There are a number of reasons, mechanical and otherwise, why a mower won’t run. The good news is that fixing most all of the issues is easy enough for a DIYer to handle.
By Tony Carrick and Manasa Reddigari | Updated Aug 8, 2022 4:03 PM
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Lawn care can be tedious, but once the grass starts growing in the spring, mowing becomes a fact of life in most neighborhoods. When you finally muster the strength to tackle that first cut of the season, there are few sounds as disheartening as that of a lawn mower engine that turns over but doesn’t start.
Before you drag the mower in for repairs or invest in costly replacement parts, first make sure that a clogged air filter, soiled spark plug, damaged safety cable, clogged mowing deck, or contaminated gas isn’t to blame. Work through the following steps, and you may be able to get your puttering grass guzzler up and running again in no time.
A lawn mower repair professional can help. Get free, no-commitment repair estimates from pros near you.
Change the lawn mower carburetor filter.
Your lawn mower’s air filter guards the carburetor and engine from debris like grass clippings and dirt. When the air filter becomes clogged or too dirty, it can prevent the engine from starting. To keep this from happening, replace paper filters—or clean or replace foam filters—after every 25 hours of engine use.
The process for removing the filter depends on whether you are operating a riding or walk-behind lawn mower. For a riding mower, turn off the engine and engage the parking brake; for a walk-behind mower, pull the spark plug wire from the plug. Then, lift the filter from its housing.
The only choice for paper filters is replacement. If you’re cleaning a foam filter, wash it in a solution of hot water and detergent to loosen grime. Allow it to dry completely, and then wipe fresh motor oil over the filter, replace it in its housing, and power up the mower—this time to the pleasant whirring of an engine in tip-top condition.
Check the spark plug.
Is your lawn mower still being stubborn? The culprit may be the spark plug, which is responsible for creating the spark that ignites the fuel in the engine. If it’s loosened, disconnected, or coated in water or carbon residue, the spark plug may be the cause of your machine’s malfunction.
Locate the spark plug, often found on the front of the mower, and disconnect the spark plug wire, revealing the plug beneath. Use a socket wrench to unscrew the spark plug and remove it.
Check the electrode and insulator. If you see buildup, spray brake cleaner onto the plug, and let it soak for several minutes before wiping it with a clean cloth. Reinstall the spark plug, first by hand, and then with a socket wrench for a final tightening. If the problem persists, consider changing the spark plug.
Clear the mower deck of debris.
The mower’s deck prevents grass clippings from showering into the air like confetti, but it also creates a place for them to collect. Grass clippings can clog the mower deck, especially while mowing a wet lawn, preventing the blade from turning.
If the starter rope seems stuck or is difficult to pull, then it’s probably due to a clogged deck. With the mower safely turned off, tip it over onto its side and examine the underbelly. If there are large clumps of cut grass caught between the blade and deck, use a trowel to scrape these clippings free. When the deck is clean again, set the mower back on its feet and start it up.
Clear the vent in the lawn mower fuel cap.
The mower started just fine, you’ve made the first few passes, then all of a sudden the mower quits. You pull the cord a few times, but the engine just sputters and dies. What’s happening? It could have something to do with the fuel cap. Most mowers have a vented fuel cap. This vent is intended to release pressure, allowing fuel to flow from the tank to the carburetor. Without the vent, the gas fumes inside the tank begin to build up, creating a vacuum that eventually becomes so strong that it stops the flow of fuel.
To find out if this is the problem, remove the gas cap to break the vacuum, then reattach it. The mower should start right up. But if the lawn mower won’t stay running and cuts off again after 10 minutes or so, you’ll need to get a new gas cap.
Clean and refill the lawn mower fuel tank.
An obvious—and often overlooked—reason your mower may not be starting is that the tank is empty or contains gas that is either old or contaminated with excess moisture and dirt. If your gas is more than a month old, use an oil siphon pump to drain it from the tank.
(It’s important to be careful as spilled oil can cause smoking, but there are other reasons this might happen. Read more about what to do when your lawn mower is smoking.)
Add fuel stabilizer to the tank.
Fill the tank with fresh fuel and a fuel stabilizer to extend the life of the gas and prevent future buildup. A clogged fuel filter is another possible reason for a lawn mower not to start. When the filter is clogged, the engine can’t access the gas that makes the system go. If your mower has a fuel filter (not all do), check to make sure it’s functioning properly.
First, remove the fuel line at the carburetor. Gas should flow out. If it doesn’t, confirm that the fuel shutoff valve isn’t accidentally closed. Then remove the fuel line that’s ahead of the fuel filter inlet. If gas runs out freely, there’s a problem with the fuel filter. Consult your owner’s manual for instructions on replacing the filter and reassembling the mower.
