9 Fixes For When Your Lawn Mower Won’t Start. Carburetor for Honda mower

Avoiding Fuel-Related Problems

Your Honda lawn mower is designed and manufactured to precise specifications to ensure years of troublefree operation. This includes the fuel system. However, the properties of gasoline can quickly lead to stale fuel causing starting or running problems and, in some cases, damage to the fuel system if precautions are not followed. The good news is most fuel-related problems can be avoided by following a few simple steps. The steps shown below are also recommended for Honda-powered lawn mowers.

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Follow These Five Steps to Prevent Most Fuel-Related Problems

Do not use gasoline containing more than 10% ethanol in your Honda lawn mower.

Gasoline containing higher levels of ethanol is corrosive and attracts water, which can cause starting or running problems or, in some cases, damage to your lawn mower’s fuel system.

Store your gasoline in a clean, plastic, sealed container approved for fuel storage. Close the vent (if equipped) when not in use and store the container away from direct sunlight. If it takes more than 3 months to consume the fuel in the container, we suggest adding a fuel stabilizer to the fuel when you fill the container.

A clean, plastic container approved for fuel storage will help prevent rust and metallic contaminants from entering the fuel system. Gasoline will deteriorate faster when exposed to air and sunlight.

Keep your lawn mower’s air filter properly serviced. Check it before each use.

A properly maintained air filter will help prevent dirt from entering your lawn mower’s carburetor. Check the filter before each use. Replace it often when used in dusty conditions. Dirt entering the carburetor can be drawn into small passages in the carburetor and premature engine wear. These small passages can become blocked, causing starting or running problems. Always use a Honda Genuine air filter to ensure the air filter seals and performs as designed.

When you’re finished mowing, turn the fuel valve OFF and leave it OFF until you’re ready to mow again. Fill the fuel tank to minimize air in the tank. If you do not intend to use your mower for 3 to 4 weeks, start the engine with the fuel valve OFF, and allow it to run until the engine runs out of gas.

The small amount of gasoline in your lawn mower’s carburetor will deteriorate faster than the fuel in the fuel tank due to its small volume and proximity to residual engine heat. The fuel valve allows you to stop the fuel flow from the fuel tank to the carburetor for storing and transporting.

Filling the fuel tank after each use (instead of before each use). If the fuel tank is partially filled, air in the tank will promote fuel deterioration.

If you don’t plan to use your lawn mower for more than 30 days, follow the storage guidelines below.

Untreated gasoline (without a fuel stabilizer) left in the lawn mower’s fuel system will deteriorate, causing starting or running problems and, in some cases, damage to the fuel system.

Refer to your lawn mower’s Owner’s Manual for additional information. If you do not have an owner’s manual, you can download the manual here.

Storing Your Lawn Mower for Than 30 Days

If you don’t plan to use your lawn mower for more than 30 days, follow these steps to reduce fuel-related problems.

Storage Time: 30 to 90 days

• Add gasoline stabilizer to the fuel tank following the manufacturer’s instructions. When adding a gasoline stabilizer, fill the fuel tank with fresh gasoline. If only partially filled, air in the tank will promote fuel deterioration during storage. Note:
• All stabilizers have a shelf life, and their performance will deteriorate over time.
• Fuel stabilizers will not reconstitute stale fuel.
• After adding a gasoline stabilizer to the fuel for the first time, run the engine outdoors for 10 minutes to be sure the treated gasoline has replaced the untreated gasoline throughout the fuel system. If you regularly add fuel stabilizer to your storage container when refilling, you may skip this step.
• Stop the engine and turn the fuel valve to the OFF position.
• Restart the engine and allow it to run until it runs out of gas. Running time should be less than 3 minutes.

After adding a gasoline stabilizer to the fuel for the first time, run the engine outdoors for 10 minutes to be sure the treated gasoline has replaced the untreated gasoline throughout the fuel system. If you regularly add fuel stabilizer to your storage container when refilling, you may skip this step.

Stop the engine and turn the fuel valve to the OFF position.

Restart the engine and allow it to run until it runs out of gas. Running time should be less than 3 minutes.

Storage Time: than 90 days (long term or seasonal storage)

Start the engine and allow it to run long enough to empty all the gasoline from the entire fuel system (including the fuel tank). Do not allow gasoline to remain in your lawn mower for more than 90 days of inactivity.

Stale fuel in your fuel container

If you have some fuel left in your storage container at the end of the season, the Environmental Protection Agency (EPA) suggests adding the gasoline to your car’s gas tank provided your car’s fuel tank is fairly full and the fuel is appropriate for your vehicle.

There are a number of reasons, mechanical and otherwise, why a mower won’t run. The good news is that fixing most all of the issues is easy enough for a DIYer to handle.

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Lawn care can be tedious, but once the grass starts growing in the spring, mowing becomes a fact of life in most neighborhoods. When you finally muster the strength to tackle that first cut of the season, there are few sounds as disheartening as that of a lawn mower engine that turns over but doesn’t start.

Before you drag the mower in for repairs or invest in costly replacement parts, first make sure that a clogged air filter, soiled spark plug, damaged safety cable, clogged mowing deck, or contaminated gas isn’t to blame. Work through the following steps, and you may be able to get your puttering grass guzzler up and running again in no time.

A lawn mower repair professional can help. Get free, no-commitment repair estimates from pros near you.

Change the lawn mower carburetor filter.

Your lawn mower’s air filter guards the carburetor and engine from debris like grass clippings and dirt. When the air filter becomes clogged or too dirty, it can prevent the engine from starting. To keep this from happening, replace paper filters—or clean or replace foam filters—after every 25 hours of engine use.

The process for removing the filter depends on whether you are operating a riding or walk-behind lawn mower. For a riding mower, turn off the engine and engage the parking brake; for a walk-behind mower, pull the spark plug wire from the plug. Then, lift the filter from its housing.

The only choice for paper filters is replacement. If you’re cleaning a foam filter, wash it in a solution of hot water and detergent to loosen grime. Allow it to dry completely, and then wipe fresh motor oil over the filter, replace it in its housing, and power up the mower—this time to the pleasant whirring of an engine in tip-top condition.

Check the spark plug.

Is your lawn mower still being stubborn? The culprit may be the spark plug, which is responsible for creating the spark that ignites the fuel in the engine. If it’s loosened, disconnected, or coated in water or carbon residue, the spark plug may be the cause of your machine’s malfunction.

Locate the spark plug, often found on the front of the mower, and disconnect the spark plug wire, revealing the plug beneath. Use a socket wrench to unscrew the spark plug and remove it.

Check the electrode and insulator. If you see buildup, spray brake cleaner onto the plug, and let it soak for several minutes before wiping it with a clean cloth. Reinstall the spark plug, first by hand, and then with a socket wrench for a final tightening. If the problem persists, consider changing the spark plug.

Clear the mower deck of debris.

The mower’s deck prevents grass clippings from showering into the air like confetti, but it also creates a place for them to collect. Grass clippings can clog the mower deck, especially while mowing a wet lawn, preventing the blade from turning.

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If the starter rope seems stuck or is difficult to pull, then it’s probably due to a clogged deck. With the mower safely turned off, tip it over onto its side and examine the underbelly. If there are large clumps of cut grass caught between the blade and deck, use a trowel to scrape these clippings free. When the deck is clean again, set the mower back on its feet and start it up.

Clear the vent in the lawn mower fuel cap.

The mower started just fine, you’ve made the first few passes, then all of a sudden the mower quits. You pull the cord a few times, but the engine just sputters and dies. What’s happening? It could have something to do with the fuel cap. Most mowers have a vented fuel cap. This vent is intended to release pressure, allowing fuel to flow from the tank to the carburetor. Without the vent, the gas fumes inside the tank begin to build up, creating a vacuum that eventually becomes so strong that it stops the flow of fuel.

To find out if this is the problem, remove the gas cap to break the vacuum, then reattach it. The mower should start right up. But if the lawn mower won’t stay running and cuts off again after 10 minutes or so, you’ll need to get a new gas cap.

Clean and refill the lawn mower fuel tank.

An obvious—and often overlooked—reason your mower may not be starting is that the tank is empty or contains gas that is either old or contaminated with excess moisture and dirt. If your gas is more than a month old, use an oil siphon pump to drain it from the tank.

(It’s important to be careful as spilled oil can cause smoking, but there are other reasons this might happen. Read more about what to do when your lawn mower is smoking.)

Add fuel stabilizer to the tank.

Fill the tank with fresh fuel and a fuel stabilizer to extend the life of the gas and prevent future buildup. A clogged fuel filter is another possible reason for a lawn mower not to start. When the filter is clogged, the engine can’t access the gas that makes the system go. If your mower has a fuel filter (not all do), check to make sure it’s functioning properly.

First, remove the fuel line at the carburetor. Gas should flow out. If it doesn’t, confirm that the fuel shutoff valve isn’t accidentally closed. Then remove the fuel line that’s ahead of the fuel filter inlet. If gas runs out freely, there’s a problem with the fuel filter. Consult your owner’s manual for instructions on replacing the filter and reassembling the mower.

Inspect the safety release mechanism cable.

Your lawn mower’s reluctance to start may have nothing to do with the engine at all but rather with one of the mower’s safety features: the dead man’s control. This colorfully named safety bar must be held in place by the operator for the engine to start or run. When the bar is released, the engine stops. While this mechanism cuts down on the likelihood of horrific lawn mower accidents, it also can be the reason the mower won’t start.

