Honda Lawn Mower Won’t Start – How To Fix

honda lawn mower won't start

A well-manicured good-looking lawn is a beautiful asset that will improve any house value. Caring for your lawn, and keeping it manicured with your Honda Lawnmower has many other benefits, including creating a sense of pride, keeping the lawn healthy, eliminating pests and preventing invasion, ensuring debris is picked up, and promoting healthy grass.

A non-starting Honda Lawnmower may have

  1. Insufficient Oil
  2. Bad gas
  3. Clogged air filter
  4. Fuel valve or choke problem
  5. Damaged HT lead
  6. Faulty plug
  7. Faulty or gummed up carburettor
  8. Faulty coil
  9. Bail lever/ignition fault
  10. Bad flywheel timing
  11. Sticking valve or insufficient compression

Depending on the condition of your Honda lawnmower, the reason why it is not starting could be straightforward to fix.

Start with the simple checks before attempting to diagnose the more complex possibilities.

How To Fix A Non-Starting Honda Lawnmower?

Combustion engines need three things to make them work.

  1. Enough clean gas
  2. Enough Air
  3. A sufficient correctly times spark creates the explosion to compress the air in the cylinder chamber to force the piston down.

If any of these are missing, it doesn’t matter how many times you pull the starter cord or press the starter button; the engine will not fire.

In the following section, we will look at each issue, the problem it may cause, and the solution. We have assigned a score from 1-3 (1 = low, 2 = Simple, 3 = complex), representing the difficulty each one is to fix.

The Honda Lawnmower Has Insufficient Oil – Score 1

Most four-stroke Honda Lawnmowers have a safety switch that will not allow the engine to be started unless there is sufficient oil.

Check the oil level according to the manufacturer’s manual, and if necessary, fill the oil tank with the required amount of oil.

The Fuel Tank Is Empty, Or The Gas Is “Bad” – Score 1

Check if the tank has sufficient gas. You will be surprised how often users assume the tank is full when it isn’t.

If the Honda lawnmower has not been started for a while, possibly after being stored up for winter, the gas may become stale or gummy.

After the gas is left for a period, it begins to form carboxylic acid and gum, making it degrade. The more it loses its consistency, the less chance it will fuel the ignition.

Hot Tip! Don’t leave the Honda Lawnmowers fuel tank full over winter.

Doing so reduces the chance of the Honda lawnmower starting, and the carboxylic acid damages the soft rubber components in the fuel system and makes them stiff and inflexible.

If there is insufficient fuel, fill the tank.

If the fuel is old and stale, empty the tank and refill it with fresh gas.

The Honda Lawnmowers Air Filter May Be Blocked – Level 1

If the air filter is filthy, insufficient air prevents the ignition sequence.

A symptom of a dirty air filter is that the Honda Lawnmower may start briefly but does not run consistently.

Loosen the air filter box and remove the filter.

Replacement units are not expensive, and rather than trying to clean the filter, we suggest you buy a new one and replace this.

The Gas Tap Is Switched Off – Level 1

Directly under the fuel tank, you will find a rotating tap with the words on/off printed.

If the Fuel Tap is in the off position, turn it to the “on” position, and the Honda Lawnmower should start.

The Honda Lawnmower Choke Is Not On – Level 2

The choke changes the fuel/oil mixture when the lawnmower is cold. The choke restricts the amount of air sent to the piston chamber.

Older Honda lawnmowers had a manual choke lever, whereas modern units have an automated choke. To check if the system is working correctly, follow the following steps.

Step One – Find the Air Filter

Identify the air filter box situated on the front left side of the engine (seen from the back).

Step2 – Take The Air Filter Off

Before starting the engine (i.e., when it is still cold), unclip the air cleaner cover and remove the filter element. Look inside the opening and check if the choke flap is completely closed.

Step 3 – Check The Condition Of The Thermal Wax Cartridge

A common reason for the choke flap being open is the thermal wax cartridge (part no 16620-Z8D-305) is sticking.

