Troubleshooting lawn mower problems. Here s Why Your Lawn Mower Won t Start And What To Do About It

How To Troubleshoot a Lawn Mower That Isn’t Turning Over

Have you ever encountered a situation where your lawn mower won’t turn over or fails to do that even after several tries? If yes, it must have kept you thinking about whether it is possible to troubleshoot this problem or how to troubleshoot a lawn mower that doesn’t turn over.

Firstly, gather up all the required tools and materials. Then, inspect the current state of the spark plugs, spark plug lead, battery, solenoid, and starter thoroughly. Clean, repair or replace the faulty or damaged internal elements. Next, check whether the engine is seized up and manually push the blades to unseize it.

Keep reading this following article and learn the detailed way of troubleshooting a lawn mower not turning over.

Steps to troubleshoot a lawn mower not turning over:

Imagine you are about to start your work, and out of the blue, you figure out that your lawn mower not turning over.

If you have no recollection of what might have gone wrong or cannot pinpoint the reason behind such commotion, you can start by checking the basic areas and applying simple fixing tricks.

Sometimes, people only think of bigger issues and overlook the simple minor faults that can lead us to experience such troubles.

But if minor fixes can save your time and money, why would you want to invest in professional servicing for minor fixings.

That’s why I have decided to present a quick, easy, and cost-effective DIY method of troubleshooting a lawn mower that does not turn over.

Things required to troubleshoot the lawn mower not turning over:

Have a proper glance at the checklist of the required tools and materials:

Step 1- Check the Spark plugs Spark plug lead:

As soon as you encounter such troubles, you should make sure that the spark plugs and the plug lead are in good working condition.

First, you should check whether the spark plugs are operating properly or defected because the mower won’t turn over with a defective spark plug on it.

To inspect, disconnect the lead and clean the surrounding area. Then, use a socket to remove the plug.

Next, if the plug looks dirty, clean it with a wire brush and a spark plug cleaner. Then reinsert it again and ensure it fits into the position securely.

If the spark plug looks damaged, cracked, or broken, you should replace it.

After that, you should inspect the spark plug lead with a spark plug tester or multimeter.

Connect one tester prong to the spark plug lead and the other end to the spark plug. Then, try to start the engine and verify the result with your mower’s user manual. If required, replace the spark plug lead.

Step 2- Check the Battery, Solenoid Starter:

While checking the spark plugs and plug lead’s state, do not forget to inspect the condition of the battery and solenoid.

Follow the step-by-step instruction provided in this video to troubleshoot your mower battery thoroughly.

Watch this DIY video to test the solenoid’s condition.

Besides that, you should also test the starter to confirm whether the starter is the main culprit of your lawn mower’s turnover failure or not.

To troubleshoot your lawn mower starter easily and thoroughly, without skipping a single step follow this video.

Step 3- Manually pushing the Engine Blades:

In case you are experiencing the same issue of hearing only clicks whenever you turn the key, it’s most probably the engine is causing such trouble by being seized up.

Thus, manually just push on it to get the engine to turn over, but do not push it too hard because it’s plastic.

First, take this cover off and you will see four screws here.

Then, take off those screws too.

Now, try to push it with your fingers to make sure the motors are free and bound up.

Check whether the mower is starting over or turning over now and if none of the above fixing tricks work for your mower, be sure to contact the nearest service provider for professional assistance.

Performing such repairing tasks can be hazardous. Thus, make sure you have enough knowledge and expertise to perform them. Remember to first read your mower’s instructions manual before operating, servicing, or troubleshooting it.

Frequently Asked Questions

What causes my riding lawn mower not to crank?

There can be various reasons behind a riding lawn mower starting trouble or failure, such as stale gas, ignition switch malfunctioning, a bad battery, or failed alternator.

How to determine if my lawn mower spark plug is bad?

Remember, the more worn out or dirty the spark plugs are, the greater the tug on the rewind, and you will need more effort to produce an adequate spark.

Thus, if you notice that your lawn mower won’t start or the lawn mower engine requires a constant tug on the rewind to start, you most probably have a damaged or broken spark plug in your lawn mower ignition system.

Is it possible to unseize a lawn mower engine?

The easiest way to unseize your lawn mower engine is to turn the internal blades manually using your hand.

To do this, put on the safety gloves and hold or clamp down the blade activation lever on the handle. Then, try to push the blades.

Where should I spray starter fluid in my riding mower?

Spray a light quantity of starter fluid directly into your lawn mower’s carburetor chamber.

You can also spray the starter fluid into the intake near the air filter or the engine’s spark plug bore.

How to determine if the starter solenoid on my riding mower is bad?

The most common sign or symptoms of a bad starter solenoid are engine starting struggle, no cracking, no clicking sound while the engine starts, the starter tends to spin without engaging the Flywheel fully, or the engine cranks slowly.

Final Verdict

Lawn mowers won’t turn over trouble is not a new thing among the mower user community, and sometimes, easy DIY fixing techniques can save both your time and money.

Initially, the entire troubleshooting process might seem a bit complicated, but if you follow all the instructions given in today’s article, you can fix the problem easily and quickly.

Remember, you can only get the best outcome if you thoroughly follow all the instructions to troubleshoot a lawn mower not turning over.

