My Lawn Mower is Not Getting Gas to Spark Plug [5 Fixes that Work]
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It is frustrating when your lawn mower won’t start. I’ve seen this problem even with new gas-powered mowers. After extensive diagnosis and experience, I’ve found the most common cause is that the lawn mower is not getting gas to the spark plug. But that’s not all.
When your lawn mower won’t start, chances are it is not getting gas to the spark plug. Common causes include a dirty air filter, spark plug, and carburetor. To fix these issues, replace the fuel filter, clean the carburetor and spark plug, and replace the fuel if it is old as illustrated below.
What causes my lawn mower not to pump gas to spark plugs?
Gas-powered lawn mowers need gas to be pumped into the carburetor in order to start. Should anything obstruct the flow of gasoline, the engine won’t start. And even if it does, it’s likely to fail after a couple of minutes.
Here’s what causes mowers to not efficiently pump gas to the spark plug and ignite:
A dirty air filter
The air filter on a carburetor cleans the incoming air of dust and other debris that could cause damage to engine parts. Over time, the air filter could get clogged up, thus affecting the flow of oxygen to the engine.
When the engine does not get enough oxygen that helps with fuel combustion when the spark plug ignites your lawn mower won’t start.
Manual choke left turned on
The choke is a shaft-mounted valve within the air intake chamber of the carburetor. Its function is to block the airflow for improved suction and consequently facilitate a more efficient engine start-up.
While some chokes are automatic, some mower motors have manual chokes that the user has to turn on and off by themselves.
If you leave a manual choke on several minutes after starting the mower, the carburetor will likely flood up, leading to starting failures the next time you try to start up your lawn mower.
Clogged filters in the fuel pump
powerful mowers, such as ride-along lawn mowers, make use of fuel pumps to pump gas into the engine – instead of the gravity-feeding system that’s common in most push-along mowers.
If the filters are clogged, your lawn mower won’t start because gas will not reach the spark plug.
Stuck open valves
If the intake and exhaust valves don’t seal fully due to sticking, build-up of debris or normal wear and tear, compression is hampered, consequently creating ignition problems.
If the intake valve becomes stuck, this affects the efficiency of the flow of the air/fuel mixture to the cylinder, resulting in a lawn mower that won’t start.
Signs your lawn mower is not getting gas
There are several issues that could be causing your lawn mower not to run, including electric faults within the spark plugs as well as the causes I’ve listed above.
For instance- if your spark plug is wet, you definitely can’t get your motor to start. However- more often than not- the issue is usually caused by the cutting off of efficient fuel supply to the spark plugs.
Here are a few signs your lawn mower is not getting gas to the spark plug and won’t start due to the inability to pump gas to the engine:
Lawn mower won’t start completely
If you totally can’t get your mower to start, there could be issues with the efficiency of fuel flow to the engine.
- This is usually caused by debris collecting and blocking crucial components of the fuel intake system such as the throttle, primer button, carburetor bowl, and the fuel filter.
- A malfunctioned fuel pump.
Such clogging hampers the efficient flow of gas to the spark plugs.
Riding lawn mower starts then stops running
If your fuel tank is full, but your mower still comes to a stop after just a few seconds, it’s highly likely that the hole atop the tank’s cap has been blocked by dust and debris.
This cuts off the back pressure needed to push fuel out of the tank and into the carburetor – by cutting off air supply into the tank.
No gasoline odor
If you can’t get your mower to start and at the same time can’t sense any gas smell coming from the motor, your lawnmower has definitely run out of fuel.
Most mower brands typically include a dipstick attached to the screw cap. A dipstick is used to check the fuel level within the gas tank. It will typically have low and high-level markers.
- Dip the dipstick into the gas tank to check the gasoline level.
- If the fuel mark is below the low-level mark, it means you’re running out of gasoline and that’s why your mower won’t start.
In this case, refill the gas tank then try starting the mower again to see if the problem will have been fixed.
