How frequently should I change my lawn mowers spark plugs. Lawn mower not sparking

Why is My Lawn Mower Spark Plug Covered in Oil?

Spark plugs in lawn mowers can occasionally get wet with oil or other fluids, and if you have never dealt with this before, it can be unnerving. This article will outline potential underlying causes of this to help you get your mower up and running again. There are a few potential reasons for a wet spark plug in your lawn mower, but it’s most likely because the plug has overheated due to ethanol in the gas, and the combustion chamber is flooding with oil, or there is water flooding the engine or the fuel and oil tanks. There are a few other potential reasons for spark plug flooding, and it may require servicing to thoroughly clean it. There are a few remedies that you can do yourself, as well as important precautions to take to prevent this from happening again in the future.

What Causes a Spark Plug To Get Wet With Oil in the First Place?

Regardless of the chain of events that led to your mower not igniting, be sure to take note of these reasons for future reference. Always try to be up to date with servicing your mower and changing out old parts, and be sure to not flood the engine by priming it too many times when trying to start the mower.

Should I Fix it Myself, or Take it to a Technician?

You can certainly try to fix your mower by yourself if you feel comfortable with a repair. There are several steps to determine the specific problem with your mower, as well as ways to fix it.

You may have to make a few extra trips to your local lawn and garden store in the process, but the result will mean saving a considerable amount of money.

This being said, taking your mower to a technician is always a good step as they have the parts and fluids on hand. It will also mean just one trip to the specialist and it usually doesn’t take long.

You won’t have to deal with the potential cleanup of draining oil and gasoline from your mower or bother with tools required to disassemble your mower.

As with all appliances and machines, if you have something that costs more money, it is worth investing the capital to have a technician fix it such that you don’t create a more serious problem.

But if you feel comfortable taking a few things apart and trying some of these quick fixes, you can save a lot of money in the long run.

How Do I Fix it?

There are multiple steps you can take to fix your mower. You’ll need to purchase starter fluid at your local home and garden store and possibly a new spark plug as well as fresh gasoline and oil.

Here are four steps you can take to fix the problem yourself that will save you money at a technician:

Starter Fluid

Take out the air filter and spray starter fluid down the carburetor. Be sure to turn off the choke before you do this.

Start the mower if you can. If it does start, turn it off again and clean out the air filter before putting it back together. If it doesn’t start, move on to the next step.

Replace the Oil and Gas

Drain the gas and oil. As always, be careful about open flame near the mower or your person when doing this!

The easiest was to do this is by disconnecting the fuel/oil line and draining it into a bucket. If you don’t know where these are, or just aren’t comfortable doing this, you can also use a fuel transfer pump such as the Koehler Enterprises RA990 (buy on Amazon).

It’s also a good idea to remove the spark plug to prevent accidental ignition. Replace the oil and gasoline with fresh fluids and try starting it again.

If it doesn’t start, you may want to try replacing the spark plug.

Replace the Spark Plug

You may have to go back to the store for this since you likely wouldn’t have purchased one on your first trip, but you’re still saving a good deal of money. If the mower doesn’t start, move on to the next step.

Clean the Coil and Magnets

Turn the fuel valve to the “off” position and check the coil for rust. If it’s dirty, use sandpaper or a rough brush to clean it, and clean the magnets on the flywheel.

Replace the coil and make sure to tighten it to its original position.

How Much Does a Repair Cost?

Starter fluid is about 10 and usually the first item you will buy when first addressing the problem. A new air filter ranges from 10-15 in case you decide to replace that as well, but usually starter fluid or draining the gas and oil will fix your problem.

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If you have to replace a spark plug, they are not expensive, ranging from 5-10 and sold in various lawn and garden stores.

Make sure that you bring the old spark plug with you to the store to talk to an associate to determine the exact right one for your mower.

If you take your mower to someone to do the repairs for you, the cost will be much more expensive than doing it yourself, but possibly a worthwhile price if you’re nervous about doing something like this at home. The parts will usually range from 20-25, and the labor will range from 60-80, depending on where you live.

How Can I Stop This From Reoccurring?

A first and important step is to never leave your mower out in the rain. Rain can get into compartments and even the fuel or oil and cause the mower not to start.

Mowing wet grass after rain or early in the morning with dew can also lead to flooding the engine and should be avoided. Try to avoid over-priming the mower when starting it.

If you flood the engine with oil, then the spark may not reach the ignition, and you will not be able to start the engine. If you do this repeatedly, it will damage the engine or spark plug over time.

Be sure to replace your oil annually. If you consistently change the oil every 50 hours that you use it, you will keep it running smoothly and avoid fluid build-up that causes malfunction.

