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Lawnmower loses power when cutting, what to do

You are mowing your lawn, you are halfway, and you notice that your mower loses power or even dies. This is frustrating, but we can help with some pretty easy ways to fix this issue. Without any doubt, it is essential to find out what is the leading cause that your Mower loses power during operation. Once the cause is known, it helps you determine the solution. In this blog post, we cover each facet concerning the common reasons why lawnmowers lose power, and we will tell you how to fix them.

Your lawn and garden machine needs three things to power the combustion process:

  • Air
  • Fuel
  • A spark to ignite the air-fuel mixture

A fallacious quantity of air or fuel causes the engine to function intermittently or not at all, as will a defected spark plug and thus ultimately loses power.

Lawnmower loses power when cutting, what to do:

  1. Change the air filter if it’s clogged or dirty.
  2. Replace fouled or dirty spark plug.
  3. Unclog or replace the gas cap if the air vent is blocked due to clippings and debris buildup.
  4. Replace dirty or clogged fuel filter.
  5. Replace old gas with fresh gas (properly dispose of old gas).
  6. Check oil level and add if low.
  7. Adjust cutting height of Mower before cutting tall grass.
  8. Dull, bent, or lose the mower blade must be sharpened or replaced.

The above steps (listed in order of plausibility) show many days to day problems and reasons regarding power loss. A particular course of action is then required to decide which is applicable.

Lawnmower loses power when cutting, check this:

1. Dirty or Clogged Air Filter

The air filter purifies the air before it is sucked into the carburetor, and when it performs its operation accurately, it may get obstructed with debris separated from the air. A clogged air filter may not permit a particular amount of air into the carburetor, minimizing the engine’s power. 

In lawnmowers, sward and sludge can clog up the air filter or congest the cooling fins. This stops up air from coming in, reducing the capabilities of the air-cooled engines. And eventually causes power loss by forcing the engines to slow down and overheat. Clean the dirt and debris from the cooling fins to recover the necessary power.

2. Stale Fuel

How long has it been since you filled your mower gas tank? Most often, minor fuel problems caused by deadly gas force a mower to stop operating when chopping grass. Grimy fuel is the basis for your engine to cease. Gas can go moldy in mere every 30 days, essentially mixed fuel (fuel + ethanol). After these 30 days, the gas standard will be found descending acutely as the components start segregating. Ethanol has a property to attract moisture over time that results in dilution of the gas. Other alternatives include adding a fuel stabilizer to your tank or utilizing a canned fuel that does not contain ethanol.

Suppose this low-grade fuel is provided to your lawnmower. In that case, your fuel system can eventually get into a bad condition, as bad fuel is prone to leave behind adhesive accumulations that obstruct the fuel flow. Moreover, to increase your problem, by any chance, if there is any gas left in the lawnmower during storage, it will stale and dry out.

3. Immoderate Engine Load

Occasionally you may be demanding way too much from your engine, which causes your engine to slow down. You may be exhorting your trimmer to take on an abrupt hillock with excessive weight. Or maybe you’re taxing to move your Mower through thick or long grass. Regardless of the reason, you’ll want to lessen the load to make your Mower operate properly.

4. Dirty or Clogged Fuel Filter

As the name suggests, a fuel filter removes dirt and debris from your engine’s fuel system before it enters the carburetor. Similar to an air filter, when the fuel filter performs its function, it will automatically become less productive and may get blocked, limiting fuel flow to the mowers’ engine.

Another reason may be dust and water in the fuel system. This will create a pressure increase in the carburetor, power loss, inefficient combustion, and sputtering. We can solve the issue by draining the fuel system or replacing the stale fuel with new fuel.

5. Long Grass

If we are trying to cut too tall grass, then it may be why our lawnmower loses power due to excessive loading.

6. Unacceptable Oil Level

Power loss may also occur due to varying levels of oil. Irregularity and damage occur due to both high and low crankcase oil level.

  • High oil level: A high oil level can result in instigating air into the lubrication system and decreasing the oil’s capacity to grease the setup, leading metal to burnish and due to excess friction causing power loss in the engine. Moreover, it can cause the oil to get frothy.
  • Shallow oil level: A shallow oil level can also diminish your system’s capacity to provide enough lubrication, rising friction, and setting more load on the mower engine. Moreover, the deficient oil level can also be why moving parts to seize up, be it temporary power loss or permanent seize up. 