  1. To replace this part, undo the two long screws in the air filter box.
  2. The airbox will come off.
  3. Pull the carburettor a little way from its mounting point, and the plastic mounting plate behind the carburettor will come off.
  4. Take note of the position of all the gaskets.
  5. About one inch above the carburettor opening, you will see a small, bullet-shaped component supported by a rubber gasket. The part is the thermal wax cartridge.
  6. Using a pair of needle nose plyers, gently remove the cartridge. If a pin sticks out of the back of the cartridge, it is faulty.
  7. To install the new cartridge, reverse the above steps.

The Honda Lawnmowers Ignition System May Be Faulty Level 1-3

The ignition system consists of the

  1. HT Leads
  2. Spark Plug
  3. Coil
  4. Flywheel

If the ignition system is faulty

  1. The engine won’t fire.
  2. The engine only starts after repeated attempts
  3. The lawnmower seems to be less powerful.
  4. The lawnmowers fuel consumption is increased.

The Honda Lawnmower May Have A Damaged HT Lead – Level 1

The following may indicate a damaged HT Lead:

  • Check the lead which attaches to the end of the spark plug.
  • Make sure the lead is not disconnected.
  • If the Honda Lawnmower still does not start, you may have a damaged lead.
  • Check that the lead is securely attached to the spark plug boot. To fix this, place the wire back into the boot and crimp the connection with a pair of plyers.

The Honda Lawnmowers Spark Plug May Be Faulty Level 1

It is easier to purchase a new one without going into a long technical article about checking and testing the spark plug.

  1. Unplug the spark plug lead from the existing plug and unscrew it.
  2. Screw the new plug into the socket, making sure you screw it in tightly but not too much. If you do tighten it too much, you risk stripping the threads.

The Honda Lawnmower Has A Faulty Coil – Level 2

The Honda ignition coil transforms the voltage produced by magnets on the flywheel into the thousands of volts the spark plug needs to ignite the fuel.

If you have checked the spark plug and leads and there is still no spark, the coil may be faulty.

The procedure to check the coil’s function is.

  1. Attach the spark tester to the ignition cable
  2. Attach the other end of the spark plug tester to a bolt or fin on the cylinder head.
  3. Make the engine turnover by pulling the cord or turning the starter motor over and looking for a spark in the spark plug tester.
  4. If there isn’t a spark, you may have a damaged coil. Don’t try to fix it and instead buy a new one.

The procedure to replace the coil is.

  1. Unplug the spark plug lead and close the petrol tap.
  2. Unscrew the nuts securing the recoil starter.
  3. Remove the starter unit.
  4. Remove the lawnmower shroud and tank, being careful not to spill fuel.
  5. Disconnect the engine shut-off wire from the coil.
  6. Use a 10mm spanner to remove the coil mounting bolts.
  7. Replace the ignition coil and reverse the steps to reinstall it.

Your Lawnmower Has A Faulty Carburettor – Level 3

When the piston reaches the top, the carburettor mixes the fuel and air in the correct portions and squirts the mixture into the top of the piston chamber.

If the fuel is old and gummy, it is possible that the carburettor is blocked and is not allowing the correct mixture into the chamber.

If you suspect the carburettor, we recommend that you get a professional lawnmower technician to fix the problem,

If It Isn’t Fixed, The Fault May Be More Serious  – Level 3

Other problems preventing Honda Lawnmower from starting may include.

  1. Bad flywheel timing
  2. A sticking valve
  3. Insufficient compression

If the Honda lawnmower is still not starting, you should have a lawnmower technician check these issues.


Honda lawnmowers use straightforward but clever technology to provide the customer with a reliable, easy-to-use lawn cutting machine.

It is not hard to check most of the problems which may go wrong, and we encourage you to give it a go.


This is the site where I share all of the information about home security. I have been working in this industry from last 10 years and therefore, sharing all my experiences and learnings.

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