Troubleshooting When Your Lawn Mower Will Not Start
You’re all set to mow the lawn, but when you go to start your machine, nothing happens. There could be several reasons why your lawn mower will not start, including something as simple as skipping a step in the starting process. Plus, depending on whether you have a walk-behind or riding lawn mower that won’t start, you could have a different root cause for the same problem. Here are some troubleshooting tips to find out what went wrong, what lawn mower parts you need to fix it, and if you’ll need to take your lawn mower in for professional service.
Check the startup process in your operator’s manual
It seems simple, but sometimes you just forgot a step in the process. Before doing anything else, download the MTD operator’s manual for your model and go through the steps to start your mower up again. You may need to engage the control handle, connect the spark plug wire, check the battery, and activate the choke and parking brake if you have a riding lawn mower. If your lawn mower still will not start, move on to the next step below. Keep that operator’s manual close by as you will use it to identify any replacement lawn mower parts you need.
If your walk-behind or riding lawn mower won’t start, the culprit may be old fuel. Stale fuel that’s more than 30 days old and has not been modified with stabilizer will not combust and your engine will not start. Siphon or drain the old fuel from your mower, dispose of it properly and replace it with fresh fuel. If you’re unsure whether or not the fuel is stale, you can test it with Fuel Defense(TM) test swabs, which you can order online from MTD Parts.
In addition to failing to combust, old fuel that has been stored in your mower without stabilizer for an extended period of time will begin to leave deposits as it breaks down. Your engine, lines and carburetor can become gummed up or blocked by the old fuel deposits. You’ll need to take your machine in for professional lawn mower service if your carburetor is gummed up or damaged by old fuel.
Find out if fuel deposits are the reason your lawn mower will not start by removing the spark plugs. If you don’t smell fuel in the combustion chamber or on the spark plugs, you probably have blocked fuel lines. Use a spray carburetor cleaner or pressurized air to try to clear things out.
To avoid the hassles that come with old fuel, use an additive like StaBil in your gasoline and change out the old fuel at the end of the season.
After a few years your spark plugs will have accumulated too much dirt and deposits to function properly, and the buildup on the electrodes can prevent a spark. If the damage or buildup is not too bad, you may be able to clean the plug. Otherwise, if it has become corroded beyond repair you’ll need to replace it. You may also simply have a problem with the gap between your spark plugs. Check your operator’s manual for the proper distance and adjust it.
When you mow, dirt and debris gets sucked up into your machine. That’s why there’s an air filter on it. But if your filter has become full and dirty, the debris may also work its way into the engine and your lawn mower will not start. Clean or replace the dirty air filter and change out the contaminated fuel. If you have a push or walk-behind mower, you want to be careful when changing out the fuel not to tip the mower on its air filter side as this can cause oil to leak into and clog the filter.
Lawn mower won’t start? Try replacing the air filter with a genuine MTD Parts air cleaner kit.
Take your lawn mower to an MTD service center
If none of the above tactics work, you can check out our tool to diagnose and troubleshoot your mower or take it in for lawn mower maintenance at a local service dealer. One of the last possible reasons for a lawn mower that will not start is a failed engine ignition coil. It’s rare and you’ll need to test for electrical activity with a spark plug circuit-testing tool. This lets you safely check the flow of the electrical current from the ignition coil to the spark plug terminal. If there’s no electric activity, you’ll need to take it to a professional for inspection and repair.
Order the lawn mower parts you need from MTD Parts
Once you diagnose why your walk-behind or riding lawn mower won’t start you can order the proper MTD lawn mower parts you need to make repairs. Use your operator’s manual and our Parts Finder to get what you need. Of course, it’s always wise to have a few items on hand to make quick repairs when necessary. Consider keeping these in stock from the start of the season:
You may also want to find a local MTD service dealer so you can bring your lawn mower in for maintenance when a repair is outside your area of expertise.
Briggs and Stratton 5hp wont start, senior help needed!!
It is strange. I got this mower as it was not running very well. Poor performance, rpms humming, suddenly just dying etc. Backfiting through exhaust and carburetor.
Now it doesnt start up anymore at all. With choke on it at least coughs and backfires. Without choke, nothing. Until i spray starter fluid directly to intake or spark plug.