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Here’s Why Your Lawn Mower Won’t Start And What To Do About It

Standing in your garage with a dead lawn mower, a phone browser open to Google, and the vast untamed landscape of small engine troubleshooting before you, it can be easy to get discouraged. After all, just about anything that prevents a lawn mower from running well can also prevent it from starting. Let’s simplify all these possibilities and zero in on common starting problems, and ones that you’re likely encountering.

Of course, your situation could include all manner of devices thought of as mowers. You could have a simple push mower, or maybe an electric start push mower. But, you could also have a riding mower, an electric mower, or a zero-turn mower that costs more than a Chevrolet Spark. You might even have a tractor towing a rotary cutter like a Bush Hog, in which case you’re probably not reading this article. We’re going to take a look at the most common: push mowers and riding mowers. Your electric mower is essentially always started, and your licensing agreement might prohibit your working on your own tractor. We also won’t deal with zero-turn mowers directly, but obviously a lot of the info for small engines in general will apply to zero-turns. Let’s dive into some of the reasons your mower may not be starting, and what you should do about it.

Ignition system problems: spark plugs

At some point — possibly when the words we have ignition from the Kennedy Space Center Firing Room — many of us began to think of the word ignition as synonymous with starting, but that’s not exactly what’s going on with ignition systems. An ignition system is actually about producing a spark that ignites a fuel-air mixture within an engine’s cylinder(s). Ignition happens continually when you’re using a mower. A few components of this system can be culprits when an engine won’t start.

The most common culprit is probably a spark plug that needs cleaning or replacement. Buildup from a constantly exploding engine cylinder will eventually degrade the performance of the plug until it can’t function properly at all. It’s a little easier to diagnose a bad spark plug in an engine that will barely start than one that won’t start at all, and if you’ve recently noticed that your mower makes you pull the starter rope harder, is prone to losing power while running, or starts using more gas than normal, the plug might be the problem. The clearest sign of plug trouble is when your engine will turn over but not actually start.

It’s a good idea to replace them at least once per year, and cleaning or replacing your plugs is a reasonable first step in resolving just about any starting problem. You can try gently cleaning a spark plug with fine-grit sandpaper, a file, or a soft wire brush, and you can use carburetor or plug cleaning spray to help. Just be gentle; damaged plugs will not be kind to your engine. There are other potential plug issues (wrong plug, bad gapping, or a cracked insulator) that might not be worth diagnosing, given that replacing the plug with a new (and correct) one addresses all these issues at once.

Ignition system problems: plug wires and coil

After dealing with the plug, it’s just about time to get serious with your diagnostics. But first, inspect your plug wires for obvious wear or damage. If they appear to be in poor shape, they probably are, which makes replacing them a good idea regardless of whether they are the full cause of your starting troubles. Next, it’s time to verify that your engine isn’t getting a spark. Ground your plug’s threads against a metal part of the engine itself and have someone attempt to start the mower as you observe the plug. If you consistently don’t see a spark, you should start looking at other possible causes.

If your plug wires are in good shape, ensure they’re making good contact with the spark plugs. Clean their terminals and, if necessary, squeeze the terminals slightly with pliers. If your mower has an on/off switch, use an electrical tester to make sure it’s functioning. Switches on mowers with pull cords can be slightly tricky to diagnose, so it might be a good idea to check the on/off function with a multimeter set to continuity mode. The point is that the continuity should change when the switch changes from on to off; some switches might close a circuit when on while others might open the circuit, but there should definitely be a change when the switch, well, switches. Check that the coil control wire connecting the engine to the coil isn’t abraded; if it shorts to the engine, the mower won’t start or run. Finally, consider replacing the coil. These are not user-serviceable, but they are affordable and critical to starting and running your mower.

Batteries die for a living

By far the most common element of the ignition system that can prevent a riding mower’s starting is the battery. Almost 20% — 11.8 million — of Google’s search results for the word battery include the phrase dead battery, because that’s what batteries fundamentally do: expend all their energy and die. And lawn mower batteries are almost always flooded lead acid batteries, which die more easily and more thoroughly than any other sort.

A lot of the work of fixing a battery problem is the same as properly maintaining the battery to begin with. That is, it’s stuff you should do regularly anyway. So, clean the battery terminals with a wire brush (clamp-on terminals might require a special type of brush, often cone-shaped). Use battery terminal cleaner if it’s necessary, though it rarely is. Make sure all electrical connections are clean and tight. Batteries that haven’t been maintained with a trickle or Smart charger while in storage, such as over the winter, will probably need to be charged and will sometimes even need to be replaced. If your battery is in good condition, check out your alternator and starter. Testing an alternator is simple on equipment with working headlights, as many riding mowers have. Just observe the lights. If they don’t dim when you turn off your engine, you probably have an alternator problem.

After verifying that you have a fully charged battery and a working alternator, check all the wires connected to the alternator and starter for damage. (You can test them with a multimeter if you’re suspicious of their condition.) If everything else checks out, test your solenoid and starter switch using the procedures outlined in this Briggs Stratton guide.

Fuel troubles

Every now and then you’ll see news about a possible perpetual motion machine devised in a scientist’s lab (or mind), but until you can pick one up at Home Depot, you’re going to be dealing with fuel for your lawn mower. This usually means gasoline, and there are a few common points of failure small engines can experience when trying to get fuel from the tank to where it’s needed for internal combustion.

