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This is Why Your Honda Lawn Mower Loses Power (Solved!)

You’re pushing your Honda mower along when you notice it isn’t giving you the power it once did. It begins to bog down and run sluggish and the engine isn’t performing at its best. There are many items that can affect the way your engine runs.

A Honda lawn mower may lose power when it is not able to get the fuel or air the engine requires. This could be due to a plugged air filter, bad fuel, clogged fuel filter, clogged fuel lines or dirty carburetor. The Honda mower may also lose power due to a low engine oil level, clogged mower deck, slow engine speed or fast ground speed.

Honda lawn mower loses power

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, knowledge or are not in the condition to perform the repair safely.

Reasons Your Honda Lawn Mower Loses Power

Plugged Honda Mower Air Filter

Check your air filter when your experience a loss of power. A plugged air filter restricts the amount of air the engine receives. When the engine isn’t able to get the air it requires, your Honda mower may run sluggish and possibly quit.

Clean and replace it as necessary following these steps for a paper air filter element:

  • Remove the air filter from the air filter housing.
  • Wipe out any remaining dirt in the housing with a dry cloth. Be careful not to allow dirt to fall into the air intake.
  • Tap your air filter against a solid surface to knock as much dirt loose as possible.
  • Hold your filter up to a light source.
  • Reuse your filter if you can see light through the paper element.
  • Replace with a new filter if you can’t see light through the paper element.

Bad or Old Fuel in Your Honda Lawn Mower

Because gasoline can begin to break down and become unstable as soon as 30 days after purchase, it is important to either consume your fuel quickly or add a fuel additive to your gasoline to stabilize your fuel.

Ethanol contained in gasoline today attracts moisture to the fuel system. This ethanol and moisture can gum up and begin degrading the fuel system. Not only can this cause clogging and fuel restrictions, it can be harmful to your engine.

Here are a few tips to take when purchasing gas for your Honda lawn mower:

  • Buy fuel from a busy gas station.
  • Use an unleaded gasoline with a minimum octane rating of 87 and maximum ethanol content of 10 percent. The lower the ethanol content, the better.
  • Add a fuel additive to stabilize your gasoline and reduce moisture.
  • Store any remaining fuel in a cool dry area away from the outdoor elements.

Remove old fuel from your Honda using a fuel siphon. Fill with fresh gasoline. To learn more about gasoline and fuel additives read these articles: “Why Use Sea Foam Additive in a Lawn Mower” and “This is the Gas Your Honda Lawn Mower Uses”.

Clogged Honda Mower Fuel Filter or Fuel Lines

When fuel can’t get to your engine because of a clogged fuel filter or fuel line, your Honda mower will experience a loss of power. Dirt and gummy deposits from running bad fuel can collect in your fuel filter and fuel lines. Replace a clogged fuel filter installing the new filter with the arrow on the housing pointing in the direction of the fuel flow. The arrow should be pointing toward the carburetor.

Check for clogged fuel lines by stopping and starting flow while checking sections of your fuel line. You can use the fuel shut-off valve or crimp your fuel line to start and stop flow. When you identify a clog in a section of fuel hose, remove the hose from your Honda mower.

Spray carburetor cleaner in your fuel line to loosen up the blockage. Follow this by blowing compressed air into the line to remove the clog. Repeat these steps if necessary. If you are unable to remove the blockage, replace it with a new fuel line.

Dirty Carburetor on Your Honda Lawn Mower

A carburetor’s purpose is to regulate the fuel and air mix required to form a combustion in the engine. When the carburetor becomes dirty from running old fuel through your Honda, components in your carburetor can become clogged preventing a sufficient supply of fuel from getting to the engine.

Disassemble the carburetor and clean it to remove fuel restrictions caused by gumming and hard crusty deposits. Check your components to make sure they are in good working condition.

If you are a little mechanical, follow my instructions in this guide to clean the carburetor. You may also choose to have a small engine repair shop perform this for you. If the carburetor still fails to correctly supply fuel, you will have to replace the carburetor assembly.