See also my guide on the type of gas to use with your lawn mower
How to Fix a Lawn Mower that’s Not Getting Gas
Some of these problems can occur when in the middle of mowing. A dirty spark plug, for instance, may cause your lawn mower not to have enough power for mowing. Fuel pump and filter problems too can make it not to start.
Here are simple DIY fixes you can use to correct the problem and start the lawn mower again.
Use fresh or new fuel
I found that for Craftsman mowers, old fuel tends to clog up the carburetors and cause difficulty in the flow of gasoline. As such, you should always ensure that the gasoline in your tank is as fresh as necessary.
- A good way of keeping stored oil fresher for longer is to use a gas stabilization product.
- Use a high-quality fuel stabilizer for small engines such as the Star Tron Enzyme Fuel Treatment.
This solution will prevent fuel degradation by reducing oxidation. Your fuel will stay clean and fresh for longer.
Replace the fuel filter
If you own a Husqvarna mower and it won’t start, the most likely cause would be a clogged fuel filter. This usually happens if you’ve left fuel in your mower for long.
The best fix is to drain off the old fuel from the gas tank and replacing the filter.
Clean the carburetor
For MTD mowers, the most common cause of fuel not getting to the spark plug is a clogged-up carburetor due to the buildup of debris.
To fix the problem, clean up the carburetor by taking out the fuel bowl and spraying the carburetor with some carburetor cleaner.
A clean carburetor will get your MTD lawn mower motor running again.
Here’s a video on how to clean the carburetor on your lawn mower:
Check Change the Oil
For a mower that has been sitting for quite a while, it’s definitely a good idea to check the oil. The best time to change the oil in your mower is about an hour after you finish mowing. But if it has been sitting all winter, check the oil before you even try to start it.
First, check that the oil is good quality, doesn’t have residue in it, and that there is enough of it.
If the oil is very dark or black, it’s time to change the oil so your mower runs smoothly and lasts a long time.
I change the oil in my mower twice a year – once at the beginning of the season, and once just before I put it away for the winter.
If you haven’t done it recently, just give the lawn mower an oil change. Even if this isn’t the primary issue that’s preventing your mower from starting, it’s probably a contributing factor.
Mowers are small engines that don’t require a lot of oil at all. This makes it a pretty inexpensive tune-up to do yourself at home. With a walk-behind mower you’re looking at 10 minutes or less.
Disposing of Your Lawn Mower Oil
Be sure to collect the oil in an appropriate container (I use an empty Gatorade bottle). You want something that caps tight and that won’t spill. I bring it to my local auto shop for disposal.
Your local mechanic or oil change shop will usually take your used motor oil. But if not, there may be disposal programs at your city dump.
If smoke is coming from the mower, that’s another sign that the oil needs to be checked and changed.
A mower that won’t start obviously is not going to smoke. Still, it’s worth mentioning as something worth watching for so you can stay on top of mower maintenance.
A smoking mower could indicate that there is an oil leak somewhere. The leak causes the oil to burn as it comes into contact with hot metal.
It could also indicate that there is not enough oil, which can permanently damage your engine.
Check the Gas Tank, Genius
Have you ever called tech support and the first thing they ask you is if your computer/TV is plugged in?
Gasoline isn’t very stable. If the gas in your mower is more than 30 days old, you’ll need to empty the tank. You may be able to dump the tank by tipping the mower. If not, you will need to siphon it.
After you’re done, put fresh gas into the mower.
The exception to this fix would be if you personally put fuel stabilizer into the gas tank before storing it.
My Recommendation for No-Hassle Gas
Personally I use a product called TruFuel (you can get it at your local box store and most hardware stores carry it). This product is pure, “old school” gasoline without any ethanol added.
You don’t have to add fuel stabilizer, it runs clean, and it can sit in your mower all winter and your mower will start up first pull. I use it in my mower and snowblower and it’s awesome.
It’s expensive compared to regular gas, but it’s cheaper than replacing your mower or buying a new carburetor every few years.