Conclusion
Briggs and Stratton’s lawnmowers are the gold standard for affordable mowers. These engines are also regularly used in other brands of lawnmowers. Being widely sold in so many countries means that spare parts and repair facilities are widely available.
Treating your Briggs and Stratton lawnmower with a bit of care and undertaking annual preventative maintenance will hopefully ensure many years of reliable service.
Lawn Mower Won’t Start Fixes
You’ve just taken your lawnmower out of your garage, and when it’s time to start mowing the lawn, it won’t start. It’s a common problem to have, but there’s often a quick and easy fix if you can diagnose the problem. Some of the most common reasons a lawn mower won’t start include low fuel, spark plug issues, a clogged carburetor, a broken clutch, or broken gears.
Five Reasons Your Lawn Mower Won’t Start
Low Fuel
A common reason why a lawn mower won’t start is low fuel. While that might sound a bit too obvious, low fuel could be the reason your lawn mower won’t start, especially if you had previously used your mower for an extended period without refueling. In some cases, it might be that your tank has old fuel. Old gasoline loses its potency, so it won’t be able to combust. The result is that your engine won’t start. So the first thing you should do is make sure you have enough fuel and that it is not too old.
Bad Spark Plugs
A bad spark plug is another common reason why your lawn mower won’t start. The spark plug is the component of your engine that creates the spark which ignites the gasoline. If you have the user manual, look up where the spark plugs are located. Make sure you handle the spark plugs carefully. You can buy a special solution from a hardware store to clean your spark plug from any moisture or grease. After doing that, try to start the lawnmower again. If that did not fix the problem, then you might need to buy a new spark plug. Make sure that you find one that is compatible with the type of engine that you have. Or else it will not work and could cause more damage. Your user manual should specify which kinds of plugs are compatible with your mower.
Clogged Carburetor
Another common issue that can cause a lawn mower to not start or to start and then die is a clogged carburetor. If your carburetor is dirty your lawnmower might start then die, or it might not start up at all. The carburetor mixes the fuel with air so that it can combust properly. If your engine does not get the right fuel/air mixture, then it cannot ignite, and your mower will not work. So we recommend checking the filter in your carburetor. The most common culprit is the air filter. Leftover gas can condense and solidify in the filter so it is unable to pull in air. If the air filter is dirty, then the carburetor will not be able to draw air into the engine. It could also be that your carburetor is not attached properly and is not sealed, so air is leaking out after it is drawn in.
Broken Clutch
If your lawnmower starts but the blades are not working, then the problem could be your clutch. The clutch is the thing that diverts power from the engine to drive the blades. Without a working clutch, you won’t be able to work the blades properly. You can repair the clutch yourself or you can get a professional to help. Unless you have previous experience working with lawnmowers, we would recommend getting a professional to fix it up and install a new piece.
Broken Gears
Broken gears can also be the cause of your lawn mower not starting, but this isn’t that common. If you have checked all the other issues on this list but have had no luck, then the next thing to check is the gears. If your mower motor is rotating, but the engine is not working, then it could be a problem with bad gears. You can tell if the gears are busted if there is a slow response from the operating button. If your gears are the culprit, then we recommend getting a professional’s help to fix them. You can do this on your own, but we would not recommend that unless you have previous experience fixing lawnmowers.
hash-mark
If it has been a long time since you last used your mower, it might take a bit to warm them up. Most of the time, when you store a lawnmower for a long time, moisture will build up in the fuel tank. Water in the tank dilutes the fuel and can also make the spark plugs not work properly. So if you are just using your lawnmower after a long hiatus, we recommend taking out the fuel tank and trying to get rid of any excess moisture in it.
Why Is My Lawnmower Turning Over But Not Starting?
If you pull the cord and hear your engine turn over, but your mower is not starting, the most common reasons for this are low fuel, a broken gas valve, or a bad choke fault. A broker spark plug could also be the culprit. You may also have to change the fuel pump if it does not get fuel to the ignition system.
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.
My Lawn Mower is Not Getting Gas to Spark Plug [5 Fixes that Work]
Affiliate Disclaimer: My content may contain links to products I use and love. As an Amazon Associate and participant in various other affiliate programs, I earn a small commission at no extra cost to you from qualifying purchases. I only recommend products I personally vetted!
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.
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: