Honda generators won’t start when there isn’t sufficient air, spark, and fuel.
This may be due to a lack of fuel, plugged fuel filter, clogged fuel line, dirty carburetor, plugged air filter, clogged spark arrestor, bad spark plug, faulty ignition coil, bad gas cap, or low engine oil level.
Honda generators with an electric start may have a bad battery, bad ignition switch, or faulty starter solenoid preventing it from starting.
To minimize injury, follow the safety precautions outlined in the Honda operator’s manual. This includes removing the spark plug wire and waiting for the engine to cool before performing repairs.
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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.
Reasons Your Honda Generator Won’t Start
Empty Fuel Tank
You know your Honda generator requires gas to run, but you may have developed a leak or just forgotten to fill the fuel tank.
I only mention this obvious reason for your generator not starting because, sometimes out of frustration, owners forget to check the fuel tank before they begin addressing other items on the generator.
SOLUTION: Add fresh fuel to the fuel tank. Honda generators with 4-cycle engines require gasoline. Honda generators with 2-cycle engines require a gas and oil mixture in the fuel tank.
Bad or Old Fuel
You may not realize that gas can begin to break down and become less effective as soon as 30 days after purchase. Not only does it begin to break down, but ethanol also attracts moisture to the fuel system.
Ethanol is an alternative fuel that is environmentally friendly because it is often made from corn or another high-starch plant. The ethanol and moisture it attracts leave behind varnish and gummy deposits that can cause component failures and fuel restrictions.
Because of the adverse effects ethanol has on a Honda generator, it’s important to keep these things in mind when purchasing, storing, and consuming fuel:
- Purchase fresh fuel with a minimum 87 octane rating (91 RON).
- Never use gas with more than a 10% ethanol content. Low ethanol and ethanol-free fuel are best.
- Consume fuel within 30 days.
- Use a fuel stabilizer if you are unable to consume it within 30 days to make it last a little longer before breaking down. (Fuel stabilizer must be added to fresh fuel. It will not reverse the effects of old fuel).
- Store fuel in an approved fuel container away from moisture or combustible products.
SOLUTION: If you find old fuel in your Honda generator, drain the fuel using a fuel siphon pump. Mix fresh gas with a fuel additive to help clean the fuel system, reduce moisture and stabilize the gas.
Add gas to the fuel tank. Once you are able to get the generator to start, allow it to run for about 15 minutes so the gas and stabilizer mixture is able to work its way through the fuel system.
I like a product called Sea Foam Motor Treatment. I use this product in every tank of gas to help reduce the issues that can result from using fuel with ethanol. Another good option is STA-BIL.
***NOTE: If you use a Honda generator with a 2-cycle engine, you must use a gas and oil mixture in the fuel tank. DO NOT add straight gas to a 2-cycle engine.
Plugged Fuel Filter
Check the fuel filter on the generator. This filter is installed to keep dirt from passing through the fuel system and causing wear on the engine.
When the filter isn’t regularly replaced, it can become so clogged with dirt and deposits that a good flow of fuel isn’t able to pass through the filter. This lack of fuel will cause the generator not to start.
For the average homeowner, I recommend replacing the fuel filter annually. You may have to replace it more often if you run the Honda generator regularly.
SOLUTION: Replace a plugged Honda fuel filter.
Clogged Fuel Line
The sticky deposits left behind by old fuel can clog the fuel lines. Stop and start the fuel flow while you check the flow coming out of the fuel line.
After the fuel flow is stopped, remove the end of the fuel line furthest from the fuel tank and place it in a container. Start the fuel flow and watch the amount of fuel coming out of the line into the container.
This container must be placed lower than the fuel tank because fuel cannot run uphill without the assistance of a pump.
SOLUTION: If you find a restriction in the fuel line, turn off the fuel flow, and remove the line from the generator. Spray carburetor cleaner to loosen the clog and blow compressed air to the line to remove it.
If you are unable to remove the fuel restriction or you find the line is dry or cracked replace it with a new fuel line of the same diameter and length.
Bad Carburetor
A Honda generator uses a carburetor to regulate the amount of gas that is mixed with air to form combustion in the engine cylinder.
When the carburetor is dirty due to varnish buildup from old fuel, components in the carburetor will fail to function properly. The engine may not get the gas required to start your generator when the fuel jet is plugged or the float or float needle is stuck.
Before you start tearing apart the carburetor to clean it, make sure you are getting sufficient fuel to the carburetor. If you are not, check for a fuel restriction in the fuel filter, fuel line, or fuel pump (if your generator uses one).
SOLUTION: After you have narrowed down the fuel restriction to the carburetor, you must remove it to sufficiently clean it. Use carburetor cleaner to remove as much buildup as possible.
Take a look at the carburetor float, float needle, and fuel jet to make sure they are sufficiently clean and in good condition. If you find any damaged parts, you must replace them using a carburetor rebuild kit or a replacement carburetor.
Plugged Air Filter
The air filter protects the engine by filtering the air to keep dirt and debris from entering the air intake. A plugged air filter will restrict the amount of air being mixed with gas for combustion.
The air filter should be replaced annually and more often if you are running the Honda generator in dusty conditions. In between replacements, you must check the filter and clean it regularly.
If you are not cleaning and replacing the filter regularly, the filter can become plugged with so much dirt that the engine won’t get sufficient air and may not start. If it does, the engine can overheat and cause extensive permanent damage.
SOLUTION: If you find your air filter is plugged, you must clean it using the procedure below for a foam air filter. If you are unsure of the type of filter you have and its cleaning procedure, consult the operator’s manual.
Clean a Honda generator foam-style 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.
- Saturate the filter in clean engine oil so it is fully covered. Then squeeze the filter to remove excess engine oil.
- Install the air filter.
- Reattach the air filter cover.
