Lawn Mower Repair Guide

Maxim Panych

Maxim Panych



Everyone has had this experience at some point: it’s time to get the yard work done, so you give the pull cord on your trusty mower a yank and… nothing.

So you pull it again, and again, and are never rewarded with the roar of the engine coming to life. It’s frustrating, but luckily it may not be quite as bad as you think.

There are many reasons why your mower might not start, and many of them are surprisingly common and easy to fix yourself. Yes, you may need to make a trip to a local store that carries lawn mower parts, but it will be much less expensive than a repair shop. If you’re familiar with engine repair on any level, your difficulties with your lawn mower may be very easy to fix. Even if you’re not handy around an engine, many of the most common problems that will prevent your grass mower from starting are still very simple to fix yourself with just a few tools and parts.

First, let’s take a look at some of the differences in mower models, because the many different features and brands of lawn mowers may make it seem like there aren’t any general solutions when in reality, there are.  Then, we’ll talk about how to fix the most common problems yourself.  Finally, we’ll discuss lawn mower maintenance you can perform to help prevent future problems.

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Grass Mower Won’t Start?

A lawn mower engine is simple compared to larger engines, which is good news; this means that there are fewer things that can go wrong enough to prevent your mower from cranking. If your Briggs and Stratton lawn mower won’t start after sitting idle for a while, or your mower worked fine last weekend but stubbornly refuses to crank now, there are simple reasons why. Let’s see if we can figure out what’s preventing you from getting that grass trimmed.

Lawn Mower Refuses to Start
Diagnosis for a Poorly Running Mower
Maintaning and Fixing Fuel System

Open each picture in a new tab of your Internet browser to see the infographic in a full size.

Keep in mind that this isn’t meant to be an exhaustive guide to every potential problem your mower could experience; if none of the steps that follow gets your mower back up and running, you may save time and stress by taking your mower to a small engine repair shop.

7 Steps to fixing a lawn mower that won’t start

Step One: Check Fuel Levels

The first step is the easiest; check the fuel in your mower. Of course, if the fuel tank is empty, your mower won’t start, but that’s not all that we mean. Check the fuel in the tank for any floating debris, and check its odor. Yes, you need to sniff your fuel tank for this step.

If your fuel doesn’t smell right, you may have a problem with your lawn mower carburetor. Before we start dismantling your engine, though, let’s check a few more things.

Step Two: Check Spark Plugs

The next most common reason for a mower to not start is a problem with your spark plugs. A problem in this area can take two different forms: you could either have trouble with your magneto (the spark generator in your engine) or with the spark plug itself.

You can: pick up a spark plug checker at most hardware or tool outlets or any place that carries auto or lawn mower parts. Once you have one on hand, plug the checker into your engine in between your spark plug and the cable, and then try to start your mower. If the checker doesn’t light up with a glow, then your problem might be with the magneto or you might have a wire shorting out, preventing the spark from reaching the plug.

If your checker shows that you are getting a spark, give the spark plug itself a good examination. Make sure the plug isn’t fouled with grease or residue; this can prevent your plug from making a proper connection and prevent your mower from starting.

Step Three: Check Air Filter

If your spark plug and harness are working, the next step you’ll want to take is to check the air filter. A dirty air filter can prevent your engine from drawing enough air into its chambers to combust. The air filter can become clogged from long use or oil residue. Of course, this is a very simple fix; if your air filter is dirty, replace it with a fresh, clean one, and then try to start your mower again. If it still refuses to crank, the next thing to check could be a bit more complicated, but it’s another common problem that will have to be addressed no matter what.

Step Four: Check Fuel Tank for Water

Let’s head back to the fuel tank, but this time we’re not looking for funny odors; we’re looking for water in your fuel. Most people think that there’s no way their fuel can be contaminated with water since they keep their fuel can be sealed tightly and their mower stored in a garage or other indoor area.

However, your engine can build up quite a bit of water in the fuel tank from simple condensation as the temperature changes around the mower. To fully investigate this, you’ll need to drain the fuel from your mower into a glass container. If water is present, it will float to the top, as it has a lower density than the fuel.

You can: just tip your mower on its side to drain the fuel, but be aware that this can cause oil to leak into your engine and potentially cause additional problems. The safest method is to remove the fuel tank from the engine and then drain the fuel into another container.

Once you’re done, if there’s water in your fuel – and it will most likely be obvious – you’ll need to thoroughly clean and dry your fuel tank, but that’s not all. You’ll also need to remove the bowl from underneath the carburetor to completely clean and dry it as well. This may involve removing the carburetor, depending on the model of your mower.