If you do have to siphon out old gas and replace it, remember that mowers take the same gasoline that goes into your car. Rather than trying to dispose of it, you can usually just top off your car’s gas tank. Just make sure that it’s not contaminated gas – if that’s the case then make sure to dispose of it properly according to your municipal guidelines.
Change the Air Filter (it’s easy)
After checking the gas tank and changing the oil, check the air filter on your mower. These can get clogged.
Oxygen is a vital component for combustion in an engine. If your mower’s air filter is dirty your mower won’t run well (or at all).
It is best to replace a clogged filter as opposed to trying to clean it. Even a small perforation in the filter can let in dust or residue that will ruin your engine.
A particularly telling sign of a clogged air filter is if your mower starts but then stops while you are mowing the lawn.
Also, you can look at it. If it’s dirty, you’ll be able to tell because, well, it will look dirty.
Where to Get an Air Filter for Your Mower
Most box stores near you will probably carry the right size air filter for your mower. You can expect to pay around 10 for a new one.
I recommend replacing your air filter annually as part of your regular maintenance.
If you can find the air filter on your mower, then you can replace it. Don’t be intimidated. Replacing the air filter is as simple as removing the old one and placing the new one in its place).
A clogged air filter may not be your only issue. But it’s a good idea to replace your filter when you’re fixing up a lawn mower that won’t start.
Replace Your Mower’s Spark Plug
You will find your mower’s spark plug at the front end of the mower (especially with a walk-behind mower). It is easy to locate because it has a wire that attaches to it. This is usually black rubber and covers the spark plug to keep dirt and debris out.
Make sure that the wire is in good shape and that there is a good connection there.
The next thing to check is the spark plug itself.
You can remove your mower’s spark plug using a socket wrench. You may need to experiment to find the right size. Or you can look it up online. The old spark plug should come out with a few simple twists.
When you remove the spark plug it will be obvious if you need a new one. Look for corrosion or discoloration at the business end of the spark plug. That’s the end that was in the mower (the one with the threads and the small metal piece sticking out). There should not be any corrosion on it.
You can try to clean it up and reconnect it to see if it will work. But, when in doubt just replace the spark plug.
How to Replace a Lawn Mower Spark Plug
Like the air filter, this is not a complicated job. You just need to find the correct socket wrench for your plug and be careful not to over-tighten it when installing the new one.
My advice is to replace your spark plug, even if your spark plug looks relatively new. I replace mine every other year.
In my experience if your mower isn’t starting up after sitting over the winter and you’ve checked the oil and replaced the gas, it’s usually a problem with your spark plug. Parts can often be found at your local hardware store or on Amazon, and a new spark plug is only a few dollars.
Speaking of spark plugs. This is a good time to remind you that it’s always best to disconnect the spark plug if you decide to troubleshoot anything with the lawn mower’s engine.
This is a safety measure to ensure that the engine doesn’t start while you’re working on it. Just unplug the black wire/cable that runs to and covers the end of the spark plug.
Tighten the Mower’s Brake Cable
If the brake cable is loose on your lawn mower, then the mower may not start. To check the tension on the brake, pull the brake handle and then use your hand to pull on the brake cable to see if it is properly tense or if there is any give.
One trick to check to see if this might be your problem is to try starting the mower while you old the brake cable tight. If the mower starts then you’ll know your brake cable needs tightening.
This is usually an easy job. You can complete it quickly with a crescent wrench and a set of vice grips.
What a Dirty, Dirty Carburetor
Issues with the carburetor (or the carb, as it is affectionately known in the biz) are an incredibly common reason for a faulty mower.
After you check the gas, oil, filter, and spark plug, a dirty carburetor is probably the culprit if your mower still won’t start after sitting a long time.
Often, you’ll find that the carb is corroded or that it has clogged if fuel was left in the engine and left to evaporate leaving behind a sticky residue inside the mower’s carburetor.
It’s possible to try cleaning the carb by giving it a good, long soak in a carb cleaner or in vinegar.
If this doesn’t work, carburetors for lawn mowers are not incredibly expensive and they are also relatively easy to find online.