Plugged Fuel Tank Vent
The fuel tank must be able to vent. Honda generators build the fuel tank vent into the fuel cap. This allows air to pass through the cap.
Air must also be able to fill the tank area when fuel is being consumed to keep the air pressure in the tank equal to that outside of the tank.
When air isn’t allowed to pass through the gas cap due to a plugged vent, the fuel tank will form a vacuum. This prevents fuel from getting to the carburetor and your generator will fail to start.
If your Honda’s fuel cap has a lever on the cap showing an on/off position, make sure the lever is placed in the on position when starting and running the generator.
SOLUTION: To determine whether your cap is the cause of your starting problem, loosen or remove the cap to allow air inside the tank and then attempt to start the generator.
If it starts, but stops running again after you place the cap back on the generator and allow it to run for a while, you may have a problem with the cap. I recommend replacing a bad gas cap.
Plugged Spark Arrestor
The spark arrestor screen is a metal piece on the muffler that prevents sparks and hot material from emitting from the muffler. This screen is required to prevent injuries and fires.
When it becomes plugged, the generator will have a hard time starting and running due to clogged exhaust.
SOLUTION: Remove the spark arrestor screen from the muffler. Take a look at it to ensure it isn’t torn and doesn’t have any holes in the screen. If it does, the screen must be replaced with a new one.
If it doesn’t have any damage, go ahead and clean it with a commercial solvent or brush it lightly with a small metal brush to remove soot deposits. Once clean, reinsert the screen back onto the muffler.
Bad Spark Plug
A spark plug can be faulty when the tip is dirty, the porcelain is cracked or the electrode is burnt. This will cause a Honda generator not to start because of a lack of spark.
SOLUTION: You can clean the spark plug to remove the deposits on the tip. If your spark plug tip is very dark in color or damaged, you must replace it with a new one.
The spark plug needs to be properly gapped following the manufacturer’s specifications as found in the operator’s manual. Starting problems can be caused by a spark plug that is gapped incorrectly or a spark plug wire that is 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 due to a bad spark plug or ignition coil, the engine will not start.
SOLUTION: Check the continuity of the ignition coil using an ohm meter. If you find a break in the continuity, replace the ignition coil.
Incorrect Engine Oil Level
A Honda generator may have a low engine oil sensor that will shut off the generator and not allow it to start. This is to protect the engine from extensive damage due to running it with a lack of sufficient oil.
If your generator doesn’t have a low engine sensor and has been run low on oil, it may no longer start because of damage.
Oil provides the lubrication needed for the internal engine parts to move freely. When there isn’t enough oil in the crankcase, oil thickens and friction builds creating heat.
SOLUTION: Check the engine oil level by placing the generator on a flat-level surface. Remove the oil fill cap and wipe off the dipstick with a clean cloth to remove the oil.
Reinsert the dipstick into the oil-fill tube, but don’t screw on the cap. Remove it and look at the oil level on the dipstick. Ensure it is in the full range on the dipstick.
If it is not, correct the engine oil level by removing or adding a little oil until it is at the correct level.
When you find you have the correct engine oil level and the low oil sensor stays on, you may have a faulty sensor. It’s best to take the generator to a service center to be repaired.
If your Honda generator doesn’t have a low oil sensor or the sensor failed and you find the oil is low and it won’t start after correcting it, you may have caused engine damage. This is also something you should take to a small engine service center for accurate diagnosis.
Incorrect Choke Setting or Stuck Choke
The choke is required to restrict airflow to start a cold engine on a Honda generator or it won’t start.
Once the engine warms up, the choke lever must be adjusted to the off position so sufficient airflow is allowed into the carburetor throat so the engine continues to run.
When the choke is placed in the correct position and you continue to have airflow problems, check the choke linkage to make sure it is not stuck and is opening and closing correctly.
Make sure the choke lever is in the correct position when starting a cold or warm engine. If you find the choke is stuck, use carburetor cleaner to help free it up so it moves without sticking.
Bad Recoil on a Manual Start Generator
When the starter recoil wears or parts of the recoil break, it’s hard or impossible to get the generator started. The rope on the recoil can become unstrung or the pulley, springs, or clips may break causing your starting problems.
SOLUTION: Sometimes, restringing the recoil is all you need. Other times you will have to replace broken parts in your recoil. Before replacing parts, 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 (Electric Start)
Make sure the battery is charged. If it has a low charge, you can attempt to charge the battery. If it won’t hold a charge, it’s time to replace the battery with a new one.
Check the cables and wiring to make sure you have good continuity and making good connections.
SOLUTION: Check the voltage of the battery and charge it if it is weak. Replace a dead battery or one that won’t hold a charge.
Bad Ignition Switch (Electric Start)
The switch can go bad on a generator with an electric start preventing it from starting.
SOLUTION: Test the switch using a multimeter and replace it if necessary.
Bad Starter Solenoid (Electric Start)
You may hear a clicking or humming sound when you press the ignition switch button or turn the key (depending on your model) and your generator won’t start. Or, you may find the wiring is getting hot and beginning to smoke.
These are indications the solenoid may be bad. A starter solenoid goes bad when the internal spring gets weak or the copper plate begins to corrode. A weak starter, bad battery, or bad ground can also be the reason for the solenoid failure.
SOLUTION: You can attempt to bypass the starter using a screwdriver or pliers by touching the cable from the battery and the cable to the starter. Be careful as it may throw a spark.
If the engine turns over with the solenoid bypassed, it is likely the starter solenoid is bad.
You must check for loose wires or bad ground before replacing the solenoid. These are items that can cause the solenoid to not work correctly.
The good news is most portable Honda generators with an electric start have a manual starter recoil installed to pull-start it to get it running. If you are able to manually start it, you can narrow down your problem to the electric start system.