Step Five: Check Auto-Choke Spring

If you’ve completed that step and either found no evidence of water in your fuel or cleaned it properly if there was, and your mower continues to refuse to start, another common problem is a spring. Specifically, it’s the spring attached to the auto-choke.

Most newer models of grass mower feature an auto-choke that helps regulate the flow of fuel into the carburetor. This is a metal bar running out of your carburetor, attached to your engine by a spring. If that spring is broken or stretched out until it is too loose, it will prevent your engine from getting the proper amount of fuel to crank.

You can: check this by locating the bar; if it’s not there, you may not have an auto-choke feature on your lawnmower. If you do find it, however, you should be able to push it in with your finger. If it gives you resistance or has a rough movement to it when you gently push the bar, your auto-choke spring most likely needs to be replaced.  Fortunately, this spring is easy to find anywhere that carries lawn mower parts.

Step Six: Check Blade and Flywheel Key

If you’ve made it to this point and your grass mower still isn’t starting, there’s one last thing to check before you start to Google “find lawn mower repair near me.” If you ran over a large object such as a large rock or tree root the last time you used your mower, this could have bent or damaged your blade. If the blade won’t spin clearly, it will have to be replaced before your mower will run properly.

Also, your flywheel key could be broken. This is caused by the same situation: the stress of your spinning blade suddenly stopping due to a foreign object such as a rock or root could cause this to break. If so, you’ll need to replace the flywheel key and retime your flywheel before your lawnmower will start.

Step Seven: Consult a Repair Professional

Unless you’re familiar with that process, it might be worth the expense to take your mower to an experienced lawn mower repair shop. That may also be a good idea if you’re not comfortable removing the carburetor yourself, as you might need to do if your fuel smells funny or you need to remove the fuel bowl to drain and clean it of water.

The good news is this: while there are always things that can go wrong with your lawnmower, there are some things that are easily preventable with proper care and maintenance.  Let’s look at some recommendations to prevent any problems with your mower in the future.

Lawnmower Maintenance

As we’ve said, your best bet is to head off problems before they start.  While that isn’t always possible, there are a few things to keep in mind to ensure that your mower stays in good shape as long as it can.

Prepare Your Mower for the Off-Season

Maintain the Tires

Check Oil and Filters Regularly

Keep an Eye on the Blade

Prepare Your Mower for the Off-Season

If it has been sitting dormant during the winter, it’s common for a lawn mower to fail to start if it wasn’t winterized properly. After your last use of the mower for the year, there are steps you need to take to make sure you’ll have no problem firing it up again in the spring to keep your lawn looking its best.

Before putting your lawn mower to bed for a long winter’s nap, drain the fuel from the engine. Over the winter, old fuel can turn into a thick gunk inside the carburetor and clog the fuel ports in your motor. Refill the engine with fresh fuel and add a fuel stabilizer to your mix. This will prevent the fuel gumming up the carburetor before you’re ready to use it again.

Also, check your owner’s manual and follow the recommended process to follow to change the oil in your engine. You may want to drain it before storing it, but most likely replacing the old oil with fresh oil will keep your engine safe over the winter.

Maintain the Tires

While loose or flat tires aren’t going to prevent your engine from starting, of course, they can seriously hamper the performance of the lawnmower when it’s time to cut the grass.  If the tires are pneumatic, check the pressure regularly with the same gauge you use for your car tires.  The maximum pressure in PSI will be listed on the sidewall, so be careful not to overfill them.

Lawn Mower Wheels
Tires Checking

In addition the pressure, you’ll also want to regularly check the state of the treads.  If they’re excessively worn down or if you spot cracks that are signs of dry rot, it may be time to replace the tires.  Also, while most mowers are built to have a certain amount of wobble, too much of it can mean that you need to check both the nuts that attach the tire and the axle nut itself.

Check Oil and Filters Regularly

During the months when your mower is being used regularly, there are still things that should be done to it running in tip-top shape. Regular attention can keep you from spending a frustrating few hours fixing your mower before beginning your lawn care.

Lawn Mower Oil Checking
Oil Checking

As we said earlier, the air filter is one of the most important things in your engine. It prevents dust, dirt, and debris from getting to the carburetor, which can cause serious problems. Even if it’s doing its job, though, the air filter should be checked on a regular basis; if your air filter becomes clogged, your engine might have trouble starting or running.

If your model of mower uses a paper filter (usually a pleated paper inside a frame), it will have to be replaced after every 25 hours or so of running time for your engine. If your engine uses a foam air filter, it can be reused after a good cleaning with hot water and detergent. Once you clean it, it will need to air dry before being placed back into your engine for use.