The safety bar of a dead man’s control is attached to a metal cable that connects to the engine’s ignition coil, which is responsible for sending current to the spark plug. If your lawn mower’s engine won’t start, check to see if that cable is damaged or broken. If it is, you’ll need to replace it before the mower will start.

Fortunately, replacing a broken control cable is an easy job. You may, however, have to wait a few days to get the part. Jot down the serial number of your lawn mower, then head to the manufacturer’s website to order a new cable.

Check to see if the flywheel brake is fully engaged.

The flywheel helps to make the engine work smoothly through inertia. When it isn’t working properly, it will prevent the mower’s engine from working.

If it is fully engaged, it can make a mower’s pull cord hard to pull. Check the brake pad to see if it makes full contact with the flywheel and that there isn’t anything jamming the blade so the control lever can move freely.

If the flywheel brake’s key sheared, the mower may have run over something that got tangled in the blade. It is possible to replace a flywheel key, but it does require taking apart the mower.

Look out for signs that the mower needs professional repairs.

While repairing lawn mowers can be a DIY job, there are times when it can be best to ask a professional to help repair a lawn mower. If you’ve done all of the proper mower maintenance that is recommended by the manufacturer, and gone through all of the possible ways to fix the mower from the steps above, then it may be best to call a pro. Here are a few signs that indicate when a pro’s help is a good idea.

• You see black smoke. The engine will benefit from a technician’s evaluation, as it could be cracked or something else might be worn out.
• Excessive oil or gas usage. If you’ve changed the spark plugs, and done all of the other maintenance tasks, and the mower is consuming more than its usual amount of oil or gas, consult a professional for an evaluation.
• The lawn mower is making a knocking sound. When a lawn mower starts making a knocking sound, something could be bent or out of alignment. It may be tough to figure this out on your own, so a pro could help.
• A vibrating or shaking lawn mower can be a sign of a problem beyond a DIY fix. Usually something is loose or not aligning properly.

Honda Lawn Mower Carburetor Adjustment: How to Do It

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When your Honda lawn mower’s engine doesn’t idle, lacks power at high speed, or won’t start, it could be time to adjust the carburetor. If you have never done this before, you are probably wondering how difficult it will be, what tools you will need, and if you should just call an expert.

Adjustments to a Honda lawn mower’s carburetor should be made after it has been cleaned. If the carb is dirty, adjustments will be temporary. You will need some screwdrivers, a wrench, a carb cleaner, and an hour or two. Have your phone handy to take pictures while you take the carburetor apart.

Keep reading to find out how a carburetor works, what could be causing different problems, as well as preventative measures.

How Does a Carburetor Work?

Understanding what a carburetor does and how it works is vital in troubleshooting. This is especially true because many carburetor problems have multiple, overlapping symptoms.

The carburetor’s role is to provide the space where gas and air mix. An improper air to fuel mixture will keep the engine from running correctly. An incorrect gas and air mix cause most carburetor problems. Your job is to figure out what is causing the mix to be off.

• Float Chamber: The float chamber holds fuel, and as the amount of fluid increases, the float rises until it is pushed into its seat. When fuel leaves the chamber, the float falls. As more fuel enters, it rises again.
• Intake: Air rushes through the throat of a carburetor, and then a narrower passageway called a venturi. This causes the air to speed up, creating a vacuum that pulls fuel into the fuel nozzle.
• Fuel Jet: Once the proper gas/air mixture has been created, the fuel is pulled through the fuel jet. This creates the explosion that powers the engine.
• Throttle Valve: This valve controls the amount of gas that goes into the carburetor. An open valve increases the engine’s power, and a closed valve stops the engine.

Carburetor problems can occur at each of those points, and the way to fix most carburetor problems is to get inside and see which of these is causing the problem.

Why You Should Clean the Mower’s Carburetor

Although you might be tempted to play around with the throttle or make other adjustments, clean the carburetor. Otherwise, any corrections you make will be temporary, and you could wind up causing even more damage to the carb.

Also, get a parts cleaner, such as WD-40 Specialist Carb/Throttle Cleaner. It contains the solvents you need to clean out the gunk, and the spray will blast away dirt and deposits. For tools, you will need screwdrivers and a socket wrench.

Mower Engine Starting Problems

If your engine is not starting, you have difficulty starting it, or it stops after you get it started, then the following could be causing starting problems:

• The main jet, main nozzle, or main nozzle air path could be clogged.
• The float isn’t moving correctly.
• The throttle stop position is wrong.

Mower Speed Problems

If the engine speed does not increase, the speed is unstable, or the engine performs poorly at high speed, then an additional clog to check for is the pilot jet—either its air path or the jet itself are clogged.

Should speed problems happen at low speeds or the idle speed is unstable, then in all likelihood, the pilot jet or its air path is clogged. You will need to check for dirt and clean.