First, make sure you have gas in the tank to begin with. This gets overlooked more often than you might guess, especially when you’re already half-expecting other mower problems and your brain primes the pump by framing everything in that context. Next, examine the age of the gas in use. Did you buy the mower used? Has it been in storage for more than a couple of months? Has the gas itself been sitting in the gas can for a while? Gas can go south in as little as a month, so if someone’s telling you it can sit for two years (a common number in mower lore) without chemical assistance or consequence, you should take your maintenance advice from someone else.

Mowers should be stored without gas or with an added fuel stabilizer (the aforementioned chemical assistance), to prevent such issues. Old gas clogs and damages fuel lines and carburetors, and won’t start an engine very well even if it makes it to the right place. If you already have old gas in your mower, you might need to remove and clean the fuel system components, as described here by Simple Green.

Fuel troubles: the fuel system

Replace your fuel filter regularly, especially if you’ve had old gas in your engine. If your engine has a fuel pump — and it probably does — it will reside between your fuel tank and the carburetor. When you’re out of options, check that it’s actually pumping by using a guide, like this one from Hello Practical.

There’s also the possibility that you aren’t availing yourself of some aids many lawn mowers have built into them to ensure the proper fuel/air mixture makes it to the engine. First, there’s the priming bulb: usually a clear, rubbery protrusion near the carburetor you can press. It will fill itself with fuel, injecting the fuel system with additional fuel as needed for starting.

You should also learn to use your engine’s manual choke feature properly, if it has one. Many newer engines have an automatic choke, and mowers generally have either a choke or a priming bulb, as they both perform the work of enriching the fuel/air mixture for starting your engine. Start your engine with the choke on, then move it to the opposite position once the mower is running properly. Leaving the choke on will stall or potentially damage the engine. Also, check to see if the tiny hole in your gas cap is clogged. That hole creates a vent to allow fuel to move down the fuel lines, and if it’s clogged, your engine will be starved of fuel.

Air filters

Of course, when it’s time for things to blow up inside your engine’s cylinders, gas is only half of the story. Your choke (if you have one) tells the other half: You also need air to mix with the gas, and some mechanisms to help with the mixing. The choke makes the fuel/air mixture richer by restricting (temporarily) the flow of air through the carburetor. Once the engine is running, you should return the choke (and, thereby, the airflow) to normal. But there are a few possible reasons you might continue to have airflow problems.

The first is a dirty air filter. Like most parts of a lawn mower, the air filter is prone to becoming filthier than seems possible. This means it’s doing its job, and it also means the filter requires cleaning or replacing from time to time. A dirty air filter will cause an engine to misbehave in all manner of ways, including not starting easily or at all. Your mower has one or two filters, any of which may be either foam or paper. It’s usually better to replace a paper filter if possible, but otherwise tap it against a hard surface and blow it out gently from the inside with an air compressor.

Foam filters are a bit more involved. Start by tapping and blowing it out like a paper filter, then spray it thoroughly with a filter degreaser and allow to soak for 15 minutes. Rinse under clean running water and allow it to dry, and then apply a filter oil spray. To the extent it’s possible without damaging the filter, squeeze the filter to work the oil throughout. After a few minutes, reinstall the filter and wipe away any excess oil.

air: carburetor

Sometimes your fuel/air mix is off because the carburetor isn’t doing its job properly. In extreme cases, this could prevent the engine from starting. At that point, you must choose between cleaning and rebuilding the carburetor. Fortunately, these processes are mostly very simple. The standard process for cleaning a carb is to remove and clean (or replace) the air filter, then inspect the carburetor inside and out for stray debris. Finally, spray carburetor cleaner into the carburetor while the engine is running, per directions on the spray can.

If this doesn’t work — perhaps because the gum and gunk inside the carburetor is extreme as a result of age or being run with old gasoline — removing and rebuilding the carb isn’t as scary as it sounds. It’s basically a process of taking the carb off and then cleaning everything off of it that you can. It’s also a good idea to take some photos along the way, so you can be sure of how everything goes back together. Finally, just reassemble. Briggs Stratton has a good online overview of this process.

If this makes you too nervous, try adding a cleaning mixture of 4 ounces Sea Foam Motor Treatment and 8 ounces gasoline to the tank. Remove the spark plug(s) and then prime and crank or rope-pull the engine to draw the mixture into the carb. Allow it to sit 24 to 72 hours, then run the engine per Sea Foam’s instructions.

Odds, ends, and tips

There are a few other fairly common situations that can interfere with starting a mower. It’s never a bad idea to change your oil, but be sure to do it properly. Old oil, insufficient oil, overfilling with oil, or using oil that’s the wrong weight (viscosity) for the temperature outside can all contribute to difficult starting.

Keep your mower deck clean; an overabundance of grime and debris can slow blade rotation and hinder starting. Similarly, if you’ve run into something recently with your mower, inspect the mower deck to make sure the blades can rotate freely. A blade striking the deck can prevent the mower from starting altogether.

Finally, there’s the unpleasant business of the starter rope — that thing you yank on a mower with a recoil starter. There are two types of mower owners: those who have cursed the fortunes and questioned the character of mower manufacturers for inventing the recoil starter, and those who haven’t used a recoil starter at all. Common causes of starter rope problems include overfilling with oil and debris interfering with rotation in the mower deck, as mentioned above. Similar problems include bent mower blades and damaged mower deck shrouds. The cord may also be difficult to pull because the flywheel brake (controlled by a bar you must hold while using the mower) is stuck. Try loosening or tightening the cable, then repeatedly open and close the bar that engages the flywheel brake. If this doesn’t work, you might need professional assistance. If you feel up to it, Briggs Stratton has flywheel brake replacement instructions. Similarly, a hydrolocked engine (one that has seized after getting water in the engine) will normally require professional help, unless you’re up for these steps from Garden Guides.