You should also check and change the oil on a regular basis, just like you do with your car. The more use your oil has seen, the darker it will be. Your mower’s oil should be changed at least once each mowing season or about every fifty hours of operation. Make sure you use the exact oil that is recommended by the manufacturer of the engine in your mower, or you could end up causing damage to your engine.

Check the oil filter and replace it if it needs it. Fuel filters shouldn’t be cleaned; pick up a new one and throw the old one out. Keep your engine degreased with a spray degreaser.  Not only will this keep your grass mower looking good, but it will help keep gunk from working its way inside your engine.

Keep an Eye on the Blade

One part that many owners don’t think to check when servicing their mower is the blade. If your blade is damaged, it will decrease the efficiency of your mower.  More than that, a broken blade can be dangerous. If your blade has any dents, bends, or damage of any kind, replacing it is a good idea. When replacing the blade, use the type and size blade recommended by the manufacturer. Their recommendations are there for safety reasons because a blade of an incorrect size could cause injury.

Lawn Mower Blade
Blade Checking

If your blade looks fine but is a bit dull, you need to sharpen it. Ideally, you should sharpen your blade every season and replace it every three years even if it looks okay. There are only so many times a blade can be sharpened before it runs the risk of a break or bend.

Here’s another reason to keep your blade sharp: if your lawnmower blade is dull, it’s not cutting your grass, it’s tearing it. This can lead to a ragged looking lawn once you’re done, which is less than ideal, of course.  While it’s not as important as your safety, the appearance of your lawn is part of the reason you purchased the mower in the first place.

Read: How to Get Your Lawn Mower Ready for Spring

Need a New One? The Most Popular Lawn Mower Models

There are many recognizable brands that manufacture excellent lawn mowers.  Snapper, Toro, Craftsman, Troy Built, Poulan and Briggs and Stratton are among the most popular, and with good reason; these brand have developed their reputations on the quality of their machines. While there are some minor differences among the different makes of lawnmower models, most are similar enough in their basic functioning that the steps in this guide will apply to any of them.

Snapper Lawn Mower
Toro Lawn Mower
Craftsman Lawn Mower
Troy Built Lawn Mower
Poulan Lawn Mower
Briggs and Stratton Lawn Mower

The Snapper P2185020, for example, has a unique innovation. This model has an insert in the gas tank cap that releases a steady drip of fuel preservative into the tank, extending the life of your lawn mower and increasing its fuel efficiency.

While there are still traditional push mowers available, self-propelled (or walk behind) mowers increase in popularity every year. Of course, this adds a new level of complexity to lawn mowers, along with a new set of features to consider.

For example, the Husqvarna HU800AWDH is considered one of the best “all wheel drive” walk behind mowers on the market.

Meanwhile, the Honda HRX217K5VKA has been named to many “best of” lists for lawn mowers in the category of “most maneuverable.”

Not all mowers are all-wheel drive, of course; the Troy-Bilt TB220, for example, is a front-wheel-drive mower, while other makes and models on the market are rear-wheel drives. The one that’s right for you will depend on the job you want it to do, and the property you want it to mow.

Also, most mowers can be equipped with bagging systems to collect the clippings as you mow, like with the Craftsman 37705. This mower is considered by some to currently have the best bagging system on the market, but this may not be the most important consideration for you.

In each of these cases, there are individual systems that may or may not be present on your mower. However, if you want to learn how to fix a lawn mower that won’t start, the model or its features may be less important than you might think. Let’s take a look at some common problems and the grass mower repair steps you should take to get your mower running again.

Final Thoughts on Lawn Mower Repair

Grass Mower Maintenance

This article was written in the hopes that it will save you time, money and heartache when your mower refuses to start. As we said earlier, this isn’t an exhaustive list, but it does include the most common reasons you could have this problem.

While some of the steps above may seem complicated, they’re not as difficult as they sound. In fact, some are quite simple. You may think that a problem bad enough to prevent your lawn mower from starting couldn’t be as small and easy as some of the ones listed here, but that’s most often the case.

This leads to one final point: just because these problems are simple to diagnose doesn’t mean you’ve necessarily done anything wrong while caring for your mower. While they are more simple than larger ones, the engines that power grass mowers are still complex pieces of machinery, and easy-to-fix problems are experienced by more lawn mower owners than you think.

Having said that, your skill and comfort level with engine repair will determine what types of problems you’ll be able to fix yourself. While you can handle almost all the issues in this article easily, remember that there can be more than one thing wrong. Check them all until your lawn mower starts, or it’s time to say “I wonder where there’s lawn mower repair near me?” as you load your mower up.

Lawn Mower Repair Near Me

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