Lawn mower starter relay. How To Tell If Your Lawn Mower Starter Solenoid Is Bad

How To Tell If Your Lawn Mower Starter Solenoid Is Bad?

A Lawnmower starter solenoid is an on/off electromagnet switch installed near the mower battery. It gets a signal from the battery as you turn on the ignition key and delivers a large wave of energy to the starter motor, allowing it to start. But how to tell if lawn mower starter solenoid is bad?

Mower engine starting failure, strange clicking noises, black smoke emission, a dead battery, or incorrect battery/electrical connections are all signs of a bad starter solenoid.

Continue reading this article to learn how to detect a bad starter solenoid and exactly how to replace it.

How To Tell If Lawn Mower Starter Solenoid Is Bad?

If you notice difficulty/complete starting failure as you try to start your mower or a weird clicking sound coming from your lawn mower, it is a clear sign that the starter solenoid on your lawn mower gradually deteriorates or has any issues.

Besides that, you can also notice one or multiple following early signs if your starter solenoid has turned bad so pay attention to ensure whether the starter solenoid is good or bad.

Causes Why A Lawn Starter Solenoid Can Turn Bad

The most common reasons behind your lawn mower starter solenoid turning faulty or bad are:

  • Built-up Moisture near the engine bay of your mower
  • Corroded/Broken wiring or poor (old or loose) connection
  • Mower engine overheating due to warmer weather
  • Excess electricity flowing inside the mower starter solenoid for an extended period
  • Old or deteriorated starter solenoid

How To Test Your Lawn Mower Starter Solenoid? (6 Easy Steps)

As soon as you notice any of the earlier signs, you should first confirm that the problem is only arising due to the bad starter solenoid and that no other faulty elements are causing this error.

To confirm that you test the solenoid by following these steps.

Check the Battery

Inspect your mower battery to confirm whether it has 12 Volt or not to make sure it is fully charged.

Remember if you notice that your lawn mower battery keeps draining faster than usual, a bad solenoid is not the only driving force, and it can also happen due to other defective parts.

So, you need to test the battery to confirm it.

Take a digital multimeter to test the battery and if the battery is dead or the volt is continuously dropping, remove and replace the battery before moving forward.

Make sure the brake is locked, the blades are turned off transaxle is neutral.

Check if the brake is pressed down and it’s in the locked position.

If not, position the brake accordingly and confirm that the mower blades are turned off.

Also, make sure the transaxle is in the neutral position.

Locate the Starter Solenoid on your Lawn Mower

In some lawn mower models, the solenoids are mounted under a panel behind the steering column underneath the gas tank.

But in some other models, you can locate the solenoid under a panel between your legs if you are sitting on the mower, and on other lawn mower models, you will locate the solenoid under the panel below the mower back seat.

The actual solenoid location will depend on which model lawn mower you own, and you can confirm it with the help of your mower’s user manual.

Determine Whether it’s a Three or Four Pole Solenoid

Once you have located the starter solenoid on your mower, you need to determine whether you have a three-pole solenoid or a four-pole.

Now how to identify whether you have a three or four-pole solenoid?

Look at the starter solenoid closely and if you find three places on your solenoid to attach the wires, it is a three-pole solenoid.

But if you can see four spots to connect the wires it means you have a four-pole solenoid.

Disconnect the Bottom Wire(s) and Connect the Multimeter

Now disconnect the little wire, and if it is a three-pole, it’s going to be the only wire on the bottom.

But if it is a four-pole, it will be on the bottom left-hand side.

Now set your multimeter to DC volt 20 or anything above 14 volts.

Then take the positive side of the multimeter and attach it with that disconnected little wire.

Take the negative side to connect to the ground (whether it’s a bolt or engine frame, either one will be enough).

Test the Starter Solenoid to Confirm its Condition

Turn the ignition key to the start position. Check whether the meter reading shows at least 12 volts or something below that.

If it shows something below 12 volts, it means one of the safety switches or grounds has gone bad, and you have to investigate further to confirm that.

But if you see 12 volts, connect the little wire back to the solenoid and take the positive lead to connect to the top right-hand side cable.

Once again, turn the ignition key on and if you cannot see 12 volts, it means either you have a bad starter solenoid ground or a bad solenoid.

How To Replace a Starter Solenoid on A Lawn Mower?