Problems that aren’t (exactly) problems

Sometimes you’ll hear that the cause of some problem is a feature and not a bug, but the distinction isn’t helpful if you can’t start your lawn mower. The best example of this is a mechanism called a safety interlock (or often safety switch), by which your mower won’t run because some other thing isn’t quite right. For example, riding mowers that won’t start unless you’re sitting in the seat. Some cars have interlocks that prevent you from operating them if you’ve had a few beers, but fortunately mowers don’t have this feature yet, as it would prevent about 90% of Saturday afternoon lawn mowing from happening at all.

The safety switches on most riding lawn mowers include a seat switch that will not allow the engine to run unless the seat is occupied; a PTO safety switch that might prevent the blades from turning in certain situations and prevent the mower from starting when (for example) the blades are engaged; a brake switch to keep the mower from starting unless the brake is applied; and a reverse switch, that prevents mowing. Obviously several of these can prevent an engine from starting if they malfunction.

It might be tempting to disable some or all of these safety switches. Don’t — they’re there for good reasons. Unless you’re handy with a multimeter and circuits, dealing with faulty safety switches might be another job for a professional.

Troubleshooting guide

So, how do you know which of these problems is preventing your mower from starting? Let’s look at a few questions that will help you narrow down the most common problems and their solutions. If your mower is full of fuel but only runs for a few seconds, check the pinhole vent in your gas cap for obstructions. This could also be a sign of old gasoline. If the engine hasn’t been run in more than a month, treat the gas as suspect. You might also clean the carburetor and clean or replace the spark plug(s).

If your engine sounds like it’s cranking, but won’t fully turn over, you might have an electrical problem — possibly the starter. If you hear a clicking sound but nothing else, that similarly suggests starter, battery, or related problems. If you don’t hear anything at all when you turn the key, check the starter solenoid and its connections. This also might indicate issues with the battery, coil(s), ignition switch, or safety interlocks. Hearing nothing at all could also indicate that your mower is refusing to start because it is low on oil.

If the engine is cranking slowly, you probably have a failing battery. Check the battery and alternator. If your pull cord is difficult to pull, check that the flywheel brake is disengaged. Be sure you don’t have too much oil in the engine, and that it’s the correct weight for the season. Another sign the engine might be overfilled with oil is the presence of blue or white smoke when it does run. Black smoke, on the other hand, indicates the fuel mixture is too rich. Replace the air filter and check the choke mechanism.

How to Fix CRAFTSMAN Riding Lawn Mower Problems

CRAFTSMAN-riding gasoline-powered lawnmowers are fantastic for cutting larger expanses of grass, such as those found in golf courses or parks. Being able to drive the mower is much more fun and requires far less physical exertion than pushing a mower up and down in the blazing sun.

CRAFTSMAN Riding Lawn Mowers offer many advantages but do occasionally develop problems:

Engine won’t start

Blades won’t engage

Runs for a bit, then dies

Won’t cut lawn evenly

Won’t drive forward

Doesn’t steer correctly

Exhaust billows smoke

And more …

Engine Won’t Start

We all know the disappointment when you’re all “dressed up” and ready to tackle the first lawn-cutting exercise of the season, only to find that your trusty CRAFTSMAN riding mower won’t start.

The CRAFTSMAN riding mower is, of course, fitted with a gas engine which means several problems could be causing the engine not to start. The below covers the common reasons why the engine doesn’t start.

Solution 1: Drain and Replace Old Gas

Check that the gas tank contains fuel, especially if the mower has been standing for an extended period. Gasoline degrades over time and evaporates.

Old gas should be drained from the system and replaced with new to eliminate this problem.

Solution 2: Replace the Fuel Filter

Following the gas line from the gas fuel tank to the carburetor will lead you to the fuel filter. The filter may be dirty, restricting or preventing fuel from reaching the carburetor so the mower won’t start.

If the fuel filter is visibly dirty inside, replace the fuel filter to ensure the gasoline can pass through the filter.

Solution 3: Ensure All Safety Cutoff Switches Are Engaged

CRAFTSMAN riding mowers have two safety switches that ensure the mover won’t start accidentally. One switch is under the driver’s seat, and the foot brake controls the other.

Their design is such that the driver must be seated on the seat, and the brake must be depressed to disengage the safety switches for the mower to start. Standing next to the mower while trying to start the engine will not work.

Solution 4:Charge the Battery

All CRAFTSMAN riding mowers have a battery located under the driver’s seat to turn and start the engine. When turning the ignition key and the engine turns very slowly but won’t start, the battery is most likely discharged.

Turning on the ignition and hearing a clicking sound without the engine turning is a sure sign that the battery is drained and needs to be charged.

In both scenarios, the battery requires charging, or if the problem persists, the battery may need replacement.

Solution 5: Clean or Replace the Solenoid

The carburetor fuel solenoid is attached to the base of the carburetor. The carburetor controls the fuel and air mixture required for the engine to run. The solenoid is an electrically operated fuel supply and shut-off valve. When the valve doesn’t work, it prevents fuel from entering the carburetor.