Mower Gasoline Problems

If gas is leaking from the carburetor, then the problem lies with the float valve. Either the float valve is worn out or coated with dirt, or the valve seal is worn or dirty.

Getting to the Mower’s Carburetor

Before you get started, we recommend you disconnect the spark plug cap. This is to prevent the mower from accidentally starting. Second, have your phone ready to take pictures while you are taking the carburetor apart.

Fix Without Taking the Carburetor Apart

You might get lucky and avoid having to take the carburetor apart. To do so, FOCUS on cleaning out the carburetor idle jet. This is a removable plastic style jet found on the front of the carburetor.

• First, spray the carb cleaner and remove the dirt and gunk.
• Look for a plastic screw with a Phillips head bolt. That’s the idle adjustment screw. Loosen and remove it.
• Now you will have access to a rubber plug with a hole. This is the idle/pilot jet.
• To remove the pilot jet, you need to pull it out gently. Use flathead screwdrivers to wedge it up.
• After you get it out, you should clean it with the carb cleaner. The small hole on the end often gets plugged. Honda makes Jet Cleaner sets, but a tiny pin will be a good substitute.
• After you have cleaned the pilot jet, push it back in carefully, and then replace the idle screw. Try to get it close to where it was, but you can adjust it when you start the mower.

Clean Out the Float Bowl

The float bowl is at the bottom of the carburetor. It is easy to take off, but before you do, turn off the fuel line. Then loosen the bolt on the bottom and take out the bowl.

There are two gaskets—one where the bowl connects to the housing, and another one on the bolt. Inspect both for cracks. Then clean out the bowl and replace the housing.

Copyright protected content owner: ReadyToDIY.com and was initially posted on 2020-08-27.

Taking the Mower’s Carburetor Apart

If the mower is still not running correctly, then the carburetor must be taken apart so that you can clean it. This is a much more complicated procedure and could take an hour or more.

• First, remove the air filter. If it is dirty, replace it. A dirty air filter can affect how well your mower runs better. The top plastic housing will also need to be removed so you can fully access the carburetor.
• Next, you will take the air filter box off so that you can get to the carburetor. In most models, it is held on by two bolts. As you loosen the bolts, hold onto the carburetor. The bolts run through the carburetor and mount it to the motor housing.
• Now that you have access to the carb, get ready to start taking pictures. Anything you unhook needs to be hooked back correctly. Keep an eye out for the tiny spring attached to the top.
• Once you have taken the carburetor off, it is time to disassemble. As you do so, check the gaskets—worn ones need to be replaced. Continue taking the carb apart and cleaning. Every hole needs to be clear of dirt.

Finally, the carburetor will have to be reassembled. Hopefully, you took lots of pictures so that you have them as guides.

Rather than taking a carb apart, some folks simply buy a new carburetor. Be sure to check compatibility with your Honda Mower.

Check out this 12-minute video that will take you through the steps of fixing a lawn mower carburetor:

To prevent future problems, make sure you are following Honda’s recommendations. Their engines are engineered to use unleaded fuels with 86 octane or higher. Ethanol fuels can be used as long as the fuel has no more than 10% ethanol (E10). A fuel with methanol should contain no more than 5% methanol.

Copyright article owner is ReadyToDIY.com for this article. This post was first published on 2020-08-27.

Fuel with higher ethanol or methanol content can cause problems with the mower’s performance. The engine’s warranty does not cover damage to the engine caused by fuel with more than 10% ethanol.

If possible, regular unleaded gasoline is ideal. Avoid E85 at all costs because Honda considers it an alternative fuel since it is 85% ethanol and only 15% gasoline.

Storage Suggestions to Prevent Carburetor Problems

These are some suggestions to prevent future carburetor problems. Gasoline can begin to deteriorate within three to four weeks, so use these if you only mow every couple of weeks:

• Fill up the tank. As fuel is exposed to heat or air, it oxidizes and can gum up the carburetor’s jets. Keep the tank full to minimize how much gas can enter the tank through the vent.
• Run the engine out of gas. No fuel = no oxidation. If the mower only has a little gas in the tank, run it dry and close the fuel valve.
• Storage container. Make sure you close the container tightly and store it in a cool place. Honda discourages metal fuel containers since they might rust, and tiny rust particles can clog the carburetor.
• Fuel Stabilizer. Fuel stabilizers should be added if gas is stored either in the container or the mower for three months or longer. If you plan to use the mower within a year, there is no need to drain the gas from the fuel tank or carburetor—as long as you add the stabilizer.

Final Thoughts

Carburetors are an essential and often overlooked part of a lawn mower. If your mower is not running well and you have checked the air filter and spark plug, you might have to work on the carburetor. Taking the carburetor apart and cleaning it is time-consuming but not difficult. You may decide that rather than repairing the carb that you purchase a new one.

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ReadyToDIY is the owner of this article. This post was published on 2020-08-27.