lawn mower batteries range from 35 to 250, still typically less than most new battery-powered mowers.

Take the guesswork out of keeping your lawn pristine throughout the growing season

Another Small Part Needs Fixing

In reality, there are many small parts that are both affordable and relatively easy to order online and replace yourself. However, always read your mower’s user manual to purchase the right part and to properly disconnect the power before attempting DIY repairs.

Common cost-effective lawn mower repairs that beat replacement includes:

• Dirty or broken cooling fins
• Broken or stuck flywheel brake
• Blades blocked by debris
• Cracked oil tank or oil tank cap
• Cracked gas tank or gas tank cap
• Damages drive belt

When to Replace Your Lawn Mower

Do you have a sneaking suspicion that it’s time to put your lawn mower out to pasture? There are, unfortunately, a few major repairs and some scenarios that aren’t always worth the cost of the mower.

It’s Than 10 Years Old

The standard longevity of a lawn mower ranges from seven to 10 years. Mechanical push mowers are so simple that they could last much longer if you keep the blade’s shape and frame oiled. Once you make it past the decade mark with gas and electric mowers, there may be a better model on the market for both efficiency and for keeping upkeep to a minimum.

The Engine is Shot

One of the most important elements of a mower is its engine. And much like a car, replacing it can rival the cost of the mower itself. If the mower needs full replacement—and not just the replacement of individual parts—you’re looking at materials costs alone upwards of 1,000.

You Need a New Transmission

A new transmission will cost less than a new engine—usually between 400 and 500—but if your lawnmower is nearly the end of its estimated lifespan—and if you only need a 500 new model—then it’s best to start fresh.

The Model No Longer Meets Your Needs

If you recently moved to a home with a multi-acred backyard and still have a small push mower, it may be time to upgrade. Not only will the blades, oil, filter need more frequent upkeep, but you could save money by upgrading to an eco-friendly eclectic model that can handle large lawns with less power.

On the other side of the coin, let’s say you’ve finally decided to switch to local landscaping services that bring their own riding mower. If you have a large machine that’s just going to rust in the shed, consider trading in your mower for a small model that requires less fuss.

You Spend Time Repairing Than Mowing

Do you find yourself ordering lawn mower parts online every time you take your machine out of the shed for a season? While DIY repairs can save time and money, reconstructing all the small mechanisms of your mower can add up over time. Be sure to keep a record of how much you spend on your mower in a given season and double-check that it didn’t add up to the cost of a shiny new model.

So you are trying to get the lawn mowed, and your trusty mower won’t start?

How frustrating!

The lawn needs to be mowed, but the tool you need the most is not up to the task.

Good News! Most of the time a mower will start after some basic troubleshooting.

So what should you do next?

Here are a tips on some quick troubleshooting.

If you have a push mower this can be pretty simple.

Let’s take a look at the 5 steps you can take to get your mower up and running.

Start with the basics…. does it have gas in it?

Silly question, I know, but double check.

Time to check the air filter-

Take the air filter cover off, and remove the filter.

The air filter cover will be a plastic rectangle usually on the left or right side of the motor. Though, sometimes they are on the front. You may need a screwdriver to get the cover off, but most of the time they pop off easily, or have a fastener that can been removed by hand.

Now remove the filter, it could be stopped up with debris and this could be the problem, lightly tap the filter against a concrete surface to remove the debris, then use a vacuum cleaner to clean the rest of the debris.

While the filter is off try to start the mower quickly. Sometimes the filter gets covered in fuel, or is just too dirty for it to start.

Not recommending this, but in my experience have run a push mower for over a year with no air filter. I had to remove it to start the mower. Here’s the thing, the mower deck fell apart before the engine ever did.

IF the filter is torn, or your mower only starts when it is off you will need to replace. The Home Depot, Lowes, your local hardware or auto store should stock them. If you have time to wait, do a search online, enter the mower make and model into Google and you should be able to find it.

If you are having difficulty with the filter check out this lawn mower air filter guide.

Still nothing? Try Starter fluid.

Bad gas, clogged lines, and flooded motors are common issues for a mower not starting.

Now that you have cleaned the air filter, try spraying some starter fluid into the engine.

Behind the air filter there is a hole. Spray the starter fluid for 2-3 seconds into the hole behind where the filter sits. Then quickly try to start the mower.

It would be best if someone helped you pull on the starter cord repeatedly while you spray the fluid into the engine.

Most of the time this will get it started. Once you get it running, spray some of the carb cleaner into the carburetor while it’s running, this will clean the carb and prevent issues down the road.

Careful while you do this the blade is spinning!

Nothing again? Clean the carburetor and gas lines.

Water in the gas line, or just plain bad gas will prevent the mower from starting.

In most cases you can remove lower part of the carb by removing one bolt, which is located at the lowest part of the carb, see the photo below.

But first! You will need to drain the gas tank, assuming you have bad gas or water in the tank, you need to empty the entire tank.

Now that the gas has been removed, its time remove that bolt at the end of the gas line below the air filter. You can undo the bolt (see photo below) while the carb is still mounted on the mower. Keep in mind gas will come out. Once the bolt and reservoir are removed, flush the lines with good gas (safely and legally). Also clean the gas bowl with good gas.

Put it all back together, and fill it with good gas. Will it start now?If not, cleaning the entire carb takes longer, but may be necessary. Use this guide to do a complete carb cleaning.

By now I assume most of you are cutting your gas, but if none of that works….

It’s time to check the spark plug,

The spark plug will be on the front face of the engine and will have a rubber boot with a wire coming out of it that is connected to the tip of the spark plug. Make sure that rubber boot is connected properly.

Try starting again, if you still have no luck.

Most people don’t know this, but it’s time to remove the spark plug and replace it. You will need a spark plug wrench. If you don’t have one they can be purchased in the lawn and garden section of any major store, or at any auto parts store.

Remove the plug and take it to an auto parts store, and they will be able to match it up with the correct plug. Reinstall the new plug and try to fire it up again.

Sadly, if you are still here, then you could have more serious issue such as an internal motor problem or a bad carburetor.

Then it’s time to take it to a professional.

What’s the point?

If you have used these 5 Steps,

• Check for gas
• Check the air filter
• Try starter fluid
• Clean the carburetor
• Change the spark plug

And it still won’t start you may need a new mower.

Here’s why, in most cases when it comes to a push mower it is not worth spending the money to have a professional repair it. A decent push mower can be bought for 200-500.

IF you drop it off at the lawn mower shop it’s going to be a minimum of 50 to look at it ,and before you know it you could possibly have a 200 repair bill in a mower that is not worth that.

I hope these tips helped out, and get you back running again.

Hi, I’m Gene Caballero and I’m the co-founder of GreenPal. At GreenPal, we’re helping hundreds of thousands of Americans solve one of the trickiest problems: a reliable, fast, and affordable way to get lawncare taken care of. On behalf of GreenPal, I’ve been featured in the Indianapolis Star. the Sacramento Bee. Entrepreneur. Inc.com. and dozens more. Please feel free to say hi on or connect with me on LinkedIn.