Diagnosing if the solenoid is faulty is quickly done by getting an ear down close to the solenoid. A click sound will be heard when the key is turned on and off as the solenoid retracts and releases. If no sound is heard, the solenoid is likely faulty and requires replacement, or the mower won’t work.

The solenoid will need to be removed by unscrewing it with a spanner of the right size and cleaned or replaced if the cleaning doesn’t work.

Solution 6: Replace the Filter

The air filter is next to the carburetor and filters the air fed into the carb. When the air filter is filthy, it may get clogged up by dust particles. The clogged-up filter will prevent air from reaching the carburetor and the engine from starting.

The solution is to replace the filter with a new one.

Solution 7: Replace the Spark Plug

The spark plug performs the critical task of igniting the fuel in the cylinder head while the engine is running. The spark plug is constantly exposed to burning gas and oil residue; therefore, the spark plug can quickly become dirty.

Removing the spark plug is a simple exercise using a spark plug spanner. A dirty spark plug can be cleaned using a wire brush but will eventually need to be replaced. Instead, replace the spark plug to be sure it’s working well.

Blades Won’t Engage

Your CRAFTSMAN riding mower is running, you’ve reached the area that needs mowing, but now the blades won’t engage. What could be wrong?

We’ve found five possible causes for the blades not engaging with CRAFTSMAN riding mowers. These problems may differ depending on if your mower has a manual lever clutch or an electronic PTO clutch.

Solution 1: Replace the Electric PTO Clutch

Faulty PTO clutch. When power is supplied to the clutch, the clutch engages and turns the mower’s blades via the drive belt. When the PTO clutch doesn’t engage, the internal mechanism has failed.

The PTO clutch is not a repairable part as it’s a sealed unit, so it needs to be replaced.

Solution 2: Remove and Test Take-off Switch

The second reason the blades won’t engage on the electrically operated unit is a faulty power take-off switch. This switch is located on the dashboard of the mower and is usually yellow. Pulling the switch engages the blades, while pressing the switch disengages the blades.

Removing the switch and testing it for continuity using a multi-meter is the best to determine if the switch won’t work. If faulty, the switch would need to be replaced as you can’t repair it.

Solution 3: Replace Drive Belt

Before we deal with the manual clutch mowers, one common item between the electric clutch and manual version mowers is the drive belt.

The drive belt is located underneath the mower and connects the crankshaft to the mower blades via the clutch assembly.

The drive belt is a high-quality V belt, similar to those used in model car engines. When this belt becomes excessively worn or is damaged or cut, it can no longer drive the mower’s blades, which won’t work.

The drive belt must be replaced when damaged or worn out.

Solution 4: Replace Lever Mechanism Unit

CRAFTSMAN riding mowers fitted with a manual clutch can suffer the following failures over time that prevent the mower’s blades from engaging.

The clutch engages and disengages the blades on the manually operated version. The clutch is operated by pulling down a lever on the right of the dashboard. A cable connects the lever mechanism to the clutch located under the mower.

The lever mechanism in the dashboard can fail over time, making it impossible to retract the cable connected to the clutch.

A failed lever mechanism will require the replacement of the unit.

Solution 5: Replace Broken Clutch Cable

Broken manual clutch cable or spring: The cable, as mentioned earlier, connects the lever mechanism, and the clutch, along with its tensioner spring, is wearing parts, so it can fail with excessive use and eventually won’t work.

A broken or severely worn clutch cable and its accompanying tensioner spring must be replaced should they fail.

Runs for a Bit, Then Dies, Won’t Work

The CRAFTSMAN riding mower is reliable and generally doesn’t cause problems. Occasionally, you may find that your mower starts up and then dies. When you crank it, it starts, only to turn off again.

Solution

Briggs and Stratton’s engines used in CRAFTSMAN mowers are four-stroke engines, so they use unmixed fuel (no two-stroke oil required). They generally run very clean and shouldn’t develop any carburetor blockages.

Fuel starvation is the most likely cause of the engine starting and then stopping shortly after.

Assuming the fuel tank is sufficiently filled and contains fresh fuel. The motor dies because the fuel entering the carburetor flows in slower than the outflow of fuel into the engine; effectively, the carburetor runs dry, which causes the problem.

The cause is a blocked fuel line or clogged fuel filter. 10% Ethanol fuel is tough on rubber fuel hose and causes the fuel line to degrade internally. This degradation blocks or severely reduces fuel flow from the tank to the engine.

Replacing the fuel line and filter will restore the fuel flow to the motor and prevent the engine from turning off when you least need the problem.

Won’t Cut Lawn Evenly

Cutting a large section of lawn only to realize that you’ve cut a series of steps into the lawn’s surface can be disappointing. How does this happen?

Solution

An uneven cut results from the mower deck (cutting blades) not being set to the correct height, or your mower may have a deflated tire causing the problem.

A mower-cutting deck rides on a series of linkages. They allow the deck to be adjusted up and down to adjust the cutting depth.

An underinflated or flat tire can play havoc with the angle of the cutting blades. If the blades are not level with the ground and cut deeper on one side of the mower, it will result in an uneven cut. So make sure all the tires are inflated to the correct pressure.