Can I Do This Myself?
Of all the repairs you can tackle, this is the one that people get most intimidated about, but if you’re handy, you can probably find and follow a YouTube video for your model mower that will show you the steps involved.
Are there Other Options?
One work-around if you don’t have the time right away to take your lawn mower engine apart to clean out the carb is to use some starting fluid spray.
A can will just cost a few bucks, and you spray it into the engine right behind where the air filter is (don’t spray it on the air filter). This will typically get your mower running until you have time to get it properly serviced.
Replace Your Fuel Pump?
The fuel pump does exactly what it sounds like … it pumps fuel from the gas tank into the engine via a series of three ports.
If there is too much oil in the engine, then the oil can leak into the fuel pump (specifically into the pulse port line) and make your mower’s fuel pump defective.
To see if the fuel pump isn’t working anymore, check the pulse port line, valves, and the diaphragm inside the pump.
If you’ve tried most of the other potential problems in this article and your mower still won’t start, replace your fuel pump.
Unfortunately it is not possible to repair the fuel pump, it must be replaced. It’s a lot cheaper than buying a new mower, though.
Husqvarna push mower wont start
Spring is here, everything is green, and the grass is growing. but your lawn mower won’t start. No matter how many times you pull, the engine just doesn’t turn over. What do you do?
Your lawn mower needs three things to start:
If you’re having trouble getting your lawn mower started, you’re best bet is to check those three things first. Clogged air or fuel filters, gummed up carburetor needles or floats, and bad spark plugs can mean your lawn mower isn’t going to be ready when you need it.
So before you strain something trying to get it running, here are some troubleshooting tips to help you figure out why your lawn mower won’t start and what you need to do to get it running so you can keep your head above the grass this summer.
Remember to always refer to your operator’s manual first before doing any maintenance.
Why Won’t My Lawn Mower Start?
Old Gas in Your Lawn Mower If you still have gas in your lawn mower from last season, this is the perfect place to begin. About 30 days after being pumped, gas can start to go stale or oxidize, especially if it’s just been sitting in your mower. It becomes less stable and gums up the fuel system as it evaporates. A stuck inlet needle or clogged jets from bad gas can definitely lead to starting problems. Also, ethanol in the gas attracts moisture and causes corrosion. The Outdoor Power Equipment Institute recommends you use gas with 10% ethanol (E10) or less in your small engine equipment. If your mower won’t start, you may need a fresh tank of gas.
Dirty Air Filter Your lawn mower doesn’t run if it can’t get air in the carburetor. Also, a damaged air filter can let in contaminants that can clog or damage the engine. Take a look at the air filter and see if it may be the cause of the problem.
Dirty Spark Plug Your spark plug may be dirty, loose or disconnected entirely, which means you’re not getting any spark. Take a look at the wire and the spark plug itself. Make sure it is dry and clean. If you recently did some maintenance on the mower and disconnected or replaced the spark plug, it’s possible the connection isn’t tight.
What if the starter rope won’t pull?
The crankshaft is connected to the blade shaft on your recoil start walk behind lawn mower, so if the pull cord is stuck, it could be because something is blocking the movement of the blade. Disconnect the spark plug for safety, then take a look under the deck. Clean out any grass or rocks that may be locking up the blade.
If the mower deck housing is clean, here are a few other reasons that might make the pull cord hard to pull:
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How To Clean a Dirty Lawnmower Carburetor
Inspect the Air Filter
The first thing you’ll want to do is to take a look at the air filter. If the air filter is dirty, you can scrape the gunk off, and your carburetor should start working properly again. One common symptom of a dirty air filter is black smoke coming from the exhaust.
Check the Connections
If the air filter is not the culprit, then next move on and check the connections: The connectors between the throttle and choke plates can get sticky when dirty. The screws can also be worn down from the constant vibration. If the screws are too stripped, you might have to replace your carb with a new one.
