17 Reasons a Husqvarna Lawn Mower Won’t Start: Starting Problem Solved!

It’s that time of the week when you need to mow your lawn, but this time your mower won’t start. I don’t know about you, but I have a pretty busy schedule and have very few opportunities to get my lawn care done.

A Husqvarna lawn mower won’t start because the engine isn’t getting the air, fuel, or spark required.

This is due to a plugged air filter, dirty carburetor, bad safety switch, faulty gas cap, plugged fuel filter, clogged fuel line, bad starter solenoid, or bad fuel pump.

There are many items on a mower that can fail and cause it not to start. I will share a list of all of the items you should check if you are experiencing a starting issue on a push mower, riding mower, lawn tractor, or zero turn mowers.

Other articles that may help:

• Why your battery keeps dying
• More common problems with riding mowers
• How do you tell if your starter solenoid is bad
• Zero turn mower won’t start

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Troubleshoot a Husqvarna Mower Starting Problem: Fuel, Air, and Spark

An internal combustion engine on a mower requires fuel and air to be introduced to the cylinder. This mixture is compressed and ignited with spark to form combustion.

Check for a Fuel Problem

Old gas is often the root cause for fuel components to stop functioning or for clogs to develop.

Before checking for a fuel problem, if your mower has a fuel shut-off valve, make sure it is in the open position. This valve is often moved to the closed position when the mower is stored or for transportation.

Perform this test to narrow down your problem to the fuel system:

• Detach the air filter cover and remove the air filter.
• Spray carburetor cleaner into the air intake. Find out why I use carburetor cleaner and not starter fluid.
• Attempt to start your mower using the manual recoil starter or turning the ignition key (depending on your mower type)
  • If the mower attempts to start or starts, then you have a problem with the fuel system.
    • The most common fuel issues are a dirty carburetor, a clogged fuel filter, and clogged fuel lines. The fuel pump may also be an issue if your mower uses one.
  • If the mower doesn’t attempt to start, you most likely have a spark plug problem.

Check for an Airflow Problem

Air is an important component needed for your engine to start. The engine must run rich to start a cold engine. This condition allows more fuel and less air into the cylinder.

Airflow is controlled by the choke. You will find a choke lever that opens the choke plate to introduce more air and close the choke plate to restrict air.

On newer Husqvarna push mowers, you will find an automatic choke controlled by a thermostat.

Perform this test to narrow down your problem to the air supply system:

• Detach the air filter cover and remove the air filter.
• Inspect the air filter’s condition. A clogged air filter will restrict airflow. Clean the filter or replace it if it is very dirty or damaged.
• With the air filter removed, inspect the choke plate.
  • Manual-choke model
    • Move the choke lever to the on position: The choke plate should be closed.
    • Move the choke lever to the off position (on some models, this is placing the throttle in the fast throttle position): The choke plate should be open.
  • Auto-choke model
    • The choke plate should be closed when the engine is cold and moved to the open position when the engine warms.
• If the choke isn’t opening and closing correction, check the choke linkage and choke cable. Loosen a stuck choke by lubricating the linkages and choke shaft using carburetor cleaner. Replace a bad choke cable (if used on your model).

Check for a Spark Problem

Spark must be released at the right time for combustion. A spark plug may fail to spark if it is dirty or damaged. It may also fail due to a loose spark plug wire, a bad ignition coil (armature), or other ignition system problems.

Perform this test to narrow down your spark problem:

• Remove the spark plug wire (boot) from the spark plug.
• Attach a spark plug tester to the spark plug ignition wire.
• With the spark plug still installed, attach the other end of the spark plug tester to the spark plug.
• Attempt to start the engine using the pull cord or electric start.
• You will see a glow in the transparent section of the tester if it is generating a spark.
• If you don’t see a glow, the spark plug may be bad or you may have a bad ignition coil. On electric start models, you may have a problem with the ignition system including the battery, wiring, and starter solenoid.

17 Reasons Why a Husqvarna Mower Won’t Start (Starting Problem)

1. Gas Tank is Empty

The most obvious answer to your mower not starting is the lack of fuel. Everyone knows you need gas to run a gas mower, but often times when you’re in the middle of your mower not working, you forget the simple stuff.

FIX: Add fresh fuel to your gas tank.