Cutting deck adjustment is made through two adjustment bolts. One adjusts the height seen from the left and right of the deck, and the other changes the front and rear deck height. It’s quick and easy! We’ve attached the below YouTube video, which details how the adjustments are performed.

Won’t Drive Forward

Like so many other mechanical devices, excessive use of a CRAFTSMAN riding mower will eventually take its toll. Occasionally something may go wrong, preventing it from driving. The gear lever is one of the items on a mower that sees a lot of use as it’s constantly shifted between drive, neutral, and reverse.

Solution

The linkage joining the gear selection lever and the actual gearbox may go out of alignment or get clogged up with dirt, preventing the gear levers from traveling the entire distance to engage or disengage a gear. Of course, the gearbox could be faulty, but this is unlikely as they’re robustly built.

Following the gear level selector down below the right fender of the mower will reveal the linkages that would need adjustment when gear selection becomes difficult.

Given that the linkages vary from model to model, it may be necessary to enlist a professional. Alternatively, some trial-and-error adjustments may do the trick.

A build-up of dirt inside the linkages is a real problem. The underside of the mower is exposed to a lot of dust generated by the spinning blades.

Carefully removing the various parts of the gear selection linkage will reveal dirt that prevents the levers from shifting their entire length of travel, preventing the shifter from working. Removing the dirt will enable the gears to be selected and allow the mover to drive.

Doesn’t Steer Correctly

The CRAFTSMAN riding mower follows a traditional tractor design, having two driving wheels at the rear and two front wheels that provide steering by turning left and right. The driver operates a steering wheel precisely like you would when steering a vehicle.

Over time the steering mechanism of the CRAFTSMAN riding mower is prone to developing a problem with turning to the left but normally turns to the right. Fortunately, this is a pretty simple fix.

Solution

The CRAFTSMAN steering mechanism is pretty basic, consisting of a steering column housing a gear that connects to a gear plate. The gear plate connects the left and right front wheels via a metal rod or linkage. The gear plate rotates as you turn the steering, changing the wheels’ direction.

The steering column’s base gear plate is slotted to limit the wheel’s rotation to either side. Over time the slot located in the gear plate becomes clogged with dirt which is compressed into a solid mass inside the slot or cut out, causing left turns not to work.

The dirt build-up inside the slot limits the gear plate’s movement, limiting the wheels’ ability to turn. The plate design seems to create the problem when turning left only.

The gear plate needs to be removed to get the wheel turning again, which is more straightforward than it may sound. The dirt and grime build-up must be removed from the slot in the gear plate, and the area housing the plate must be cleaned. Once the dirt is removed, the steering mechanism will function.

Exhaust Billows Smoke

Even a great engine such as the ones used in the CRAFTSMAN riding mowers can develop a problem where white smoke starts billowing from the mower’s exhaust. The problem can become so bad that the engine won’t work.

Solution

Worn piston rings can cause the mower’s engine to billow smoke, but this tends to happen slowly over time. If a perfectly good running engine suddenly starts billowing smoke, the cause is likely a blown head gasket.

The head gasket seals the space between the cylinder head, which houses the valves, and the part of the engine housing the piston. When smoke starts billowing from the exhaust, it’s a sign that oil and even water are entering the combustion chamber, where the oil ignites and starts smoking.

Replacing the cylinder head is a task best left to a mechanic as additional damage, such as a cracked head, may have developed and would require identification and repair.

Vibrates a Lot When Mowing

Vibrations are common amongst riding mowers as they bump and grind their way. Excessive or new vibration is not good, meaning something has a problem.

Numerous problems can cause vibrations, but the most common is a blade or blades that have become unbalanced or, in older machines, a mandrel that’s gone faulty. The mandrel contains a shaft supported by bearings. The mandrel houses the blade on one end and a pulley around which the drive belt runs.

Numerous problems can cause vibrations, but the most common is a blade or blades that have become unbalanced or, in older machines, a mandrel that’s gone faulty. The mandrel contains a shaft supported by bearings. The mandrel houses the blade on one end and a pulley around which the drive belt runs.

Solution 1: Replace Worn or Damaged Blade

CRAFTSMAN blades are made of high-quality hardened steel, which lasts a long time. Blades take the brunt of the force when cutting grass; although one tries to avoid it, they strike a rock occasionally. The impact can bend or even break a blade piece, which can cause vibration.

The solution is to replace the damaged blade with a new blade. A replacement will stop the blade from vibrating.

Solution 2: Replace Worn or Damaged Mandrel

A worn or damaged mandrel can cause the mower to vibrate. Although mandrels are a sturdy kit, they can eventually wear and fail, causing vibrations.

The mandrel needs to be replaced to fix this vibration, per the YouTube video below.

Lawn mower won’t start troubleshooting video: fuel, ignition and compression problems video

A clogged air filter, bad spark plug or contaminated gas can prevent your walk-behind lawn mower from starting. Troubleshoot the problem with this Sears PartsDirect video, which shows how to check engine compression, clean the fuel line and look at the choke linkage, return spring and carburetor.

Check out our DIY Walk Behind Mower Repair page for more troubleshooting videos, repair guides and answers to commonly asked questions.

Today we’re talking about some troubleshooting steps to figure out why your lawn mower won’t start. Although your mower might look different from this Craftsman 21-inch mower, they all work pretty much the same.

These are the tools and supplies you might need, depending on the problem.

