It can get pretty frustrating when you finally find time to mow your lawn only to find your mower won’t start. There are so many things that can prevent your mower from starting.
Trying to remember all of them when diagnosing your mower can be difficult especially if you’re already upset and not thinking clearly.
A Honda lawn mower won’t start due to a plugged air filter, wrong choke setting, bad spark plug, faulty ignition coil, plugged fuel filter, clogged fuel line, dirty carburetor, or old gas.
Check the battery, starter, and ignition switch on electric start models.
Keep reading for a full list of items that can cause your starting problem. Make sure you follow all safety guidelines in your owner’s manual before performing work on your mower.
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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.
15 Reasons Your Honda Lawn Mower Won’t Start
No Gas in the Fuel Tank
Everyone knows a gas-powered lawn mower requires gas to run. When you’re frustrated and just want your mower to start, you can overlook some obvious causes of a starting problem.
Also, check for a faulty fuel gauge or fuel leak that may have you refilling your fuel tank sooner than you expected.
SOLUTION: Check your fuel level and fill it with fresh fuel if it is low on fuel. Repair a fuel leak or a faulty fuel gauge.
Fuel Valve is in the Off Position
Check to make sure the fuel valve is not shut off and remains in the on position. You may have shut the valve off when working on the fuel system or while storing your mower.
SOLUTION: Your Honda won’t be able to access fuel if the fuel valve is turned off. Confirm the valve is in the on/open position.
Bad or Old Fuel
Fuel sitting around for a while can become unstable and break down causing running issues and gumming in the fuel system.
Gummy deposits in the fuel system can clog components restricting the fuel required to run. This will prevent your engine from getting the fuel needed to start.
Because fuel can begin to break down as soon as 30 days after purchase, use your fuel within this time frame or add a fuel additive to stabilize your fuel so it lasts longer.
I use a product called Sea Foam Motor Treatment. It not only stabilizes fuel but also reduces moisture and cleans the fuel system.
SOLUTION: Drain old fuel from your mower using a fuel siphon pump. Add fresh fuel with an ethanol content no greater than 10% with a fuel additive mixed in to keep the fuel stable and help reduce moisture.
Bad Mower Fuel Cap
A fuel cap is vented to allow air to pass through the cap. When the vent in the cap becomes clogged, your fuel tank will not be able to vent causing it to form a vacuum restricting fuel from flowing out of the tank.
Run your mower with and without the fuel cap. If it starts without the cap but eventually shuts down after replacing the fuel cap, you may have a cap that cannot vent.
SOLUTION: Replace the gas cap with a new fuel cap.
Incorrect Starting Procedure and Operation
Honda push mowers use a blade control lever as a safety feature on the mower. This is a safety procedure that will prevent the mower from running when the operator is no longer present.
The blade control lever must be pulled back and held against the handlebar to start and run the mower.
SOLUTION: Make sure the blade lever is held against the handlebar while turning the ignition key on an electric start mower or pulling the recoil on a manual start mower.
When the blade control lever is released, the engine will stop and the blades will not continue to turn.
Clogged Fuel Filter
The fuel filter strains your fuel to prevent dirt from entering the fuel system and your engine causing damage. The fuel filter can become so plugged that fuel isn’t allowed to pass.
SOLUTION: When you find the filter is plugged, remove it and replace it. Check to see if the filter has an arrow on the side of the housing. Install the new filter with the arrow pointing in the direction of your fuel flow.
The arrow should be pointed toward your carburetor and away from the fuel tank.
Clogged Fuel Line
Dirt and deposits formed from running old fuel can cause a blockage in the fuel line. Check the fuel line by stopping your fuel flow using the fuel shut-off valve.
SOLUTION: Check the fuel line by stopping your fuel flow using the fuel shut-off valve. If your mower doesn’t have a valve, clamp the fuel line to stop the flow.
- Remove the end of a section of the hose furthest from your fuel tank and place it in a container.
- Start your fuel flow and make sure you are getting fuel into the container.
- The container must be placed lower than the fuel tank. Fuel cannot run uphill.
- If you don’t get a good flow of fuel out of the fuel line into the container, stop the fuel flow and remove the fuel line from your mower.
- Spray carburetor cleaner in the line to loosen up the clog.
- Use compressed air to blow through the line to remove the blockage.
- If you cannot free the line of the clog, replace it with a new fuel line.