2. Using the Wrong Type of Gas or Old Gas

Type of Gas

A lawn mower uses unleaded gasoline. The gasoline must have an octane rating of 87 or higher and an ethanol content of 10% or less. Do not use gas with a higher ethanol content as ethanol can cause significant damage to a Husqvarna engine.

The less ethanol your fuel has, the better. Read my article on the type of gas mowers use for more details on choosing the right gas.

Use Fresh Gasoline

Old gasoline running through your fuel system can cause your mower to have many problems including not starting. Gas only has a shelf life of 30 days before it begins to break down and lose volatility.

Ethanol attracts moisture and as it begins to separate, the ethanol and water mixture sinks to the bottom of your tank. This mixture can cause harm to your engine.

In addition to the harm, ethanol can do to your engine, as moisture evaporates, a gummy substance is formed that can clog your fuel system components.

FIX: Drain and flush the fuel tank. Add fresh fuel with a fuel additive to clean your fuel system like Sea Foam.

3. Gas Cap Won’t Vent: Vacuum in the Fuel Tank

The fuel cap has a vent to allow air to pass through the cap. When this vent is plugged, the fuel tank forms a vacuum that doesn’t allow fuel to flow out of the tank.

Therefore, your mower is starved of fuel so it will no longer start.

To determine if the gas cap vent is plugged, remove the cap and start your mower. If your mower starts and runs, place the gas cap back on the fuel tank. Allow the mower to run a little longer to see if it shuts off. If it does, the cap could be your problem.

FIX: Try to clean the cap and open the vent. A thin piece of wire may work to unclog the vent. If you are unable to get the fuel cap to vent, you must replace the gas cap.

4. Bad Spark Plug or Loose Connection

A faulty spark plug that has carbon buildup or oil on the spark plug can fail causing your engine to misfire.  A plug that isn’t properly gapped and has a loose connection can cause starting problems.

FIX: Remove your spark plug and inspect it for signs of carbon buildup or cracked porcelain insulator. Make sure the plug is correctly gapped.

Replace with a new spark plug(s) and securely attach the spark plug wires. A loose wire or a wrong gap can contribute to your starting problem.

5. Clogged Air Filter

Your mower requires air in order to start and run. When air isn’t allowed to pass through the filter because the filter is dirty and plugged, your mower may not start.

If it does start, it may run rough and cause the engine to overheat.

You should periodically check your air filter and keep it clean. This simple procedure can save you from an expensive repair bill.

Clean a PAPER air filter:

• Remove the air filter cover.
• Remove the air filter.
• Remove loose dirt in the air filter housing and from the air filter cover using a clean dry cloth. Be careful and don’t allow dirt to fall into the air intake.
• Tap the air filter element against a solid surface to loosen dirt so it falls out of the filter.
• Hold the filter up to a light source. If you can see good light through the paper, go ahead and continue to use the filter. If you can’t see good light or the filter is damaged, the filter needs to be replaced with a new one.
• Install the new or clean air filter.
• Reattach the air filter cover.

Clean a FOAM air filter:

• Remove the air filter cover.
• Remove the air filter.
• Remove loose dirt in the air filter housing and from the air filter cover using a clean dry cloth. Be careful and don’t allow dirt to fall into the air intake.
• Inspect the air filter for damage. If it is very dark in color, brittle, or has tears in it, it’s time to replace it with a new one. If it is in good condition, continue cleaning the filter.
• Wash the foam filter in water and mild detergent to remove oil and dirt.
• Rinse the filter until it runs clear. Squeeze the filter to remove water. Don’t wring the filter as this can tear it.
• Allow the filter to dry.
• Apply clean engine oil to the filter so it is completely covered. Squeeze excess oil from the filter. (NEVER APPLY OIL to a foam pre-filter. A pre-filter is a filter that wraps around a paper filter element. This can damage the paper filter).
• Install the filter.
• Reattach the air filter cover.

6. Fuel Pump is Bad (Riding Mower, Lawn Tractor & Zero Turn)

A fuel pump is used to move gas to the carburetor. This is required when the fuel tank sits lower than the carburetor.

When the pump is no longer able to draw fuel from the fuel tank using the vacuum of the engine, it must be replaced.