Tools and equipment needed

• Starting fluid
• Fresh gasoline
• Ratchet and deep socket
• Spark plug tester
• Compression gauge
• Shop rag
• Fuel-safe container
• Pipe cleaner
• Carburetor or carburetor rebuild kit

Fuel, spark and compression

Since we’ll be working around gasoline, choose a well-ventilated area free of open flame or sparks.

For an engine to start and run when you pull the recoil starter rope, it needs 3 things. The first is fuel, which is a combination of gasoline and air that mixes in the carburetor. Then it needs a spark from the spark plug to ignite that fuel in the cylinder. Finally, it needs the right amount of compression in the cylinder to drive the piston. To fix your problem, we’ll have to figure out which of these three is missing.

We’re going to start by checking a few easy things.

Check the air filter

A clogged air filter can keep air from getting to the carburetor and mixing with the gas.

Remove the air filter cover and pull out the air filter. This mower has a pleated paper filter, but yours might be a different type of paper filter, or it might be foam. If you have a paper filter that’s just a little dirty, you can tap the filter on a hard surface to clean it. If it’s completely clogged, then you need to replace it. If your mower has a foam air filter, you can find cleaning instructions in your owner’s manual.

Check for a fuel problem

While the air filter is removed, let’s do a quick test to see if the engine has a fuel problem. Spray starting fluid through the air filter opening to the carburetor and then try to start the engine.

If it doesn’t start, that eliminates a fuel problem, leaving spark and compression on our list of suspects. If the engine starts and runs briefly, click here to skip to the section about diagnosing fuel problems.

Spark plug and compression

Check the spark plug first. Pull off the spark plug wire and remove the spark plug, using a ratchet fitted with a deep socket. Look for carbon or oil buildup on the spark plug electrode that could prevent sparking. Also, look for a crack in the ceramic insulator. If you see excessive buildup or a crack, replace the spark plug.

If the spark plug looks good, reinstall it and then connect a spark plug tester to check the ignition system. Release the rope from the mower handle so it’s in reach when testing the spark plug. Connect the tester boot to the spark plug and connect the spark plug wire to the other end of the tester. Clamp the bail control bar down to release the blade brake. Pull the starter rope and see if the tester sparks. If the tester shows that there’s no spark, follow the steps in our video about troubleshooting the ignition system.

If the spark plug is good and the ignition system works, check the cylinder compression. You need a compression gauge for this test.

First, remove the spark plug from the cylinder and pull the starter rope several times to purge fuel or oil from the cylinder. Insert a compression gauge in the spark plug hole and push the button to zero-out the gauge. Pull the starter rope repeatedly, until the needle on the gauge stops rising. The gauge should measure between 40 and 60 psi of compression. If it’s lower than 40 psi, have a service technician examine the engine and fix the compression problem. The technician has the right tools and the expertise to diagnose low compression.

Testing the gas, tank

Now, if the engine started and ran briefly when you did the starting fluid test, you know the spark and compression are okay and the problem is in the fuel system. For these tests, be sure you’re in a well-ventilated area where gas fumes can’t build up.

First, let’s look at the condition of the gas. Old gas that has absorbed water or gas that has dirt in it can keep a mower from starting. If your gas has been sitting around a while—either in the tank or in the can—drain the tank and fill it with fresh, clean gas from a clean gas can.

In the future, if you’re going to leave gas in the tank for a while, add fuel stabilizer.

To drain the tank, lay a shop rag on the mower deck below the tank to catch spills. Place a clean, durable container under the fuel line connection on the bottom of the tank. Release the fuel line clamp and pull the fuel line off to drain the gas into the container. For information on disposing the gas safely and legally, check with your local fire department or hazardous waste recycling center.

If you find debris in the drained gas, check for a contaminated fuel tank. Use a flashlight to look inside the tank for grass or debris. If you see debris, release the rope from the mower handle and then remove the three screws from the lower housing. Remove the blower housing and pull the tank off the engine. Rinse out the tank with water and let the tank dry completely before reassembling the mower. Don’t pour that water down a drain. Dispose of it correctly along with the old gas.

Checking the filter screen, fuel Line

After rinsing out the fuel tank, check the filter screen at the bottom of the gas tank for damage. On this style of engine, the screen isn’t available as a separate part, so if the screen is damaged, you have to replace the tank. Some tanks have a removable fuel filter that you can clean or replace. Check your owner’s manual for more information.

You should also check the fuel line for a crack or clog. Disconnect the other end of the fuel line from the carburetor. Examine it for cracks or cuts and replace it if it’s damaged. If you don’t see any damage, look through the fuel line and clear any clogs with a pipe cleaner.

Determining carburetor issues

If you’ve ruled out the quality of the gas and the fuel line, it’s time to turn to the carburetor, which mixes gas and air that is drawn into the cylinder.

Let’s start with the carburetor choke plate. The choke plate controls the ratio of gas and air sent to the carburetor depending on engine temperature. The engine on a lawn mower that’s been idle for more than an hour is cold and needs less air to start. In this case, the choke plate should close to temporarily restrict airflow through the carburetor so more fuel can enter the cylinder.

A choke plate that’s stuck open could prevent the cold engine from starting. Check the choke plate by looking through the carburetor air inlet on the air filter base. The choke plate should be fully closed. If the choke plate is open, check the choke thermostat and linkage. First, remove the air filter base to access the choke linkage and choke thermostat. Remove the blower housing if you didn’t already remove it to rinse out the fuel tank.