As with all expensive pieces of machinery, keep track of how often you use it each year and be sure to follow best practice guidelines for replacing parts and fluids.

How to fix a lawnmower no spark

Hi! I’m Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I’ve created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!

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How frequently should I change my lawn mowers spark plugs?

NO! This is a common misconception, below is what you need to know.

With so many factors to maintain your lawnmower properly, it can quickly become overwhelming.

And one of the many questions you may face while maintaining your lawnmower is how often should you change your spark plugs?

This is crazy, but we found out that there is a lot of misinformation on how often spark plugs need to be replaced.

So naturally, we did some digging, and we also reached out to some lawn care pros to ask them what they think.

Below you will find EVERYTHING you need to know about how often you should be replacing your mower’s spark plugs.

In a nutshell: How often should lawn mower spark plugs be replaced?

In short: As a rule of thumb, the average homeowner should be ok if they change their spark plugs out once a year.

The same is true of all your lawn care equipment in general, including commercial weedeaters.

Here’s the deal, most websites appear to recommend that you should replace your spark plugs every 25 to 30 hours of operation.

Get this, the lawn care professionals we spoke with had something entirely different to say.

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With well over 50% suggesting that they only replace their spark plugs ONLY once a year.

Which would suggest that spark plugs operate efficiently for much longer than other mainstream sources suggest.

But we will cover that more in a minute.

Why do I need to change the spark plugs in my lawnmower?

Think about it, as the ignition source for your lawn mower’s fuel. Your spark plugs create a spark 1000’s times during the process of cutting your lawn.

And during the process of igniting fuel over and over and over. Your spark plugs can get deposits built upon them and they will eventually become too corroded to ignite fuel efficiently.

Other potential reasons you are spark plugs may need to be replaced include:

Simple Trick To Diagnose A Bad Ignition Module (Coil) On A Lawnmower, Chainsaw, Weedeater Etc.

Whatever the case, your spark plugs should be changed on a regular basis to prevent efficient lawn mower operation. This is simply a part of proper lawn care.

But how often should you change your spark plugs?

What is the industry standard?

Here’s the deal, for one reason or another, most sites recommend changing your lawnmower’s spark plug every 25-30 hours.

While I am not sure why this misconception has taken over, it may be due to this article by Briggs and Stratton.

The article states that you should “check and/or replace” your spark plug every 25 hours.

Somehow the ‘check and/or” part got overlooked in other articles who mistake that “the life of a spark plug is 25 hours”Source

However, in all fairness, the Google Search result is a bit misleading, and shows why a deeper investigation into search results is a must!

Is Briggs and Stranton intentionally misleading consumers to make more spark plug sales?

Look in my experience, spark plugs last 100’s of hours… easily. Changing your spark plugs out every 25 hours is way too frequent.

However, it’s difficult to come up with a better number on our own. So we reached out to other lawn care pros to see what they recommend.

Here is what they had to say.

What do the lawn care pros say about replacing a spark plug on lawn care equipment?

Across the board, the resounding response from lawn care providers was that they changed their spark plugs annually. With 64% reporting to us that they only changed their spark plugs once a year.

This number suggests that spark plugs last MUCH longer than 25 hours.

Think about it we are talking about lawn care professionals. So if they run their mower for a minimum of 20 hours a week for 39 weeks of the year for example. That means spark plugs easily last over 780 hours before needing to be replaced.

What did the rest of the lawn care professionals say about changing their spark plugs?

Well, the second most popular response we received was 30% of lawn care pros stating they NEVER change their spark plugs.

Finally, 3% of lawn care providers said they changed their spark plugs after the ‘recommended’ 25-30 hours of use, and another 3% reported to us that they swap spark plugs out on a monthly basis.

Remove Spark Plugs Regularly to Prevent Seizing

Look, whether your spark plug ignites the fuel or not is one thing. But one huge issue that can occur when your spark plugs are not maintained is seizing.

Here’s the deal, a bad spark plug isn’t a huge problem, but a seized spark plug can be a major headache. And could potentially cause other problems down the road.

Spark plugs can seize inside the engine block if they are left in too long, or improperly installed.

So, even if your spark plugs are still good, you want to be sure to remove them annually and add an anti-seize agent at the very least.

Spark Plug Maintenance at the End of the Day

Simply put, if you are a homeowner you probably can’t go wrong changing out your lawnmowers spark plugs annually.

Most homeowners use their lawnmowers well over 30 hours annually. So it simply makes sense to swap out your spark plugs on an annual basis.

On the other hand, if you are a lawn care pro, only changing your spark plugs once a year may not be enough. And you do risk sacrificing your lawnmower’s performance by not changing your spark plugs frequently enough.