Inspect the safety release mechanism cable.
Your lawn mower’s reluctance to start may have nothing to do with the engine at all but rather with one of the mower’s safety features: the dead man’s control. This colorfully named safety bar must be held in place by the operator for the engine to start or run. When the bar is released, the engine stops. While this mechanism cuts down on the likelihood of horrific lawn mower accidents, it also can be the reason the mower won’t start.
The safety bar of a dead man’s control is attached to a metal cable that connects to the engine’s ignition coil, which is responsible for sending current to the spark plug. If your lawn mower’s engine won’t start, check to see if that cable is damaged or broken. If it is, you’ll need to replace it before the mower will start.
Fortunately, replacing a broken control cable is an easy job. You may, however, have to wait a few days to get the part. Jot down the serial number of your lawn mower, then head to the manufacturer’s website to order a new cable.
Check to see if the flywheel brake is fully engaged.
The flywheel helps to make the engine work smoothly through inertia. When it isn’t working properly, it will prevent the mower’s engine from working.
If it is fully engaged, it can make a mower’s pull cord hard to pull. Check the brake pad to see if it makes full contact with the flywheel and that there isn’t anything jamming the blade so the control lever can move freely.
If the flywheel brake’s key sheared, the mower may have run over something that got tangled in the blade. It is possible to replace a flywheel key, but it does require taking apart the mower.
Look out for signs that the mower needs professional repairs.
While repairing lawn mowers can be a DIY job, there are times when it can be best to ask a professional to help repair a lawn mower. If you’ve done all of the proper mower maintenance that is recommended by the manufacturer, and gone through all of the possible ways to fix the mower from the steps above, then it may be best to call a pro. Here are a few signs that indicate when a pro’s help is a good idea.
- You see black smoke. The engine will benefit from a technician’s evaluation, as it could be cracked or something else might be worn out.
- Excessive oil or gas usage. If you’ve changed the spark plugs, and done all of the other maintenance tasks, and the mower is consuming more than its usual amount of oil or gas, consult a professional for an evaluation.
- The lawn mower is making a knocking sound. When a lawn mower starts making a knocking sound, something could be bent or out of alignment. It may be tough to figure this out on your own, so a pro could help.
- A vibrating or shaking lawn mower can be a sign of a problem beyond a DIY fix. Usually something is loose or not aligning properly.
How to Repair a Lawn Mower Pull Cord
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Replace a broken starter rope on your lawn mower quickly and easily by following this simple step-by-step procedure.
You tug one last time to get the lawn mower started, and suddenly the pull cord breaks and the end goes spinning into the hole. Don’t blow a gasket. If you have even a tinge of mechanical aptitude, replacing a starter rope is pretty easy. If the spring breaks—a rare event, according to our repair expert—the fix is a lot harder, and we recommend you take the mower to a repair center.
Stuck Cord or Broken Cord?
First, check to confirm that the cord is actually broken and not just stuck. If it’s stuck, it may be an easier fix than full pull cord replacement and you likely won’t have to buy any new parts. Here are a few tips for fixing an electrical cord.
Run through your troubleshooting checklist if your cord isn’t working. Check to ensure the brake is off, make sure there isn’t any lawn debris clogging the blade, and finally, if all else fails, use our steps below to open the rewind unit. There, you’ll be able to see if the cord is stuck or fully broken.
What to Know About Replacement Cords
Different lawn mowers need different types of pull cords. If you don’t have time to spend looking for the right match, you can opt to get the thinnest kind, which will fit no matter what. But the thinner the cord, the more likely it is to break again soon. If you don’t already have replacement cord on hand, go to your local hardware store with the broken cord. The associates there should be able to help you get the exact kind you need.
Lawn Mower Parts
Search and shop all the parts you need for your riding lawn equipment and Gator UTV including lawn mower blades, filters, belts, spark plugs, oil, and home maintenance kits.
Search part numbers and John Deere parts diagrams to identify exactly what you need to keep your equipment running smoothly.
Quick Reference Guides
As a John Deere owner, when it’s time to maintain, service or repair your equipment we have easy-to-use information sheets that keep your John Deere equipment running well.
Home Maintenance Kits
Feel confident in tuning up your lawn mower or garden equipment this season with our Home Maintenance Kits. Easily find the right product so you can DIY and save!
Looking for your Serial Number?
Finding your lawn mower’s model number and serial number is as easy as locating the identification tag on your machine. As seen in the example, the model number will be displayed below the MODEL heading (Example: Z235), and the serial number will be underlined on the top-right corner of the tag (Example: 130002).
If you’re looking for the engine number, that can be found directly on the engine itself.
Home and Garden, eat your heart out.
Get the latest on how to care for and enjoy your yard and garden. The articles and videos are informative and the ideas are amazing.