Sometimes you can visibly recognize damage. The housing may have a small crack or fuel may be leaking from the seams when a pump is bad.

Other times you will have to test fuel flow to determine if the fault of your starting problem is due to a bad fuel pump.

FIX: You will need to verify you are getting fuel flow to the fuel pump. Once you confirm you are getting fuel to the pump, you will proceed with testing the pump to make sure a steady or pulsating flow of gas is being pumped out of your fuel pump.

Use the fuel shut-off valve or fuel clamps to start and stop the flow to test fuel flow. Note: some mowers do not have a fuel-off valve.

7. Plugged Fuel Filter

Check your fuel filter. The fuel filter is designed to strain your fuel before it enters your carburetor.

FIX: A cracked fuel filter or plugged fuel filter that doesn’t allow gas to pass through the filter will need to be replaced.

8. Blockage in the Fuel Line  

Deposits from old fuel and dirt can become lodged in your mower’s fuel line. Without a source of gas, because it is being blocked, your is no longer able to start. 

FIX: Remove the fuel line, spray carb cleaner into the tube, and use compressed air to blow air through the tube until the line is free of debris and gummy residue. If you are unable to clear the clog you will need to replace the fuel line.

9. Dirty Carburetor

Your carburetor can become dirty from running old fuel through your lawn mower. Gas can leave deposits in your Husqvarna’s carburetor that can build up so your carburetor is no longer able to function as it is designed to.

A carburetor’s main job is to regulate the amount of fuel mixed with air to form combustion in your engine’s cylinder.

Confirm you are getting gas to the carburetor. Remove the air filter, spray carburetor cleaner into the air intake, and attempt to start the mower.

If the mower starts and then stops once the carburetor cleaner burns, your carburetor might be clogged. Remove the carburetor and clean it.

FIX: If you are a little mechanical you should be able to handle cleaning your carburetor. Clean the carburetor by taking it apart and using carb cleaner to clean the carburetor including the float bowl and needle.

You can find steps for cleaning your carburetor here. If your carburetor is too dirty to clean adequately, you should replace it.

10. Bad Battery, Loose Cables, or Corroded Terminals (Electric Start)

Your mower will not start with a bad battery, loose cables, or corroded terminals. Confirm your battery terminals are not corroded and are attached securely to the battery.

FIX: Clean corroded terminals in a baking soda solution containing 2 cups of water and 3 rounded tablespoons of baking soda. Use a wire brush to scrub the terminals clean.

Test your battery with a multimeter to find if it is fully charged. You need a reading of about 12.7 volts. Place on a charger to charge your battery if your reading is less than this. A weak battery will not provide enough power to turn over and start the mower.

Read more about the steps and items needed to charge your battery here. If your battery does not hold a charge, you will need to replace it with a new battery. 

11. Bad Safety Switch  

Your lawn mower may use several safety switches designed to keep the operator safe. The manufacturer installs safety switches to prevent the mower deck to run without the operator present.

It also has a safety switch involved to not start when your parking break isn’t engaged. If these safety switches fail, your mower may not start.

FIX: Test the switch using a multimeter or you can temporarily bypass the safety switch to identify a bad switch. Do not operate a mower without the safety switch. 

Never run a mower when a safety switch is bypassed. You never know when you will encounter a situation where the safety switch can save you from serious injury.

12. Bad Ignition Switch (Electric Start)

You insert the key into your ignition switch and turn it only to find your mower doesn’t start or even turn over. The ignition switch could be the problem.

FIX: You can use a multimeter to test the ignition switch. Replace the switch if bad.

13. Bad Starter Solenoid (Electric Start)

A Husqvarna starter solenoid is an electromagnetic switch that is like an on-off switch that actuates the starter motor to turn over the engine. A click or hum when turning your ignition key is an indication to check your solenoid.

Another indication your mower solenoid may be bad is when a wire attached to your solenoid gets hot and begins to smoke or melt.

FIX: Test your mower solenoid by following the steps here. Replace your solenoid if it is found to be bad.

14. Bad Recoil on a Push Mower 

Some Husqvarna push mowers use a recoil to start. A recoil can fail due to a bad pulley, a loose or missing spring, or broken clips preventing you from being able to start your mower with the pull of the string.

