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 Honda mower from starting. Trying to remember all of them when diagnosing your mower can be difficult especially you’re already upset and not thinking clearly.
A Honda mower won’t start when there is old gas in the fuel system that has clogged components restricting fuel flow. A plugged air filter, bad battery, dirty spark plugs, faulty ignition coil, bad starter solenoid and incorrect operating procedures can also prevent your Honda mower from starting.
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 Honda mower.
15 Reasons Your Honda Lawn Mower Won’t Start
No Gas in the Fuel Tank
Everyone knows a gas-powered Honda lawn mower requires gas to run. When you’re frustrated and just want your mower to start, you can overlook some obvious causes to a starting problem. Check your fuel level and fill with fresh fuel if it is low on fuel.
Fuel Valve on Your Honda Mower 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. Your Honda won’t be able to access fuel if the fuel valve is turned off.
Bad or Old Fuel in Your Honda Mower
Fuel sitting around for a while can become unstable and breakdown causing running issues and gumming in the fuel system. Gummy deposits in the fuel system can clog components restricting fuel required to run. This will prevent your engine from getting the fuel needed to start.
Because fuel can begin to breakdown 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, it reduces moisture and cleans the fuel system.
Drain old fuel from your Honda mower using a fuel siphon. Add fresh fuel with an ethanol content no greater than 10%. Add a fuel stabilizer.
Bad Honda 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 restriction 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. You can attempt to clean your cap to remove the cap or replace it with a new Honda mower fuel cap.
Incorrect Operation of Your Honda Mower
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.
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.
Plugged Honda Mower 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. When you find the filter is plugged, remove it and replace it. Install the new filter with the arrow on the side of your filter pointing in the direction of your fuel flow. The arrow should be pointed toward your carburetor and away from the fuel tank.
Blocked Fuel Line on Your Honda Mower
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. If your Honda mower doesn’t have a valve, crimp your fuel line to stop flow.
Remove the end of a section of 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 your 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 on Your Honda Mower
The carburetor’s function is to regulate the amount of gas mixed with air to form a 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 Honda mower.
If you have verified you are getting fuel to the carburetor, remove the air filter and spray carburetor cleaner into the air intake. Start your mower. If it starts, runs, and then shuts down, take your carburetor apart to clean it. You can find instructions for cleaning your carburetor here.
Plugged Air Filter on Your Honda Mower
A plugged air filter can restrict air flow to the mower and not allow the engine to get the air it needs to form a combustion. It is best practice to replace your air filter annually. Check and clean your air filter regularly.
To clean a paper air filter, remove the filter from the air filter housing. Wipe out loose dirt from the housing. Do not allow dirt to fall into the air intake. Tap the filter against a solid surface to knock dirt from the filter.
Hold it up to a light source and check to see if you can see light shine through the paper. If you see light, go ahead and continue to use the filter. If you do not, replace the air filter. Check out this article on air filters to find cleaning procedures for foam air filters.
Bad or Improperly Gapped Spark Plug on Your Honda Mower
A spark plug can be faulty and fouled when the tip is dirty, the porcelain is cracked or the filament 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.
Your spark plugs must be properly gapped following the manufacturer’s specification as found in your Honda mower operator’s manual. Starting problems can be caused by a spark plug that is gapped incorrectly or loose spark plug wires.
Bad Battery or Blown Fuse on Your Honda Mower
If you use a Honda 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.
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 Honda mower looked at by an experienced mechanic to troubleshoot additional charging problems.
Bad Ignition Switch on Your Honda Mower
You may have a bad ignition switch. You can test it and replace if it is bad.
Bad Ignition Coil on Your Honda Mower
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. Check the continuity of the ignition coil using an ohm meter. If you find a break in the continuity, replace the ignition coil.
Bad Recoil on Your Honda Mower
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.
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 Starter Solenoid on Your Honda Mower
The solenoid on Honda mower is an electromagnetic switch that act 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.
I have listed steps to check your solenoid here. Replace your starter solenoid if you find it to be bad.