Starting A Lawn Mower That Has Been Sitting For Years | A Complete Guide

Sometimes it is just a matter of cleaning the spark plug to get your sitting lawn mower running again.

Having a lawn mower is a must if you want to keep your lawn looking at its best and save plenty of time while cutting your grass. However, if your lawn mower has been sitting idle for some time, it sometimes won’t just start. Many people deal with this issue, and it is pretty frustrating. The problem is especially noticeable when you take your lawn mower out after a long period of inactivity through the winters.

Starting A Lawn Mower That Has Been Sitting For Years | A Complete Guide

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So, how do you start a lawn mower that has been sitting idle for months? Well, don’t worry, and certainly, do not swear at your lawn mower. There’s no amount of swearing that will fix it! Your mower is alright, and it just needs a bit of fixing. Unfortunately, many MANY problems can arise when machines are left idle.

The most common reasons behind a sitting lawn mower that won’t start include static parts being jammed due to long periods of inactivity, a dirty spark plug, clogged air filter, blocker fuel filter, moisture in the fuel tank, old gas went bad, dirty carburetor, dead battery, and a loose brake cable.

So, all you have to do is find the root cause, and you have already fixed half of the problem. However, sometimes the problem behind a sluggish lawn mower not starting is not apparent. In that case, you might need professional help.

Nonetheless, most of these problems are easy to fix, and here is how you can do it!

How Do You Start A Lawn Mower That Won’t Start?

Check & Change Engine Oil

Check & Change Engine Oil before Start a Lawn Mower

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If you go long enough without an oil change, it could result in complete engine failure.

Like all internal combustion engines, the engine of a mower also needs oil to run. Despite being simple, the mower engine has many moving parts that need proper lubrication and cooling. Without engine oil, the engine of your mower would quickly seize, overheat, and be ruined. So, if your lawn mower has been sitting unused for a prolonged period of time, it is probably a good idea to check the mower’s engine oil before using the mower again.

When To Change Lawn Mower Oil?

Keep in mind that only lawn mowers that can have their oil checked and changed are lawn mowers with four-stroke engines. Ideally, you should check and fill the engine oil before every use and if you have bought a new lawn mower, replace the engine oil after the first four to five six hours of use. However, if your mower has been sitting idle through the winter months, you will need to change the oil before use.

You can easily tell if you need to change your lawn mower’s engine oil by looking for the presence of residues and oil color. If you notice that the engine oil has become too brown or black, it is time to change the oil to keep your mower running smoothly. Also, make sure that there is enough oil to keep the mower running.

A mower engine does not require a lot of oil to run, so replacing or refilling the engine oil is cheap. Also, you can do it yourself in less than ten minutes. We suggest you replace your mower oil twice a year: once at the beginning of the season and once before putting your lawn mower away before the winter.

Check & Refill The Gas, Smarty!

Check & Refill The Gas, Smarty to Start a Lawn Mower

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In the excitement of mowing your lawn, you might have forgotten to fill the gas tank!

You must have had the experience of calling tech support to see if they can help you turn on your computer, TV, or any other device. Most of the time, the first question or solution they provide is to check whether or not your machine or device is plugged in! Well, the same goes for lawn mowers as well. So, make sure you have enough gas in the fuel tank to start the mower before you rush to the local hardware store to get it fixed!

However, if the lawn mower still won’t start despite having a full gas tank, it must be because the gas in the fuel tank has gone bad. Gasoline is not a very stable compound. Under your normal garage conditions, gasoline will go bad in a month or two if not used, and you will have to replace the fuel to start your mower.

You can change the fuel in your lawn mower by tipping the mower to one side and dumping the old fuel. However, sometimes it won’t be possible to tip the mower. In that situation, you will have to siphon the gas out of the fuel tank.

Use A Fuel Stabilizer

If you want to avoid replacing the fuel every time you leave your lawn mower idle for a few weeks, you can try using a fuel stabilizer. A fuel stabilizer works by providing a thin protective layer for the gas sitting in a fuel tank.

Fuel stabilizers work by chemically slowing down the oxidation process, which prevents the fuel from going bad. However, if you do not want to use a fuel stabilizer, you can try using TruFuel. It lacks ethanol and stays usable for years.

Check & Clean The Air Filter

Check & Clean The Air Filter to Start a Lawn Mower

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A clogged air filter means less air which prevents the engine from starting properly.

For the proper functioning of a mower, its engine must receive a correct mixture of fuel and air. If the engine is not receiving sufficient air for any reason, the performance of your mower will be affected. Air contains too many particles and fragments, especially when mowing a lawn. These fragments can kill a mower engine very quickly if not filtered. Over time the air filters of a lawn mower get clogged with these particles and pieces, and it also happens if your mower is sitting idle.