The only solution to get rid of a bad lawn mower starter solenoid is to replace it with a new one _

Required Tools:

Step 1: Turn the ignition switch off to remove the key and lift the seat to remove the bolt connecting to the battery negative cable.

Step 2: Lift the insulating cover to remove the bolt connecting to the battery-positive cable. Then, lift the battery out of the battery box and release the seat switch wire harness clip from the seat bracket.

Step 3: Lift the battery box out of the mower body and set the box on the fender. Note the wires connecting locations to the starter solenoid or take a photo so that you can reconnect them accordingly.

Step 4: Remove the mounting nuts from the terminals and pull the wires from the respective posts. Now pull the wires from coil spades and take off the solenoid mounting bolt.

Step 5: Bring the new starter solenoid and connect the mounting clips. Then, position the new starter solenoid on the frame and install the mounting bolt securely. Re-insert and connect everything else accordingly.

Maintaining a beautiful lawn can be a daunting task, especially if you lack the appropriate know-how and tools to handle the challenges that may crop up. Fortunately, LawnAsk is here to offer you an all-encompassing resource that covers everything you need to know about lawn care.

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Lawn Tractor Won’t Start No Click – Fix it now!

Before we assume there’s a problem, let’s take a minute to check that we’re following the correct starting procedure. All mowers will have safety sensors fitted, and if the sensors are open, they won’t start.

So why won’t your lawn tractor start, not even a click? The most common reason for a no start, not even a click sound, is a totally flat battery, but other likely causes include:

A tractor mower won’t start if the blade lever/button is on, manual mowers need to be in Neutral gear, and some mowers won’t allow starting if the oil level is low or the hood is open.

If you are in any doubt about the correct starting procedure for a lawn tractor, check out – “How to Start Husqvarna Ride-on Mower.”

If you do hear a click sound when you turn the key, check out – “Mower Wont Start Just Clicks.”

Check Battery Connections

To test a battery, you need a voltmeter, but if you don’t have one, try this basic check. If your mower has hood lights or dash lights, go ahead and turn them on. If they light up and are bright, your battery is most likely not the problem.

Dash Lights are Dim

Check – Check the battery cables; they should be clean and tight. When connections are loose or corroded, it prevents available power from flowing to the starter.

Charge Battery – If your battery is completely flat, it will take a couple of hours and will require a battery charging hack, or check out this Smart battery charger the NOCO Genius1 on

Jumpstart Mower – This is the fastest solution, but it may not be the long-term fix. (see Jump starting below)

Battery Check Hack

  • Turn on the lights to check for power supply
  • If they work – the battery is likely OK
  • If lights are dim – check battery cables
  • If cables clean and tight – charge battery
  • If you have no lights – check battery with a volt meter

Volt Check – Need a voltmeter for this test. Check b attery voltage – 12.65v is 100%, 12.30v is 70%, and 12.05v is 50% charged. This battery needs a charge.

Very low volts indicate the battery is likely faulty, and it may not recharge. To test a battery, it must be charged, so a battery charger may be required. However, it is possible to jump-start the mower (see below), and given time, the mower’s alternator will charge the battery, assuming it isn’t faulty.

Once the battery is sufficiently charged (about 70%), try the crank test.

Battery Crank Test – Attach the Voltmeter and crank over the engine; if the volts read less than nine, replace the battery. (The battery must be over 70% charged for running this test)

Check out the Amazon link below for quality mower batteries delivered to your door.

Voltmeter – If the lights don’t work at all, you’ll need to use a voltmeter to check the battery’s state of charge. You may have blown a fuse (see below).

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If you have very low volts, the battery is likely faulty. The average life of a battery is four years, more if well cared for.

Jumper Cables

If you don’t have a charger, you can still get it running, but you’ll need a set of jumper wires, and a car or any 12-volt battery will do the job. Follow this link for a more detailed guide to Jump Starting.

Jumpers – Use good quality jumpers.

If you are unfamiliar with jump-starting, you’ll find a complete guide here, “Jump starting riding mower.”

Add the cables in sequence 1, 2, 3, and 4 to start the mower, and while idling, remove jumper cables in reverse order 4, 3, 2, and 1.

Dash Lights Don’t Work

Main Fuse – If the battery is fully charged and still no go – check the main mower fuse. Some mowers will have the blade-type fuse; others will have the old-style bottle type.