Examine the choke linkage and return spring to see if they’re connected properly and moving freely. Reconnect the choke linkage and return spring and replace any broken parts. If the choke linkage and return spring looked good, then your choke thermostat is likely stuck. Replace the choke thermostat if it’s stuck in the open position.

Instead of a choke plate, some engines have a primer bulb that you press to force more fuel into the cylinder when starting a cold engine. Replace the primer bulb if it’s damaged.

Replace or rebuild carburetor

If the choke plate or primer bulb work, it’s likely you need to replace or rebuild the carburetor. Here’s a video that shows you how to replace the carburetor.

Or, you could rebuild the carburetor, which takes more effort but costs less. Order the carburetor rebuild kit and then clean and rebuild the carburetor if you want to save money on parts. Here’s a video that shows how to rebuild the carburetor.

Once you restore the fuel flow to the engine cylinder by replacing or rebuilding the carburetor, the engine should start.

I hope that this video helps you out today. Be sure to check out our other videos, here on the Sears PartsDirect YouTube Channel, and subscribe if you like them.

So you are trying to get the lawn mowed, and your trusty mower won’t start?

How frustrating!

The lawn needs to be mowed, but the tool you need the most is not up to the task.

Good News! Most of the time a mower will start after some basic troubleshooting.

So what should you do next?

Here are a tips on some quick troubleshooting.

If you have a push mower this can be pretty simple.

Let’s take a look at the 5 steps you can take to get your mower up and running.

Start with the basics…. does it have gas in it?

Silly question, I know, but double check.

Time to check the air filter-

Take the air filter cover off, and remove the filter.

The air filter cover will be a plastic rectangle usually on the left or right side of the motor. Though, sometimes they are on the front. You may need a screwdriver to get the cover off, but most of the time they pop off easily, or have a fastener that can been removed by hand.

Now remove the filter, it could be stopped up with debris and this could be the problem, lightly tap the filter against a concrete surface to remove the debris, then use a vacuum cleaner to clean the rest of the debris.

While the filter is off try to start the mower quickly. Sometimes the filter gets covered in fuel, or is just too dirty for it to start.

Not recommending this, but in my experience have run a push mower for over a year with no air filter. I had to remove it to start the mower. Here’s the thing, the mower deck fell apart before the engine ever did.

IF the filter is torn, or your mower only starts when it is off you will need to replace. The Home Depot, Lowes, your local hardware or auto store should stock them. If you have time to wait, do a search online, enter the mower make and model into Google and you should be able to find it.

If you are having difficulty with the filter check out this lawn mower air filter guide.

Still nothing? Try Starter fluid.

Bad gas, clogged lines, and flooded motors are common issues for a mower not starting.

Now that you have cleaned the air filter, try spraying some starter fluid into the engine.

Behind the air filter there is a hole. Spray the starter fluid for 2-3 seconds into the hole behind where the filter sits. Then quickly try to start the mower.

It would be best if someone helped you pull on the starter cord repeatedly while you spray the fluid into the engine.

Most of the time this will get it started. Once you get it running, spray some of the carb cleaner into the carburetor while it’s running, this will clean the carb and prevent issues down the road.

Careful while you do this the blade is spinning!

Nothing again? Clean the carburetor and gas lines.

Water in the gas line, or just plain bad gas will prevent the mower from starting.

In most cases you can remove lower part of the carb by removing one bolt, which is located at the lowest part of the carb, see the photo below.

But first! You will need to drain the gas tank, assuming you have bad gas or water in the tank, you need to empty the entire tank.

Now that the gas has been removed, its time remove that bolt at the end of the gas line below the air filter. You can undo the bolt (see photo below) while the carb is still mounted on the mower. Keep in mind gas will come out. Once the bolt and reservoir are removed, flush the lines with good gas (safely and legally). Also clean the gas bowl with good gas.

Put it all back together, and fill it with good gas. Will it start now?If not, cleaning the entire carb takes longer, but may be necessary. Use this guide to do a complete carb cleaning.

By now I assume most of you are cutting your gas, but if none of that works….

It’s time to check the spark plug,

The spark plug will be on the front face of the engine and will have a rubber boot with a wire coming out of it that is connected to the tip of the spark plug. Make sure that rubber boot is connected properly.

Try starting again, if you still have no luck.

Most people don’t know this, but it’s time to remove the spark plug and replace it. You will need a spark plug wrench. If you don’t have one they can be purchased in the lawn and garden section of any major store, or at any auto parts store.

Remove the plug and take it to an auto parts store, and they will be able to match it up with the correct plug. Reinstall the new plug and try to fire it up again.

Sadly, if you are still here, then you could have more serious issue such as an internal motor problem or a bad carburetor.

Then it’s time to take it to a professional.

What’s the point?

If you have used these 5 Steps,

• Check for gas
• Check the air filter
• Try starter fluid
• Clean the carburetor
• Change the spark plug

And it still won’t start you may need a new mower.

Here’s why, in most cases when it comes to a push mower it is not worth spending the money to have a professional repair it. A decent push mower can be bought for 200-500.

IF you drop it off at the lawn mower shop it’s going to be a minimum of 50 to look at it ,and before you know it you could possibly have a 200 repair bill in a mower that is not worth that.

I hope these tips helped out, and get you back running again.

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