FIX: You can attempt to replace the spring and restring the recoil. If it does not work because other components in your recoil are damaged such as the clips or the pulley, you are better off just replacing the recoil assembly.

15. Bad Ignition Coil  

The ignition coil provides voltage to the spark plug so it can fire and start the engine. The engine will not start if the spark plug isn’t able to fire.   

FIX: After you verified your spark plug is in good condition, check the continuity of your ignition coil using a multimeter. Replace the ignition coil if you find a break in the continuity.  

16. Faulty Charging System (Riding Mower, Lawn Tractor, Zero Turn)

While the charging system isn’t the main reason your Husqvarna mower won’t start, it can contribute to a weak battery that prevents the mower from starting.

When the charging system fails to charge the battery, the battery may not be able to start the mower the next time you go to use it.

A bad stator or alternator can be a problem. I show steps on how to test your charging system here using an ohmmeter.  

FIX: When you find your starting problem is due to the charging system, take your lawn mower to your local dealer for further troubleshooting and repair.

If you don’t have experience with charging systems, you will most likely just throw different parts at your mower hoping to fix it.

The cost of all of these parts can get pretty expensive if you don’t guess right the first time. Most lawn mower centers do not allow you to return electrical parts so you will be stuck with the part whether it is the problem or not.

17. Incorrect Starting & Operating Procedure  

Husqvarna implements safety precautions with their lawn mowers that require certain steps to be followed when starting and operating the lawn mower.

FIX: Refer to your operator’s manual to ensure you are operating your lawn mower correctly, so you don’t set off the safety features that shut off your lawn mower. 

Husqvarna Starting Problems & Solutions (Quick Reference Chart)

Causes	Solutions
Empty Fuel Tank	Fill with fresh fuel. Husqvarna mowers with 4-cycle engines require a minimum 87-octane rating and maximum 10% ethanol content.
Bad or Old Gasoline	Drain the old fuel. Fill with fresh fuel adding a fuel stabilizer that reduces moisture and cleans the fuel system.
Plugged Air Filter	Clean the filter by knocking dirt out of a paper air filter. If the filter is very dirty, dark in color, wet or damaged, you should replace it with a new filter.
Dirty or Damaged Spark Plug	Clean a dirty spark plug with a wire brush. Replace the plug with a new one if it is very dirty, has broken porcelain, or damaged electrode.
Plugged Fuel Filter	Replace a plugged fuel filter with a new filter. Make sure the arrow on the inline filter is installed and pointed in the direction of the fuel flow.
Plugged Fuel Line	Shut off the fuel supply and remove the fuel line from the mower. Use carburetor cleaner to loosen the clog and compressed air to remove it. Replace a line if you are unable to remove the restriction.
Bad Fuel Pump	Check fuel flow from the pump. Replace a bad fuel pump.
Dirty Carburetor	Remove the carburetor and clean it with a carburetor cleaner. You may need to rebuild it or replace it if cleaning alone does not work.
Bad Safety Switch	Replace a bad safety switch.
Loose or Corroded Cables Connections	Make sure the wires and cables are making a good connection. Remove any corrosion on the terminals and wires.
Weak or Bad Battery	Charge a weak battery. Replace a battery that will no longer hold a charge.
Faulty Ignition Switch	Replace a bad ignition switch.
Plugged or Faulty Fuel Cap	Replace a fuel cap that is no longer venting to allow air to pass to the tank.
Bad Ignition Coil	Replace a bad ignition coil if there is a break in continuity.
Bad Starter Solenoid	Test a starter solenoid and replace it if bad.
Faulty Charging System	If the battery is good and will hold a charge, but the mower continually dies due to a dead battery and will not start, have a mechanic identify whether your problem lies with a component of the charging system.
Incorrect Starting Procedure	Follow starting procedures for the mower as there are safety switches that can prevent the mower from starting if not following the correct steps.

Riding Mower Turns Over but Won’t Start

When you can get the engine to turn over and crank, but it just won’t start, it’s time to look for items that are preventing the engine from getting air, fuel, and spark.

An engine turning over indicates the battery, starter solenoid, and starter motor are working. The cause of your starting issue may be a clogged air filter, bad fuel, a dirty carburetor, or fouled spark plug.

Read More: This is Why a Husqvarna Mower Turns Over and Cranks But Won’t Start.