When the fuse blows, all power is lost; changing it is simple. It is important to replace the fuse with the correct amp rating. If the fuse keeps blowing, the rating is too low, or there’s a short-to-ground wiring fault.

Fuse Location – Places they like to hide include under-seat, under the hood, behind the fuel tank, and control module incorporated. Modules are usually under the dash panel.

Replacing the fuse is simple, just pull out the old one and push the new one into place. It’s important to replace it with the correct amp rating. Otherwise, you can damage the wiring circuit and components.

Check Safety Sensors

Riding mowers are designed with safety features built in to protect us from operator error or accident. Safety features on mowers are controlled by sensors/switches, and most modern mowers will wire those sensors into a control module.

The sensors are a very simple on/off switch type and rarely give trouble; it’s more common for the striking plate that pushes on the sensor to be misaligned; when this happens, the sensor is open, and the engine won’t start or stops depending on where the sensors fitted.

Over-riding – Sensors can be overridden for test purposes, remove and join the wires, and some sensors are wired in reverse – meaning, just disconnecting them will override the sensor. You can check sensors for continuity using a voltmeter.

Starting Procedure

As you know, there’s a starting procedure that must be followed before your mower will start. You can check out the starting procedure here – “How to Start a Husqvarna Ride-on Mower.”

There are several sensors that must be engaged; the location and number of sensors are dependent on the make of the mower and differs between manual and hydro-static (type of transmission).

The main sensors are the brake pedal; seat; gear lever; blade engage control switch or lever, and some models, such as John Deere, will have one fitted to the hood (Hood open – no start).

Safety – For our safety, sensors are fitted to the seat, blade engages lever or button, transmission selector, brake pedal, and on some models, the hood. Any of these sensors will prevent your mower from starting.

On older manual transmission mowers, the gear selector wears, and although the selector points to the Neutral position, it’s often still in gear – confirm it’s in Neutral by pushing it forward or back; it should be easy to push.

Sensors – This older style Craftsman / Jonsered / Husqvarna blade lever causes lots of no-start problems.

The lever spring gets weak and leaves the sensor in the open position which prevents starting.

Sensors – The quick fix, hold down the lever to start the mower. The complete assembly is available and not too difficult to fit. Check that all sensors are working, and look to see if the striker plates are closing the sensors fully.

Check wiring to sensors for chafing and that the connectors are secure and corrosion-free.

Check Control Module

Most modern mowers will have a Control module; they are a printed circuit with relays and resistors – they do give trouble. Because the specs vary, I can’t be more detailed.

The function of the control module is to receive a start/stop command from the ignition switch and only output a start command to the starter (via the solenoid) if all the correct sensors have been engaged.

Replacement modules can be on the spendy side, so it may be time to access your old mower; if she needs a ton of love in the blades bearing and belts department, it may be time to look at a new set of wheels.

Module – Wires come loose, have a helper attempt to start the engine while you wiggle the wiring connectors.

Check also for damage, water, or scorch marks on the panel itself.

Check Ignition Switch

Ignition switches are an important part of the ignition system; bad connections here can cause lots of problems. Ignition switches – send commands to the control module if fitted.

If your mower doesn’t have a control module, then the safety sensors are wired inline to the ignition switch – meaning any sensor that is in the open position will leave the ignition switch with an open circuit (No start). These systems are basic and tend to be the most reliable.

Common Problems

Issues with ignition switches: loose wiring at the switch; corroded terminals; broken terminals; spinning ignition switches.

Wiring specs for ignition systems vary, so I can’t be more detailed. Check the ignition wiring for damage, corrosion, or loose wires. Have a helper sit on the mower and attempt a start while you wiggle the ignition wires and connectors.

  • Check ignition inputs – ground and 12-volt supply.
  • Check ignition outputs – 12v to the starter solenoid (or to the control module, if fitted) when the ignition is in the start position.

Switch – Spinning ignition switches cause damage to the wiring and pins.

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Corrosion is another common failure. This usually causes unreliable starting and shutdowns.

Wiggle – Try wiggling the wires at the back of the ignition switch while attempting to start the engine; you may need a helper. Often wires simply come loose but do check them for corrosion.