While it’s a fair assumption that changing out your spark plugs weekly is a bit overkill. You may want to consider changing your spark plugs on a monthly basis if you are a lawn care vendor.

But the reality is, your mowers spark plug goes mad, it’s not a difficult fix. At least if you happen to carry spares on hand.

Want more to read? Check out this article on how to winterize your lawn care equipment.

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. and dozens more. Please feel free to say hi on or connect with me on LinkedIn.

My mower won’t start

Starting problems with your lawn mower fall into 2 basic causes: fuel problems and ignition problems. The following is a simple checklist you can follow to help isolate a possible cause. This is not an exhaustive guide and certainly not a repair manual. However, there a few steps you can take before taking it to the repair shop for a thorough fix.


This is the first and most obvious thing to check, especially if you weren’t having startup problems last year. Be sure that the machine has an ample supply of fresh fuel. It’s amazing how often people will get their mower out of cold storage the first warm day in spring and find their mower just won’t start. Forgetting that they left the fuel in the tank from the previous year. Today’s fuels don’t age well. In fact today’s gasoline is much like milk and starts to go bad quickly, often in as short a period as 60 days.


Make sure that the ignition switch is “on”, that all attachments are disengaged and that the transmission is in neutral. Most machines have safety mechanisms that will not allow them to start otherwise. Consult your owner’s manual for the starting procedure for your machine.

Make sure the spark plug wire is firmly attached to the spark plug.

If it still doesn’t start, check for a spark by removing the spark plug and grounding the “hex” part of the spark plug to a bare metal part of the engine. Remove any spilled gasoline that is nearby first, then spin the engine by pulling the rope or turning the key. You should see a blue spark jump across the plug gap. If you have a good hot spark, skip to the carburetor section.

lf the spark is yellow and weak, or there is no spark then the first thing to do is try a new spark plug. Don’t try cleaning the old one. Set the new plug gap to the proper spec (usually 0.030″) and check for spark again. If you do see a spark, install the new plug and try to start the machine.

If there’s still no spark, try cleaning and setting the points on older machines, or replacing the electronic ignition module on newer machines. Before replacing the old module test it by disconnecting all the wires from the module terminal that connect to the kill switches and recheck for spark, if you do see a spark then a wire or switch is probably defective. Also check the flywheel key. That affects the spark timing, usually the key will need replacing if you strike something while mowing and the engine stops.

Checking the carburetor and fuel system

If the fuel is fresh, you have a good spark and still won’t start, you must make sure that fresh gasoline is getting to the carburetor. Make sure that the fuel shutoff valve (if present) is opened, and that the fuel line is not plugged or kinked.

Also be sure the fuel cap vent is open and any screens in the tank are clear of debris. If fuel can flow to the carburetor, carefully place 1 teaspoon of gasoline down the spark plug hole (or a add shot of starting fluid into the carburetor throat). Re-tighten the plug and try to start the machine. If it runs for a second or two, then quits, chances are the carburetor needs to be serviced (disassembled and cleaned inspected, then rebuilt) or you have an air leak somewhere.

frequently, change, lawn, mowers, spark, plugs

Make sure all mounting screws or bolts are snug and gaskets are not missing sections. If the carburetor is a bowl-type check for water in the bottom of the bowl (but do not let the float swing all the way down or the float needle will fall out!).

Hopefully, this will give you a little insight in what to look for if your mower won’t start. Most starting problems are fuel related because the previous year’s fuel wasn’t removed. You may have gone years without removing the fuel at the end of the year without having any starting problems. There is a chemical process called varnishing that puts a coating on the inside workings of your fuel system. Over time this process continually worsens until your system becomes inoperable.


Gasoline can ignite very easily. Work only in well-ventilated areas and away from sources of heat, sparks, and flames. Always wear safety glasses, and be careful of sharp blades. Keep a fire extinguisher nearby.

Where is the spark plug on a lawn mower?

Need to know where is the spark plug on a lawn mower? Learn how to maintain it to keep your machine running reliably.

If you’re wondering “Where is the spark plug on a lawn mower?”, it’s likely your machine has broken and you’ve got an overgrown lawn waiting to be cut. Even worse, maybe it stopped working mid-trim, leaving your grass half-mown.

Repairing your lawn mower isn’t just about getting your garden looking neat and tidy. It’s also a great way to save time and money, because you won’t have to research the best lawn mowers or best riding lawn mowers and splash out on a new model. Mending a damaged machine will also help save a repairable tool from going to waste, which is better for the planet.

Even without a breakdown, experts recommend that you regularly check and clean the spark plug, replacing it each year to ensure your mower always starts reliably – so keep reading to find out how.

What is the spark plug?