A particularly good sign of telling whether or not you have a clogged air filter is to see if your mower starts, works for a while, and then stops. Fixing a clogged air filter is very easy. All you need is some soap, water, and a brush. First, however, make sure that you air-dry the air filter before putting it back into the mower.

So, if your lawn mower does not start even when you have replaced the engine oil and fuel, it is time to check the air filters. In fact, you should check the air filters and engine oil and gas every time you get your lawn mower out to use after keeping it idle for a long time. 

When To Change The Air Filter On A Lawn Mower?

Sometimes the issue is not a clogged air filter that is not letting your mower properly start but a broken air filter that is letting too much dust in and blocking the engine. In such a situation, you will have to replace the air filter with a new one.

Lawn filters are inexpensive. You can easily get a good air filter for around $10 to $15 at your local gardening hardware store or online marketplace. Just make sure you buy an air filter compatible with your lawn mower.

Check The Spark Plug

Check The Spark Plug before Start a Lawn Mower

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A faulty spark plug can prevent the mower from starting or working continuously.

If you have changed the engine oil, replaced the oil fuel, and cleaned the air filter of your lawn properly and still, the lawn mower won’t start, then it is time to check the spark plug. It is not difficult to find. Usually, the spark plug is located at the front end of the mower, especially in the case of a walk-behind or push mower. That spark plug has a wire attached to it and is also covered with black rubber to keep the debris and dust out.

First, make sure that the spark plug wire is in good condition. Next, check the spark plug itself. Sometimes, the problem is just a dusty spark plug tip that you clean easily, and it will be good to go. However, sometimes the spark plug is broken and will need to be replaced if you want to use your mower.

You can easily tell if the spark plug needs to be replaced or not by looking for the signs of corrosion or rust. Especially, look for rust and corrosion at the tip of the spark plug because that is where everything is happening inside the combustion chamber.

RELATED: How To Fix Lawn Mower Sputtering: Common Reasons & Easy Fixes!

How To Replace The Spark Plug On A Lawn Mower?

Experts usually suggest replacing the spark plug of a lawn mower after every twenty-five hours of use. However, if you do not use your mower too often, you can replace the spark plug every season, and the mower will be fine.

While replacing the spark plug on your lawn mower, make sure that you get the right size. Then, all you need is a correct socket wrench, a few twists in the right direction, and the plug will come right off. 

While replacing the spark plug, make sure you disconnect the wire attached to it and ocean the area around it so that debris does not get into the mower. 

Check The Brake Cable

Check The Brake Cable

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A mower brake cable is a specialized safety feature without which the mower won’t work.

Another common reason the mower does not start sometimes after a prolonged period of inactivity is the loosened brake cable. The brake cable is sometimes referred to as a kill switch or zone control lever. It engages or disengages the mower blade and is attached to the handle control of the mower.

When the handle control is depressed, the brake cable tightens, and the mower starts. However, if the mower cable is damaged, broken or loose, it will make your lawn mower temporarily inoperable. You can easily see if your brake cable needs replacing or tightening by pulling on it.

If the cable feels loose, tighten it a bit, and you are good to go. However, sometimes the cable is damaged or broken and not safe to use. In that case, you will need to replace the brake cable on your lawn mower before using it.

How Do You Replace A Lawn Mower Stop Cable?

Finding the suitable brake cable for your lawn mower is perhaps the most challenging part of replacing it. Make sure you know precisely what mower you are using and buy the right brake cable that is compatible with your mower.

Next, follow the old brake cable down its length and detach it from the mounting mechanisms. Now all you have to do is simply install the new cable and attach it to the mounting mechanisms. 

The process is simple and straightforward, but ensure you take all the precautionary measures. However, suppose you are unsure about replacing the mower cable on your own. In that case, it is always better to get expert help.

Check The Carburetor

Check The Carburetor

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The carburetor is responsible for providing the engine with the correct air-fuel mix to keep it running.

The carburetor of a lawn mower is its lungs. It is responsible for mixing the air with the fuel in a correct ratio and keeping the engine running. Your machine can still run without the carburetor; however, it will consume too much fuel, and its efficiency will be significantly lower. When your mower is used too much or when it sits idle for a long time, it can collect dust which can deposit in the form of layers inside the carburetor.

In addition to dust collecting inside the carburetor, corrosion is another common reason why your lawn mower won’t start after sitting idle through the months of winter. Also, if there is fuel in the mower during the period of inactivity, it can evaporate and form sticky residues inside the carburetor.