Related Questions

Lawnmower ignition switch problems? Common Ignition switch problems include:

Hey, I’m John, and I’m a Red Seal Qualified Service Technician with over twenty-five years experience.

I’ve worked on all types of mechanical equipment, from cars to grass machinery, and this site is where I share fluff-free hacks, tips, and insider know-how.

And the best part. it’s free!

Riding Mower Won’t Start Just Clicks – Mechanics advice with pics

This is a problem that usually arises in the spring, and for most, the fix is really simple. You’ve come to the right place, and you’ll be cutting grass shortly.

So what’s the problem with a riding mower that won’t start just clicks. The most common reason for a clicking sound on a riding mower when you turn the key is a flat battery. Other possible reasons include:

Yes, it’s a long list, but you won’t have to check all of them; I’ll bet your problem is one of the first three; I have listed the likely causes in order of commonality.

If your mower won’t crank and makes no click sound – Check out “Lawn Tractor Won’t Start.”

Bad Battery Connections

Bad battery connections are very common, and by bad, I mean the power is not passing from the battery to the cables because the battery connections are loose, dirty, or damaged.

Loose Connections

Battery cables become loose because lawn tractors vibrate a lot; this is why it’s a good idea to service your mower at the start of every season, no matter how well she runs.

Dirty Connections

Dirty connections are usually caused by the weeping of battery acid at the battery poles. The acid then crystallizes, causing high resistance; it looks like a white chalky build-up on the connectors.

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Cleaning Connections

To clean the connections, add a couple of spoons of baking soda and a small amount of water, and pour this onto the acid build-up on the connections and battery poles.

The soda neutralizes and removes the acid; you’ll need gloves and protective eyewear. After removing the acid, go ahead and remove the connectors and give them a good cleaning with a wire brush or sandpaper.

If you have some petroleum jelly, a small coat will prevent a future build-up.

Connector – Mower blades and engines cause a lot of vibration; bolts come loose from time to time.

Check that both connections, positive (RED ) and negative (BLACK – ), are clean and tight.

Cables – Check the cables for damage, and corrosion; mice find them irresistible.

Flat / Faulty Battery

A flat battery is a real pain in the ass. I know what it’s like; you just want to cut the grass, right? The fastest way to solve this problem is to jump-start the mower.

Leaking Battery – Check your battery for leaks before attempting to jump-start. If it leaks and it’s a sealed battery, replace it.

However, it’s usually only wet batteries that leak, so best to check your electrolyte level and top up if necessary. As you know, the acid will burn the skin and eyes, so, you know, gloves, etc.

If the acid build-up is excessive, your battery may be on its last legs, so don’t be surprised if it fails or does so soon.

But if the leaking is excessive, don’t jump-start; replace it. Batteries are easy to fit; just be sure the battery is the correct size, and the poles are in the proper places.

Jump Starting

You’ll need jump leads and any 12-volt vehicle. Most cars, trucks, and even Hybrids have a regular 12-volt battery fitted somewhere. Sometimes finding it is the hardest part. If you’re unsure of the voltage, when you find the battery, a sticker on the casing will indicate 12v.

Of course, your battery might be faulty, jump-starting will probably get you rolling, but the problem will still be there. You can test using a voltmeter test tool, which I’ve listed here on the “Small engine repair tools” page.

To jump-start – begin by connecting the positive red of the mower to the red of the car.Now connect the negative black (-) on the car to a ground (GRD) source on the mower. (Any bare metal will work)

Connect – If you are not familiar with jump-starting, you’ll find a complete guide here, “Jump starting riding mower.” Add the cables in sequence 1, 2, 3, and 4, start the mower, and while idling, remove jumper cables in reverse order 4, 3, 2, and 1.

Battery Testing

You can check the battery and alternator using a voltmeter. Batteries don’t like sitting idle; they were designed to be charged and discharged continuously. A battery that gets fully discharged will sometimes not come back to life.

Use a voltmeter to check the battery voltage, and connect red to positive and black to negative. I have listed a voltmeter on the “Small engine repair tools page.”

Test – Check battery voltage using a voltmeter – attach a voltmeter to the battery and set it to 20 volts.

If you have a reading above 12.5 volts – go ahead and attempt to start the mower; watch the voltage; a reading below 8 volts is a bad battery and needs to be replaced.