The spark plug provides the ignition source for a gas-powered lawn mower engine. It sends an electrical current to the combustion chamber which holds the compressed fuel. This current ignites the fuel, triggering combustion and firing up the engine. If you drive a gasoline vehicle, it will also have a spark plug, as spark plugs are an essential component of a traditional combustion engine. While we recommend seeking help from a mechanic if your car or truck needs a new spark plug, replacing this part on a lawn mower is a relatively easy job you can do at home.

On most of the best lawn mowers (such as walk-behind models), the spark plug is typically located near the front of the engine. Spark plugs are usually concealed behind a rubber cap, which protects the part from dust and debris, including stray grass cuttings. This is connected to a short wire, about a quarter-inch thick. It should be easy to find the spark plug on your mower once you have disconnected this wire, which you can do by hand.

On the best riding mowers, the spark plug is also located near the front of the engine, underneath the hood. You will probably need to unscrew and remove the engine cover to access the spark plug. Once uncovered, you’ll see that the spark plug is near the front of the engine, covered by a cap and connected to a short wire, just like on a push mower.

If you’re unsure, check the owner’s manual to see where is the spark plug on a lawn mower from a specific manufacturer.

Signs of a failing spark plug

Trouble starting the engine. The most common sign of a faulty spark plug is difficulty starting the mower’s engine. If using a push mower, you might find you’re having to pull the starter rope more times to get it going. On a riding mower, you may notice that the engine doesn’t start reliably when you turn the key.

Using more fuel. A faulty spark plug could be the reason you are refilling your lawn mower’s gasoline tank more frequently. If the plug isn’t sparking properly, the fuel won’t burn as fully or as efficiently, which can increase your mower’s fuel consumption. You might also notice an odor of gasoline when using the mower caused by the fuel not fully burning.

Engine cutting out. If the engine cuts out immediately after starting, or runs for a while then stops (leaving you with a half-mowed lawn), the spark plug could be the culprit. You might also notice the engine sputtering or popping.

Visible damage. If you examine the spark plug and spot any signs of damage, it will need replacing.

How to check spark plugs

After locating the spark plug on your mower, you need to remove it to check it. Bryan Clayton, CEO and co-founder of GreenPal, says, “Pull off the wire that goes to the top of the spark plug and use a spark plug wrench to take it out. Then you can look at the tip of it and see if it’s dirty or burnt. If it is, you need to clean it or replace it.”

frequently, change, lawn, mowers, spark, plugs

Other common indicators of wear and tear can include a center electrode with a rounded top (this should be flat), cracks in the porcelain sheath that protects the spark plug, or pitting on the firing electrode. A spark plug that’s in good condition will be a light gray or tan color. If the spark plug is covered in black carbon residue or wet from gasoline, it will need a thorough clean.

How to clean spark plugs

Lawn mower spark plugs are inexpensive to buy, so you might find it’s easier to simply replace a dirty spark plug rather than cleaning it. Spark plugs are also readily available from hardware stores or online retailers, which means you won’t have to search too hard to find a replacement.

However, if you need to use your mower and can’t get to the store or wait for a new spark plug to be delivered, it’s possible to clean the existing spark plug. Perhaps you also want to avoid buying new parts when it’s not entirely necessary, to help reduce waste and save money. Either way, it’s easy to clean spark plugs in a few simple steps;

Use rubbing alcohol to cut the grease

Dip the tip of the plug in rubbing alcohol to cut through any oily residue. You can also use a brake cleaner or degreaser.

Scrub the spark plug clean using a wire brush.

Rinse with rubbing alcohol or your chosen cleaning product.

Scrub again if required, then dry the spark plug.

If the spark plug is still dirty, repeat the process until clean.

Keep in mind that cleaning the spark plug may not fix it, as the fault may be electrical. If you refit the clean spark plug and the lawn mower engine still won’t start or continues cutting out, you will probably need to replace the spark plug.

How to replace spark plugs

Before replacing your mower’s spark plug, you’ll need to work out which one to buy. Bryan Clayton says, “You need to get a new one that’s the same as your old one. You can write down the code on your old one, check your manual, or take it with you when you go to buy a new one.” As he explains, most spark plugs have a code on the side which makes it simpler to track down the correct replacement. Most manufacturers produce spark plugs that can be used across mower brands, but if you are unsure, consult the owner’s manual.

Whether you have a walk-behind or ride-on mower, fitting a new spark plug should be quick and simple;

Before inserting the new spark plug, apply a very small amount of anti-seize grease (available from hardware stores). This should ensure the spark plug is easier to remove in the future.

Use your fingers to thread the spark plug into place.

For a secure fit, tighten the spark plug another half or three-quarters turn using a spark plug wrench.

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