Clean the Carburetor
If the connectors are not the problem, you will probably have to remove the carb and give it a thorough cleaning. Detach the choke and throttle linkages from the lever and gently slide the carburetor off its mounting bolts. At this point, you might need to unscrew some parts to take the entire carburetor apart. Detach the primer from the base and remove the metering plate and gasket. Now that you have the internal components exposed, take your carb cleaning solution and spray the inside of the ports to clean out any residue. You can also take a soft cloth and give it a thorough wipe-down once you are done.
Examine the Carburetor’s Fuel Bowl
You should check the bowl of the carburetor as well. The fuel bowl contains a small reservoir of gas that feeds the engine to keep it burning. Over time, the fuel bowl will collect stale gas, which will evaporate and form a residue. The fuel bowl is usually located behind the air filter. It has a distinctive bowl shape so you can’t miss it.
Clean Off any Rust
You might also find that your carburetor has some rust built-up. It’s probably a good time to clean off this rust. You can clean it off with some sandpaper to remove the rust.
Reassemble the Carburetor
Once all the components are spic-and-span, you can reassemble the carburetor and reattach it. Ensure that all the diaphragms, gaskets, metering plates, and primer are attached properly before you reattach it back to the engine. If something is off, you might still experience the same problem as your engine starting and sputtering out.
Reattach Everything and Fire Up the Lawnmower
Once the carburetor is reattached, put the fuel line back in and reinstall the air filter housing. Once everything is back together, put some gas in your lawnmower and give it a rip to see if that fixed the issue.
If your lawnmower still has issues due to the carburetor, check to see that all the components have been reconnected properly. If the issue still persists, then you might want to look into getting a new carb to replace your old one.
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How To Stop Your Lawnmower Carburetor From Clogging
The best way to prevent a clogged carburetor is to take it off and clean it relatively frequently. Try to clean your carb once after every couple of uses or after you have left your mower in storage for a while.
You can also prevent clogging by buying a high-quality mower. Briggs and Straton is a well-known brand whose lawnmowers are made of quality components that are resistant to rusting and gumming out from dried-up gasoline.
Lawn Mower Won’t Start? Try These 8 Troubleshooting Tips
Uh oh. It’s finally the day you go to mow your lawn, and your lawn mower won’t start. What now? Before you rush out to buy a new mower or get used to the idea that your lawn is doomed to grow wild forever, try a little troubleshooting. Lawn mowers—whether they’re riding mowers or smaller push models—tend to have the same common problems. Most of the time, there’s an easy solution with an inexpensive fix. Here are some reasons and solutions for a lawn mower that won’t start.
How to Troubleshoot a Lawn Mower That Won’t Start
Once you start looking, you’ll probably find some clues as to why your lawn mower won’t start. Most of the time, you can solve the issue with a simple tune-up costing between 60 to 250.
Check the Gas Tank
If you leave your lawn mower outside or are pulling it out of its winter retirement, you may notice that the fuel has become contaminated with rainwater. To check the fuel tank:
- Examine the fuel level. Is there enough gas in the tank?
- Look to see if there are bubbles of water floating in the fuel (these are usually apparent on the bottom of the tank)
- If you’re still not sure, drain a little bit of fuel and check for water
- If you see signs of water, drain the old fuel completely, dry out the tank using compressed air, and refill it with new fuel
Make sure to detach your spark plugs so your mower can’t accidentally start while you’re checking it over. To prevent this problem in the future, store your lawn mower properly.
Check the Fuel Filter
If fuel isn’t reaching the engine’s combustion chamber during the ignition process, your lawn mower won’t start. Sometimes you can tap the side of the carburetor to push the fuel along. If that doesn’t help, swap out the fuel filter.
Test the Battery
Some lawn mowers (like electric riding mowers) use batteries. Similar to a car battery, it will degrade over time and struggle to hold a charge. You’ll eventually need to replace it, though most batteries last three to five years. If your mower won’t start, check the battery by:
- Looking at the headlights (dim headlights mean your battery is on its way out)
- Visually inspecting the battery for cracks, corrosion, and other damage
- Testing the charge with a device called a multimeter
Check the Oil Level
Lawn mowers need oil just like cars—and that oil can also become contaminated with rainwater. If your lawn mower won’t start, check to make sure you have enough oil. If the oil has turned milky white, it’s a sign that water has contaminated it.