Bad Spark Plug on Your Honda Lawn Mower

A fouled spark plug can cause intermittent spark that can cause a loss of power. Inspect your spark plug for signs of carbon, dirt and oil buildup on the tip. If you find a dirty or damaged spark plug, I recommend replacing it with a new one to ensure you’re running a good plug in the mower.

Alternatively, if it’s only dirty and not very dark in color, you can attempt to clean it with a wire brush and reuse it.

Engine Power is Too Slow on Your Honda Lawn Mower

Your Honda mower deck requires full engine power to run. The throttle must be set to the “fast” position when your mower deck is engaged. Check your throttle lever to make sure it is in the correct position.

Low Engine Oil in Your Honda Lawn Mower

When the engine oil in your Honda mower is at a low level, there isn’t enough lubrication to keep the moving parts in your engine moving freely. Increased friction can build heat in the engine causing a power loss. If a low engine oil level isn’t caught quickly enough, it can result in a significant engine repair bill.

Because of the damage a low engine oil level can cause to your Honda mower, it is good practice to check the engine oil level before each mowing. Doing so may catch engine problems at an early stage before it develops into a larger issue.

To fix, bring your engine oil level to the correct level using the lines on your dipstick for reference. If you caught your problem soon enough, you may be able to fix it by adding engine oil and identifying the reason why your engine level is low. If you didn’t catch it early, you could have serious engine damage that should be diagnosed by an experienced small engine mechanic.

Too Much Engine Oil in Your Honda Lawn Mower

Overfilling the crankcase with engine oil will cause your engine to smoke. Increased pressure builds as a result of too much engine oil and oil can be pushed into the cylinder through the valve train. When this happens, a bluish white smoke is emitted when oil burns in the cylinder.

This thick cloud of smoke can plug your air filter causing running issues because your engine isn’t able to get the clean air it needs. Check your air filter and your spark plug, clean or replace if needed.

Continuing to run your Honda mower with too much oil can cause seal damage, the engine to hydrolock, and a bent piston rod. Correct and engine with too much oil by removing a little oil. You can do this by using an oil evacuator, the drain plug or even a turkey baster.

Ground Speed is Too Fast on Your Honda Lawn Mower

Mowing your lawn at too fast a speed can put extra load on your mower and cause it to lose power. Your engine must work harder in thick grass covered lawns over thinly covered lawns. Adjust your mowing speed according to your mowing conditions.

Cutting Wet or Tall Grass

Avoid cutting wet or tall grass as this will strain the engine causing a poor cut and extra load on the engine. Mowing grass when it is dry will reduce the amount of grass clippings collecting under the deck.

To mow taller grass, adjust the cutting height to its highest height and make your first cut. Follow it by lowering your mower deck and making a second cut. If your grass is extremely tall, I recommend using a walk-behind brush cutter to cut down the grass and make it manageable going forward.

Check out your local rental center for options to rent a brush cutter. You can read more about cutting tall grass in this article.

Honda Mower Deck is Clogged

Keep your mower deck clean and free of grass clippings and debris so your blades can spin freely. The engine will lose power when it is required to work hard to turn blades through a deck packed with debris.

Scrape your mower deck regularly to remove debris collecting under the deck. The area under the deck uses the air movement created by the blades to form a suction to stand the grass tall for a good cut. A clogged mower deck not only causes a loss of power, it also creates a bad cut because it restricts air movement under the deck.

Dull Mower Blades on Your Honda Lawn Mower

A dull mower blade can further magnify the power loss your experience when, not only does the engine need to turn blades into a deck packed full of debris, but it now how to turn dull blades through this debris.

Remove your mower blades and sharpen the blades using this guide for your Honda mower blades. Mower blades need to be sharpened at least after every 25 hours of use. They may need to be sharpened more frequently when using your mower in sandy or gravel conditions.

In Summary

Performing routine maintenance on your Honda lawn mower and checking your engine oil before you mow can prevent engine problems that cause a loss of power. If none of the items above solve your power loss problem, take you mower to the local small engine mechanic to be looked at. There are internal engine problems that are hard for the homeowner to diagnose without the proper engine tools to accurately perform tests on the engine.

Is Your Honda Lawn Mower Smoking?

You can experience a loss of power from items that cause your lawn mower to begin smoking. If your Honda mower is smoking, check out this article for more details.