So, if nothing else seems to work, you might still be able to get your mower running by properly cleaning the carburetor. It is a simple job, and you can do it yourself at home, but once again, if unsure, it is better to hire a professional.

How Do You Fix A Clogged Carburetor On A Lawn Mower?

First of all, make sure that the engine is cool. Following that, remove the filter hood and take off the air filter. Next, shut off the fuel valve and detach the fuel lines. Take the carburetor off and remove the float pin to release the needle and float.

Locate the carburetor intake and outlet ports and use a dedicated carburetor cleaner spray to clean the insides properly. If there is a carburetor bowel, clean it as well. If there are signs of rusting and corrosion, use sandpaper to make amendments.

Finally, let the carburetor dry in the open air and mount it back on your lawn mower. Reattach the fuel lines and also reinstall the filter cover, if applicable.

RELATED: How To Locate and Clean The Carburetor On A Lawn Mower? | A Beginners Guide

Check The Fuel Pump

Check The Fuel Pump

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The fuel pump is responsible for putting fuel into the engine from the fuel tank.

If you have already tried most of the things suggested in this article and your lawn mower is still not starting, you can try replacing the fuel pump. Unfortunately, it is challenging and nearly impossible to repair a fuel pump. Your best bet is to buy a new fuel pump for your mower. It is a lot cheaper than buying a new lawn mower, though!

There are many reasons why a fuel pump might stop working. It could be the issues with the loading mechanism or the presence of a leak in the engine chassis, which let’s oil into the fuel pump, causing it to malfunction.

You can tell if your engine has an oil leak if you start your lawn mower and see white smoke coming out of the exhaust pipe. 

Other Problems With The Lawn Mower

Dead Battery

A dead battery is another common reason your lawn mower is not starting after prolonged periods of inactivity. In fact, it should be the first thing on your checklist when nothing else seems to be working. You can either get a new battery or charge the old battery and then try again to start your long resting mower.

Starter Rope Won’t Pull

If you are trying to start your lawn mower after prolonged idleness, you might face issues with the starter rope. It might have gotten stuck due to inactivity, or there might be an issue with the flywheel brake. The flywheel brake is the bar that you hold down on the handle. Make sure it is entirely down, and then pull the starter rope again.

Broken Flywheel

While a broken flywheel is not something you would expect if your lawnmower has been sitting idle for long and not starting again, it could be a culprit in some cases when your mower is not starting.

The flywheel is the spinning wheel that attaches to the mower blades. Sometimes when you hit a hard object when mowing your lawn, it could break and will make your mower inoperable. 

Removing and replacing the flywheel is quite technical and tedious. So, it is better if you hire a professional for this job.

Issues With Compressions

If you have a gas-fired lawn mower, the reason why it is not starting after a long period of inactivity can be the absence of compressed air. Gas-powered lawn mowers need compressed air to function. So, in such a scenario, you will have to go through the compression process and then see if the mower is working.

Final Thoughts

Many people give up on their lawn mower when it does not start after prolonged inactivity. But, if you are reading this article, do not do that. In most cases, the lawn mower is perfectly okay, and all it needs is a bit of maintenance to start working again like usual. So, don’t give up on your mower just yet.

Try cleaning it well, replacing fuel and engine oil, washing the air filter and carburetor, cleaning the spark plug, tightening the brake cable, and see if it starts. If it does not, try taking it to a mechanic and get it fixed. A lawn mower is an expensive machine, and you do not want to keep buying a new lawn mower every year, do you?

Frequently Asked Questions (FAQs)

How do you start a stubborn lawn mower?

Not with cursing and swearing, obviously! The most common reasons behind a lawn mower not starting are spark plug issues, dirty carburetors, and clogged air filters. So, try fixing that, and your lawn mower will probably start running.

Can I leave the oil in my lawn mower over winter?

If you have just recently changed the engine oil in your mower, it is okay to leave it in. However, it is highly recommended that you use fresh oil in the mower when using it after a long period. Lawn mowers do not need much oil, and it is easy to change.

How do you get old gas out of the lawn mower?

One way to remove gas from your lawn mower is to tip it on one side and dump the gas. However, that might be difficult for some types of lawn mowers. In that case, you can siphon the gas out of the fuel tank or use a baster/pipette.

Sources for Further Reading

Lawn mower tune-up – UDAILY, University of Delaware

Lawn mower safety tips – University of Iowa Stead Family Children’s Hospital

Safety Tips for Lawn Mowing – University of Utah Health Hospitals and Clinics

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Morgan Daniels

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