Buying a Battery

When buying batteries – wet batteries will not ship with acid. The acid must be purchased, and the battery must be filled and charged; it’s a lot of work.

I would buy a gel or maintenance-free sealed battery; these can be shipped, fully charged, and ready to roll. Check out quality common ride-on mower batteries on the Amazon link below.

Battery Charging

You’ll need a battery charger to keep your battery in top condition over winter. I recommend a trickle/Smart charger; they’re simple to use; pop on the color-coded crocodile clips, plug it in, and that’s it. Forget it till next spring, then turn the key and mow.

I’ve listed a good-quality Smart charger on the “Small engine repair tools” page that won’t break the bank.

Batteries work best and last longer when their state of charge is maintained; off-season charging is always advised. Check out “Mower winter storage video.”

Charge – Always disconnect the battery before charging. Simply connect red to red, black to black, and plug in the charger. The length of time on charge will depend on how low the battery is and the amp rating of the charger. Usually, 2-3 hours cooking time.

Faulty Solenoid

The solenoid is a large relay of sorts. When you turn the key to start your mower, a 12-volt supply from the ignition switch to the solenoid activates it. The solenoid’s job is to connect the battery to the starter motor and crank over the engine for as long as you hold the key.

The click sound is the solenoid trying to work by pulling in the armature; they fail regularly, and I replace lots of them.

However, the click sound can also be made for a few other less common reasons, and without fully diagnosing, you may find replacing the solenoid doesn’t solve the problem.

Hey, if you feel lucky and don’t want to do the diagnosing part, I understand. So, if your battery is full and the cables are tight, go ahead and replace the starter solenoid. They’re cheap and easy to fit.

Check out, “Mower solenoid repair tools” it lists useful tools and parts that will help you nail the repair.

Solenoid – Solenoids are a universal fit; they give lots of trouble.

On the upside, they’re easy to fit and cheap to buy.

Where’s the Solenoid?

Often just finding the starter solenoid can be challenging; I sometimes think that they hide them for fun. If you don’t find it under the hood, try under the rear wheel, behind the gas tank, or under the seat.

The easiest way – follow the red battery cable from the battery. On some engines, the starter and solenoid will be one unit (Kawasaki and Honda engines).

Where? – Husqvarna, craftsman-like to, hide theirs under the rear wheel fender or the dash beside the steering column.

However, most solenoids will be easy to locate. Fitting is easy, but do disconnect the mower battery first.

Solenoid Test

Remove – The first step in testing the solenoid – remove the spark plug.

If, when removing the spark plug, gas pours from the spark plug hole – move on and check “Carburetor troubleshooting.”

Test – Turn the key; if the clicking sound persists – Go ahead and replace the solenoid.

If, on the other hand, the engine cranks over, move on and check for excessive valve lash.

Tight – Check the solenoid terminals; all wiring should be secure and free from corrosion.

Binding Starter Motor

The gear head of the starter motor can bind against the flywheel; this locks the engine and starter motor together. So when you hit the key, all you hear is the click sound.


Testing for this condition involves turning the engine by hand anti-clockwise. Some engines will have a cover over the flywheel; if so, try turning the crankshaft with a ratchet and socket from the underside of the engine.

If turning the motor anti-clockwise frees it up – you have found your problem, the starter motor is binding. Usually, a spray of wd40 on the starter gearhead will fix it. If you are lucky, you can get the straw of the WD40 directed at the gearhead without removing any covers.

Starters can bind for other reasons – worn bearings, worn gear head, misaligned or loose starter motor.

Binding – Starters can bind against the flywheel. To fix it – spray the starter gear with wd40 and retest. If it continues to bind, replace the gear head or complete the starter motor.

Turning the engine anti-clockwise by hand will unlock it.

Excessive Valve Lash

Engines have valves that open and close in sequence. The inlet valve allows the fuel/air mixture in. It then closes and seals the combustion chamber. After the power stroke, the exhaust valve opens and allows spent gases out.

What’s Excessive Lash?

The valve lash describes a precise gap between the valve tip and the rocker arm. As the engine wears, this gap gets bigger and must be adjusted. The inlet and exhaust valve lash will usually be different specs.

AMAZING Solenoid Trick! Try This EPIC Trick! Honda, Kohler, Briggs, Kawasaki

Correct Lash

When the valve lash is set correctly – you crank over the engine, the valves open, and release cylinder pressure. This allows the engine to crank over at sufficient speed to create a spark strong enough to start up the engine.