MowerPlus Mobile App
MowerPlus is the app you need to keep your John Deere riding lawn mower running well and your lawn looking great this season. The app tracks and records yard tasks and serves as a one-stop shop for seasonal care tips and maintenance activities. Know your mower and know how you mow with John Deere’s MowerPlus app.
Easiest Things To Check On A Lawn Mower If The Starter Rope Is Stuck
The Right Part. The Right Price.
At John Deere, you get the value of choice for your maintenance and replacement parts for all makes and ages of machines – at any budget.
Genuine John Deere Belts Blades are your best choice for your newer machines.
Alternative Parts are an economical solution for your John Deere equipment.
The John Deere Easy Change™ 30-Second Oil Change System
Never drain engine oil again.
We’ve changed the oil change. Revolutionized it really. See how fast and easy changing your oil can now be on 100 Series Riding Lawn Tractors with the John Deere Easy Change™ 30-Second Oil Change System. Only from John Deere. Included on the E120, E130, E150, E160, E170, and E180 models.
Step One. Take it off.
Lift the hood. Make sure the engine is cool, then, twist to remove. It’s that simple.
Step Two. Twist and lock.
Grab the new Easy Change™ Canister, twist and lock into place. Make sure the arrow on your Filter System aligns with the arrow on your engine.
Step three. Done.
Close the hood and mow. John Deere recommends the Easy Change™ 30-second Oil Change System every 50 hours or at the end of your mowing season. Don’t drain engine oil ever again.
Draining engine oil is so 2017.
The engine modifications and new technologies are in. The re-envisioned oil filter with a media designed to resist breaking down in oil over time is here. The thousands of hours of testing are done. The end result is an all-in-one, oil and oil filter system like no other. The first of its kind. And thanks to the new John Deere Easy Change™ 30-Second Oil Change System (“System”), you’ll never have to drain the oil from 100 Series Riding Lawn Tractors again.
Here’s why: The new System captures contaminants and recharges your engine with nearly a quart (0.8qt) (0.76 l) of new oil. In fact, this System increases the amount of oil in the engine by nearly 40%. 2 Your engine likes that.
What do you mean, I will never have to drain oil from my engine again? How is that possible? The answer is simple. We have developed a better filtration system and filter design for our 100 Series Riding Lawn Tractors 1. This fully synthetic filter media has greater surface area which increases its capacity to hold harmful contaminants. What’s more, the filter media is designed to resist breaking down in oil over time. Which means you’ll get a cooler running engine. And a cooler running engine and better filtering helps increase engine oil life. John Deere’s recommended oil service for 100 Series Riding Lawn Tractors 1. is to change the System every 50 hours or once a season, whichever comes first. Remember, the System replaces a portion of your engine oil. And that’s plenty.
The System uses John Deere Turf-Gard™ Oil. Using John Deere Turf-Gard™ Oil ensures you are using the exact oil specified by John Deere engineers.
Testing. Testing. Testing. Thanks to thousands of hours of rigorous and extensive testing, you can feel confident your engine will run for years to come.
1 The John Deere Easy Change™ 30-Second Oil Change System is available on E120, E130, E150, E160, E170 and E180 Lawn Tractors today.
2 Compared to similar V-Twin engine models that do not have the John Deere Easy Change™ 30-Second Oil Change System. That includes equivalent Deere 2017 models and 2018 models without the System.
Frequently Asked Questions:
What is new with John Deere Riding Lawn Equipment?
We are excited about the exclusive John Deere Easy Change™ 30 second oil change system. Exclusive to John Deere and only available on certain models of the new 100 Series Lawn Tractors. These tractors are designed for ease of use for both operation and maintenance. The John Deere Easy Change™ System (“Easy Change”) allows the user to easily complete the recommended engine oil and filter maintenance in 30 seconds.
What is this new oil change system?
We changed the oil change. The all-in-one oil and oil filter system gives the owner the ability to change a portion of the oil and the filter in less than 30 seconds.
What happens to the rest of the oil in the engine when the Easy Change system is replaced?
The Easy Change system replaces.8 quart of oil. The remaining oil in the engine is refreshed by the charge of new oil included in the replacement Easy Change system. Combined with 40% more engine oil capacity, improved filtration and cooler running temperatures which help extend oil life, it is no longer necessary to remove and dispose of all the oil in your engine during service.
What makes the Easy Change system unique from other filters?
It is not just a filter. It is a newly developed technology system that allows a new “filter” to come already charged with oil and allows you to remove an existing filter and the contaminants inside without tools and without making a mess. Beyond the filter, technology within the canister and on your engine makes this possible.
Models with the Easy Change oil system use a fully synthetic filter that has more capacity to trap and hold contaminants. The larger surface area of the Easy Change canister acts like a radiator helping the oil to stay cool.