7. Dirt and debris in Blades

As your lawnmower goes upward, various things like mud, dirt, litter, grass, corrosion, or any other buildup can cause power loss. All these things coat your blades and slow them down. Thus the motor needs to work harder to turn them. You can solve your problem by removing and cleaning the things that are blocking blades beneath the engine blower housing or replace the lawnmower’s blade. Always ensure that your Mower is turned off before trying to access any of its parts.

8. Defective Spark Plug

An unaligned or corroded spark plug will cause erratic ignition as it will not create the spark required to ignite fuel vapors during the upward movement of the engine’s piston. The electrodes of spark plugs, with passing time and usage, become covered with different substances like fuel, dirt, debris, carbon, and oil, so every season, we should replace the plugs after inspecting them properly to circumvent power loss.

We should check spark plugs in case of any performance problem on a priority basis as they can be removed, replaced, or cleaned very quickly.

9. Blocked Muffler

The muffler is the mower part which expels the burned gas and other vapors out. Muffler blocked with dirt, debris, and other fluids can cause severe problems as it does not allow the burned gases from exiting your Mower. If the colored smoke is coming out from your Mower, then there are high chances that the muffler is clogged and maintenance is needed.

10. Carburetor Issues

If you’ve ruled out other potential issues, the problem might be your carburetor. The carburetor mixes the gas with air to form the ignitable fuel used to power the engine. If the carburetor is not clean, the fuel vapors required to provide the Mower the extra power for going uphill will not be available. The carburetors of lawnmowers usually have three screws that can be adjusted. These adjustable screws determine the rate at which fuel will be consumed for different speeds of the engine. However, adjusting these carburetor screws can be very problematic, as even the slightest adjustments can cause drastic impacts, so it would be better to allow a professional to adjust the screws of the carburetor.

However, if a carburetor requires adjusting too often and too much, it depicts that the inlet bores are very dirty and do not allow adequate fuel in. Impurities in the fuel, from stale gas, can cling to the bore, the screen, and other delicate parts inside the carburetor. And when this occurs, the carburetor will smother, causing the engine to run poorly or shut it down. According to the owners’ manual for your Mower, you’ll require to detach and immaculate the carburetor. The problem will be solved by cleaning the carburetor and replacing damaged seals or gaskets.  A professional should perform all carburetors’ cleaning; however, you must ensure that he installs a carb kit or not before reinstalling the carburetor.

If still, Mower’s operation problems persist while going uphill, you should have a professional check of the choke switch; either replace or repair it if it is a problem causer.

Frequently Asked Questions:

1. What to do when a lawnmower loses power when blades are engaged?

If your lawnmower loses power when blades are engaged, you generally need to check the Mower’s belts, pulleys, and switches. When the belts are not properly routed, they will raise this issue, so you need to check if they are adequately routed or not and remove all the spindle covers to end this problematic situation. Belts drive pulleys, which in turn move spindles. If the pulleys cannot turn freely, they would cause the engine to die as soon as the blades are engaged. Replace the pulley if it is damaged or sticky. The engine would die when blades are engaged due to damaged safety switches, so check if they are adequately plugged. Then, check if it is damaged or not, replace it in case of worn off switch, and use a multimeter to check whether it works.

2. Why my lawnmower is running slow and rough?

The first reason for a lawnmower running slow can be clogging in its different parts like fuel line, air filter, carburetor, gas cap, and last but not least, needle and seat. Clean these parts, and for cleaning, first disconnect and then ground the spark plug wire. If gas caps or needles and seats are clogged, you should replace them rather than cleaning. Fuel mixture can be one of the reasons for the slow-motion of a lawnmower. In this case, you should try fuel from different providers because maybe the fuel you are already using is not suitable for your Mower. Air trapped in transmission, bad battery, and worn motion drive belt can be the reasons for slowing down the lawnmower.

3. Why is my riding mower not cutting?

Severely worn or dull blades will tear the grass instead of cutting it. This can leave gaps in the cut and increase clumping of the clippings. Missing material or bent blades can cause an uneven cut and vibration when the deck is engaged. Inspect your blades before every cut.

Final remarks:

Lawnmowers are probably a gardener’s equipment that offers the greatest return on investment. So, it is aggravating when a lawnmower loses power in the middle; here, your patience is tested. Even those who aren’t experienced working with machines, engines, fixing clogged or dirty engine parts are relatively easy and can save you money. This guide will come in handy and facilitate you to troubleshoot the power issues. When a lawnmower malfunctions, it does not mean it is broken. Maybe it could only be that its engine components just need a little bit of “love” and “care.” So, consider following all these steps for a long-lasting and trustworthy mowing experience.