When the valve lash is out of spec, the valve is late opening which means pressure in the cylinder is too great for the starter to overcome; that’s when you hear the click sound.

Incorrect Lash

Check out “Valve lash adjusting” it’s for a walk-behind mower, but the process is identical. Adjusting lash isn’t difficult but will require an inexpensive tool called a feeler gauge. You’ll find a link to a good feeler gauge set on the “Small engine repair tools” page.

Test – If you can, place your hands on the flywheel screen – try turning the engine clockwise.

If you’re unable, you likely have excessive valve lash. Lash should be checked every season.

Lash – Adjusting valve lash requires an inexpensive tool called a feeler gauge.


A carburetor fuel supply usually consists of a fuel bowl, float, and needle. The float is, as its name suggests, a float. Attached to it, is a needle with a rubber tip.

The function of the float is to lift the needle as the fuel level rises in the fuel bowl. When the fuel bowl is full, the needle will be pushed against the fuel feed port, sealing it.

Hydro-locking – Worn carburetor float needle seals have a habit of leaking gas into the cylinder, and when the cylinder is full of gas, the piston can’t move; this is known as hydro-locking. Because the piston can’t move, the engine will often make a clicking sound as you try to start the engine.

Removing the spark plug and turning over the engine will release the gas, but the carburetor float valve and the engine oil will need to be replaced.

Other signs that your carburetor needle seal leaks are: overfull oil level; white smoke from the muffler; oil leaking from the muffler; gas dripping from the carburetor; a strong smell of gas in the garage.

Fuel Valve Solenoid

Newer model carburetors have a fuel solenoid fitted to the bottom of the fuel bowl; its function is to stop the fuel supply when you shut the engine off. So if you have this newer type of carburetor fitted, you will not likely have a hydro-locking condition.

Leaking Carburetor Valve Seal

Failure commonly occurs in the older type carburetor when the rubber needle seal wears. This results in fuel filling the carburetor and eventually entering the cylinder and crankcase.

Gas in the Oil

If you have gas in the oil, don’t run the engine; the diluted oil offers little protection to internal components. First, fix the issue by replacing the carburetor and then changing the oil.

Check out “Carburetor types” page; it lists popular mower carburetors. Check out “Carburetor troubleshooting” also for more details on the issue.

Check Oil – Too much oil is a sign that your carburetor needle seal is leaking unless, of course, you overfilled the oil yourself.

How to Test lawn Mower Solenoids

Needle – The needle wears over time; they turn pink when worn. The fix – replace the seal or the complete carburetor. Using your manual fuel valve will prevent future problems.

Faulty Ignition Switch

A faulty ignition switch can cause all kinds of problems; the click sound can be caused by a bad connection in or at the back of the switch.

Try the Wiggle Test

When turning the key, wiggle the wiring at the back of the ignition switch and see if it makes a difference. It will very often show you where the fault is. Wiring pinouts are specific to each manufacturer.

Wiggle – Try wiggling the wires at the back of the ignition switch while attempting to start the engine; you may need a helper.

Often wires come loose but do check them for corrosion.

Faulty Control Module

Control Modules are not fitted to all mowers. The function of the control module is to receive a start request from the ignition switch and to output a 12-volt supply to the starter solenoid, but only if all safety sensors are in the correct position.

Control Module Test

Control modules do fail and also suffer from loose connectors. Try the wiggle test on the connectors and check for obvious signs of water/corrosion damage. The control module will often live behind the dashboard in a plastic box about the size of a mobile phone.

Wiggle – Like the ignition switch; wires come loose, have a helper attempt to start the engine while you wiggle the wiring connectors.

Check also for damage, water, or scorch marks on the panel itself.

Faulty Starter Motor

A faulty starter can fail electrically, mechanically, or both. Electrically – the copper winding can break; brushes can break or wear out. Mechanically – the top and bottom bearings and the gear head can wear. These issues can cause the starter to bind, so all you hear is the click sound.

Testing the Starter

Checking the starter motor is easy; connect a 12-volt supply direct from the mower battery to the supply wire at the starter. An even easier way is to cross the starter solenoid as per the guide below.