Does the Easy Change system somehow decrease the life of the engine?
The John Deere 100 Series lawn tractor models, with and without Easy Change, are specified for the same lifetime and are rigorously tested to the same standards to ensure the life of the tractor meets expectations.
Can I add the Easy change system to an existing tractor?
Because this system also requires unique features within the engine, the Easy Change system cannot be added to an engine that was not equipped with it at the factory.
Can I change all the oil if I choose to?
You could if you wanted to. There is an oil drain plug. It is not required for maintenance.
How often do I need to change the Easy Change canister?
Every 50 hours or once a year. The 100 Series Lawn Tractors with and without the Easy Change system have the same maintenance schedule.
What type of oil is recommended?
We recommend only John Deere Turf-Gard™ 10W30 Oil. The Easy Change canister comes pre-filled with John Deere Turf-Gard™ 10W30 oil.
How do I recycle the old oil?
Many local government recycling programs, authorized retailers, auto repair stations, and auto parts stores will puncture and recycle used oil filters and oil.
Do I ever need to add oil?
Yes. Consistent with our service recommendations for this product, you should check oil level daily and add oil if required.
Lawn Mower Pull Cord Won’t Retract
You’ve just finished cutting the grass with your trusty lawnmower when you walk over to start it up again and pull on the starter cord, but nothing happens. What should you do?
When your lawn mower pull cord won’t retract, it may be due to a broken or jammed assembly, rusted ball bearings, and a damaged starter clutch or recoil mechanism. Easy fixes include replacing the broken, rusted, or damaged parts. Also, lubricating the moving parts may help solve these problems.
Read on to learn more about the problems that may cause your lawn mower’s pull cord to not retract, and easy fixes that may help.
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The Pull Cord Assembly Is Broken or Jammed
If the lawnmower pull cord is broken or jammed, it will not retract. In general, the pull cord assembly may do the following:
- Break or get jammed due to a bent or broken pulley.
- Have a bent or broken cord.
- A slipped knot in the cord jams when the end comes through the hole in the housing.
- Rust/corrosion from exposure to weather affecting metal components.
Here are some tell-tale signs of a broken or jammed pull cord assembly:
- The pull cord is broken, or the pull cord is hanging loose but is not attached to any part of the mower.
- The pulley does not rotate when you pull on the starter cord.
- The starter grip rotates with the pulley, but no cord moves through it because there’s an obstruction in the housing, such as something blocking the passage of the cord.
- The engine starts fine but stops running as soon as you release the handle or stop pulling on the cord.
How To Fix
To fix a broken pull cord, replace it with another similar-sized sturdy rope or leather cord. Make sure to knot it securely at both ends. If the pulley is bent or otherwise damaged, replace it. Have a professional repair any stripped teeth on the engine flywheel or replace it if necessary.
You could also disassemble the starter housing as far as needed to access what needs to be repaired or replaced.
As for corroded ball bearings, spray them with lubricating oil (WD-40 works well) and then work the pull cord until they loosen up again; otherwise, replace them entirely.
The Ball Bearings Have Rusted
If the ball bearings have rusted due to exposure to weather affecting metal components, the lawnmower pull cord won’t retract because the ball bearings in the starter clutch are frozen or rusted.
Here are five signs that your lawn mower’s ball bearings are rusted:
- The starter cord doesn’t fully retract when you release it.
- The starter cord pulls out slowly and reluctantly, even when you’re just trying to roll the mower around in place.
- There’s a noticeable clicking or popping sound every time you pull the starter cord and try to start the engine.
- You can hear and feel a gritty rustling noise coming from inside the lawn mower housing when you try to retract the starter cord by hand.
- When you pull up on the starter cord, it barely moves at all. Or if it does move, then it moves only slightly but requires great effort.
How To Fix
For starters, try spraying them with lubricating oil, such as this highly effective, easy-to-apply, and moisture-displacing WD-40 Multi-Use Product with Smart STRAW (link to Amazon), and then working the pull cord until they free up again.
Also, you can try cleaning the rust/corrosion off of the ball bearings with steel wool or sandpaper to give them a fresh start. If these solutions don’t work, replace them entirely. As for the started clutch–check it for damage and replace it as necessary.
EASY! HOW TO FIX a Briggs and Stratton lawnmower STARTER PULL ROPE
Additionally, ensure you always clean your mower to keep it in the best shape. Here’s a video that may help:
Thriving Yard aims to simplify the unnecessarily complex process of growing and maintaining a healthy, thriving lawn and garden. Unlike corporate website companies who write articles from an office overlooking a major city, the authors on this website live in small towns and regularly use many of the tips and recommendations provided in their own garden and lawn care. Read