Check the Spark Plugs
Faulty spark plugs are one of the most common reasons a lawn mower won’t start. They can become loose, dirty, disconnected, or worn out. Before reaching for a replacement, clean and tighten the old plugs to see if it fixes the problem. You can usually find them on the back or side of your mower engine.
Clean or Replace the Air Filter
Always check the air filter while troubleshooting. The manufacturer manual should tell you where to locate the filter. If it looks dirty, remove the air filter and try to get rid of some of the buildup. If that doesn’t work, replace it altogether.
Raise the Height of Your Mower
Has your mower ground to a halt? It might be tripped up by too-tall grass. Always adjust your mower height if you’re trudging through patches of tall grass, and make sure to cut grass to the correct height.
Clean the Underside of Your Mower
Sometimes the starter rope on your mower gets stuck or becomes really hard to pull. In this case, it could be an issue with your flywheel break or debris stuck in the underside of your mower. To check for debris:
- Turn off your mower engine
- Disconnect your spark plugs (for safety)
- Examine the blade for debris
- Remove dirt, grass cuttings, and anything else potentially stuck
If that doesn’t fix your problem, your mower may need a more serious repair.
A step-by-step guide to help you grip it and rip it once again
When to Call a Professional
At the end of the day, the reason your lawn mower won’t start could be a problem that you can’t fix on your own. You might need a brand new part (like a starter motor), or you may have to go deep inside the engine to make a repair. These are not the best candidates for a DIY fix.
Mowers have sharp blades. Their construction is highly technical. They’re heavy machinery—especially a riding mower. Attempting to fix issues on your own can be dangerous. The good news is that most homeowners with a small walk-behind mower pay less than 250 to have a professional repair their machine.
If regular troubleshooting didn’t solve your issue, take your lawnmower to a local lawn mower repair shop. You can hire a local lawn care service to mow your grass in the meantime.
FAQ About Lawn Mowers
Why is my lawn mower smoking?
Sometimes dark smoke trailing out of your lawn mower is the result of excess oil. It smokes as it burns off. Other times, it could signal a problem with the combustion or contaminated fuel. If changing the fuel and cleaning your mower doesn’t help, call a professional (especially if the smoke is white).
How can I prevent problems with my lawn mower?
You might notice that problems are more frequent when you pull your lawn mower out of storage. Regularly using and maintaining your lawn mower can help prevent issues. Don’t know where to start? Try these essential lawn mower maintenance tips.
How often should I tune up my lawn mower?
Tune up your lawn mower once a year or every 100 hours of run-time.
Top 8 Reasons Your Electric Start Lawnmower Won’t Start
If your grass needs cutting, and your equipment isn’t cooperating, it could be a quick fix. Here are a few things to check out when operating your electric start lawn mower:
Is the Electric Start Push Key inserted? Make sure the key is fully in.
Is the battery charged? Plug in to charge.
The GFCI May Have Tripped. Reset it by pressing in that little button on the outlet until it clicks.
The circuit breaker may have tripped. Make sure the gas lawn mower’s engine is stopped, remove the Electric Start Key and disconnect spark plug boot. Then check around the blade and clear any debris that may be blocking it. Reattach the spark plug boot and reinsert key. Wait 30 seconds so the breaker can self-reset, then try restarting.
The engine may be flooded. Wait a few minutes before trying to start up again.
Fresh fuel in the tank? If it’s empty or the fuel’s stale, fill ‘er up with fresh fuel.
Is the blade control engaged? If not, depress the blade control and try starting again.
Spark plug issues? Remove spark plug and check to see if it’s fouled, blackened or damaged. Clean, adjust or replace as necessary.
Have a different issue with your Remington lawn mower? Check out the Troubleshooting section in your model’s manual.