If you find your starter has failed, removing and fitting a new one is simple. The starter motor for Briggs and Stratton offers a good quality starter. Be mindful that BS has two types of starter – plastic gear head or metal; check before ordering.

Starter – Some starters will have a solenoid and starter motor combined in one unit.

To test, use a jumper lead to bring power from the positive of the battery to the positive post of the starter. If the engine doesn’t crank – Replace the starter.

Common – Most mowers will have the starter and solenoid separate.

Solenoids are fitted to the body, usually under the hood.

Test – Cross a metal screwdriver from one connection to the other, as per the picture.

There will be arcing (sparking) as the screwdriver contacts the poles.

RISK OF FIRE – Keep clear of gasCAUTION THE ENGINE MAY TURN OVER – Place the mower in the park with the parking brake applied and the blade off.

If the engine doesn’t crank over – your starter is faulty; replace it.

Internal Engine Damage

If you’re still reading, I fear the worst has happened. It’s unusual for mower engines to fail completely. They’re generally well-built robust units. I have seen failures like the con rod breaking out through the engine casing; the main bearing seizing; the con rod bending; cylinder head failures.

Some of these faults can be repaired, but most are uneconomic to repair.

New Engine

On the upside, if you have a total failure, a complete engine fully built with a guarantee is available, and fitting involves four bolts, two electrical connectors, a fuel line, a throttle cable, and a crank pulley.

BS and Kohler’s engines are of great quality and ready to go. The completed job will take less than two hours. Be mindful that all engines are shipped without oil.

Failure – Total failure doesn’t happen often.A hard life, and low/poor quality oil, without doubt, increase the chances.

Related Questions

Can you jump-start a mower? A flat or bad battery is a more common fault than a starter. Try jump-starting; if your mower starts, the battery needs attention. If jump starting doesn’t work, investigate a faulty solenoid or starter.

Can a bad alternator ruin a battery? A bad alternator can ruin a battery. Alternators have two main components. A voltage regulator that monitors and controls battery charging and the alternator whose job it is to create voltage. Common problems include a faulty regulator, which damages the battery, and alternator diode failure, which drains the battery.

The Starter Relay and Why a Mower Won’t Start

A lawnmower requires several amperes of electrical current to start the engine. For safety reasons, a lawnmower (and other electric-start internal combustion powered vehicles) contains two parts to the starting circuit: a start switch circuit and a relay circuit. Since an electromechanical relay can only be used for a specified number of cycles before failure, a faulty starter relay can prevent a lawnmower from starting.

Why a Lawnmower Contains a Starter Relay

A relay allows a low-power, light-duty switch to actuate or disengage the starter circuit without being directly wired to the starter circuit itself. If the lawnmower starter circuit did not contain a relay, heavy-duty wiring would have to be wired to the lawnmower starter switch. This would pose a potentially fatal shock hazard if the starter switch or starter circuit wiring became damaged. The starter switch would also be prone to electrical arcing and excessive heat, which would eventually destroy the switch and potentially damage the lawnmower.

  • A lawnmower requires several amperes of electrical current to start the engine.
  • For safety reasons, a lawnmower (and other electric-start internal combustion powered vehicles) contains two parts to the starting circuit: a start switch circuit and a relay circuit.

Why a Bad Relay Prevents a Lawnmower from Starting

When the starter switch is turned on, the switch circuit provides power to an electromagnet inside the relay. This electromagnet pulls the relay switching mechanism closed and engages the relay circuit. The relay circuit provides power from the battery to the starter.

If either the electromagnet or the switching mechanism in the relay is faulty, the relay circuit will not engage. This prevents electrical current from flowing to the starter from the battery.

Why a Bad Switch Prevents a Lawnmower from Starting

Since the switch circuit provides power to the electromagnet in the relay, the switch circuit is just as important as the relay circuit. If the switch is broken, the switch circuit will not provide electrical current to the electromagnet. Without electrical current flowing through it, the electromagnet will not work and the relay cannot be actuated.

  • When the starter switch is turned on, the switch circuit provides power to an electromagnet inside the relay.

Other Considerations

Both the switch circuit and the relay circuit require a power source and transmission lines (wires) to operate properly. If there is a break in the wire on either side of the circuit, or if the power source connection is loose or faulty, this will prevent the lawnmower from starting as well.

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