Bad Carburetor
The carburetor’s function is to regulate the amount of gas mixed with air to form combustion in the cylinder. When the carburetor is dirty and gums up from old fuel, components in the carburetor no longer function properly.
The carburetor may not allow the release of gas required to start your mower. If you have verified you are getting fuel to the carburetor, remove the air filter and spray carburetor cleaner into the air intake.
SOLUTION: Start your mower. If it starts, runs, and then shuts down, you need to disassemble the carburetor to clean it. You can find instructions for cleaning your carburetor here.
Plugged Air Filter
A plugged air filter can restrict airflow to the mower and not allow the engine to get the air it needs to form combustion. It is best practice to replace your air filter annually.
SOLUTION: Check and clean your air filter regularly. Replace the filter when it is very dirty or damaged.
Clean a PAPER air filter:
- Remove the air filter from the housing.
- Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
- Inspect the paper air filter. Tap the filter to loosen dirt so it falls from the filter.
- Hold the air filter up to a light source. If you can see good light go ahead and reuse it. If you are not getting good light or it is very dirty, damaged, or no longer seals the air intake sufficiently, replace it with a new one.
- Install the air filter.
- Reattach the air filter cover.
Clean a FOAM primary air filter
- Remove the air filter from the housing.
- Wipe out any dirt remaining in the air filter housing and cover. Don’t allow dirt to fall into the air intake.
- Inspect the foam filter for damage and replace it if needed.
- If the filter is in good condition, clean it in soapy water and rinse it until the water runs clear.
- Squeeze the filter and allow it to dry.
- Lightly saturate the foam filter in clean engine oil. Squeeze to remove excess oil. (Note: Don’t add oil to a pre-filter used with a paper air filter. This will damage the paper filter). Consult your operator’s manual if you are unsure what fluid you should use for your model to coat the filter.
- Install the air filter.
- Reattach the air filter cover.
Bad or Improperly Gapped Spark Plug
A spark plug can be faulty and fouled when the tip is dirty, the porcelain is cracked or the electrode is burnt.
You can clean the spark plug to remove the deposits on the tip. If your spark plug tips are very dark in color or damaged, you must replace your spark plug.
SOLUTION: Your spark plugs must be properly gapped following the manufacturer’s specifications as found in your Honda mower operator’s manual.
Starting problems can be caused by a spark plug that is gapped incorrectly or spark plug wires that are loose.
Bad Ignition Coil
Before checking for a bad ignition coil, make sure your spark plug is in good condition. The ignition coil provides voltage to the spark plug so it can start the engine.
If the spark plug isn’t able to fire, the engine will not start.
SOLUTION: Check the continuity of the ignition coil using an ohmmeter. If you find a break in the continuity, replace the ignition coil.
Bad Recoil
The recoil on your mower may no longer be able to start your mower. A rope on the recoil can become unstrung or you may find you have a broken pulley, springs, or clips in your recoil that need to be repaired.
SOLUTION: Sometimes, restringing the recoil is all you need. Other times you will have to replace broken parts in your recoil. Before doing this, price out a full recoil replacement.
Depending on the price difference, it may be better to replace the recoil assembly over tearing it down and replacing broken components.
Bad Battery or Blown Fuse (Electric Start
If you use a mower with an electric start, the battery may be bad or it might not have a sufficient charge to start your mower.
Try to start your mower with the manual recoil. If the mower starts with the recoil, you have a problem with the electric start.
SOLUTION: Charge your battery using the battery charger. Plug the charger into the port connector on the handle closest to the battery.
Charge by plugging it into a 120-volt outlet. The battery charger is an optional piece for most Honda mowers.
If the battery fails to charge, check the fuses. There should be 2 fuses. When the larger amp fuse is bad, the electric starter will fail to work. When the lower amp fuse is bad, the battery will not charge. If the fuses are fine, replace the battery.
If it still doesn’t charge, have your mower looked at by an experienced mechanic to troubleshoot additional charging issues.
Bad Ignition Switch (Electric Start)
You may have a bad ignition switch.
SOLUTION: You can test it using a multimeter and replace it if it is bad.
Bad Starter Solenoid (Electric Start)
The starter solenoid is an electromagnetic switch that acts like an on-off switch that actuates the starter motor to turn over the engine.
If you hear a click or hum when turning the ignition key or the wires attached to your solenoid get hot and begin to smoke, you need to test the solenoid.
SOLUTION: I have listed steps to check your solenoid here. Replace your starter solenoid if you find it to be bad.