Craftsman Riding Mower Loses Power When Blades Are Engaged

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If your Craftsman riding mower loses power when blades are engaged, it might be due to a defective spark plug, dirty carburetor, worn-out blade spindle bearings, or worn or loose belt.

In this article, I share 10 possible reasons why your Craftsman riding mower loses power when the blades are engaged and practical fixes to solve the issue. 

Reasons Why Your Craftsman Riding Mower Loses Power When Blades Are Engaged

Some of the reasons why your Craftsman riding mower may lose power when blades are engaged may include:

  • Dull blade
  • Blocked muffler
  • Worn out blade spindle bearings
  • Clogged fuel filter/fuel lines
  • Dirty carburetor
  • Dirty underside
  • Defective spark plug

Tools You Need for This Job

  • Wrench set 
  • Nut driver set, 
  • Pliers, 
  • Work gloves 
  • Shop rag 
  • Hose pinch-off pliers.

Craftsman Riding Mower Loses Power When Blades Are Engaged: Possible Causes and Fixes

1.  Dull Blade

When the blade is dull, it has to work harder to mow through the grass which can cause the mower engine to lose power when blades are engaged. 

This will further affect the functionality and performance of your Craftsman lawn mower.

Diagnosis

  • Inspect the blades to see if they are dull.  

Fix

2. Blocked Muffler

The muffler of your Craftsman riding mower is responsible for reducing exhaust noise and also preventing exhaust sparks from igniting dry grass.

When it gets clogged by dirt, fluid, grass and other debris, it can cause your Cub Cadet mowing machine to lose power.

Diagnosis

  • Inspect your muffler for dirt, grass, fluid and other debris
  • If you detect a colored smoke that comes out from your Craftsman riding mower, it might indicate that the muffler is clogged.

Fix

  • Ensure that you change the blocked muffler. 

3. Worn Out Blade Spindle Bearings

This is one of the reasons why your Craftsman riding mower may lose power when the blades are engaged. 

The function of the bearings is to allow your mower blades to spin freely on their axis. Worn-out bearings can cause friction and result to power loss. Learn about the best grits for sharpening lawn mower blades.

Diagnosis

  • Check if the blades are spinning freely on their axis. If not, it indicates that the bearings in your blade spindles are worn out.

Fix

  • You need to change the worn-out blade spindle bearings. 

4. Clogged Fuel Filter/Fuel Lines on the Craftsman Riding Mower

Dirt and substances left behind by running old gas can cause the fuel filter and fuel lines to become blocked. This can cause fuel restriction and make the mower lose power.

Diagnosis

  • Check the fuel filter for clogs. If you notice that enough gas isn’t passing through the fuel filter or it is not enough to run at full throttle, it indicates that the fuel filter needs a replacement
  • Inspect for clogs in the fuel lines by starting and stopping the fuel flow, using the fuel shut-off valve situated on the bottom of the fuel tank.
  • Take off the furthest end of the fuel line (just one section) and place it in the container.
  • You can also check other sections of the fuel line for clogs. If the line is cracked or dry, you may need to replace it with a new fuel line.

Fix

  • Replace the fuel filter if it is in bad condition.
  • To fix clogged fuel lines, remove the section of the line and spray a carburetor cleaner into the line to help loosen the clogs.
  • Blow compressed air through the line to eliminate obstructions.
  • Replace the fuel line if it is dry or cracked.

5. Dirty Carburetor

A dirty carburetor can be one of the reasons why your Craftsman riding mower may lose power when the blades are engaged.

The carburetor is likely to become dirty and may form crusted and gummy spots where deposits from bad gas have formed.

In this case, your carburetor may not be able to regulate the amount of gas and air that your engine requires to run, causing the mower to lose power. 

Diagnosis

  • Check the carburetor for dirt and other substances left behind by the old gas.

Fix

  • Clean the carburetor or replace it if it is in bad condition.

How To Replace A Carburetor on a Craftsman Riding Lawn Mower

Here are some steps on how to replace a carburetor on your Craftsman riding lawn mower:

Step One: Gather The Required Tools

The first step to take is to gather the required tools. You need to gather tools such as a wrench set, nut driver set, pliers, work gloves, shop rag and hose pinch-off pliers.

Step Two: Disconnect Your Battery

Ensure that you park your riding lawn mower on level ground and in a well-ventilated place. Make sure that you set the mower’s parking brake

Turn off the ignition switch, take off the key and allow your engine to cool down.  It is advisable to wear a pair of work gloves to shield your hands.

Lift the mower’s seat and take off the bolt that connects the negative wire to the battery Tuck the wire away from your battery to prevent it from touching the battery post.

Step Three: Take Off the Engine Blower Housing of Your Craftsman Riding Mower

Ensure that you lift the hood of the mower. Take off the air duct mounting screws and remove your air duct. 

Remove your air filter cover by turning each air filter cover retaining knob counterclockwise.

Step Four: Disconnect The Fuel Line

Remove the lower dash by taking off the lower dash fastener. Use hose pinch-off pliers to clamp off the fuel line.

Release the clamp that holds the fuel line to the carburetor and remove the fuel line from your carburetor. To catch drips, you need to use a shop rag. Make sure that you clean up any spilled gas.

Step Five: Take Off Your Carburetor

If you want to remove your carburetor, it is important to detach the air intake mounting nuts. Also, remove the breather tube and take off the air intake.

Detach the cable from the fuel solenoid. Take a picture of the carburetor linkage connections to know their right location when it’s time to reassemble them.

Ensure that you take off your carburetor mounting studs and disconnect your throttle spring and throttle rod. Furthermore, disconnect the choke rod and remove your carburetor.

Detach the engine’s intake gasket and clean the gasket mounting surface.

Step Six: Install The New Carburetor

Place the replacement carburetor close to the engine and reattach your choke rod. Connect the throttle rod and spring and install the new intake gasket on the engine.

Mount the carburetor on the engine with the mounting studs and make sure that the studs are firmly tightened.

Connect your fuel solenoid cable and reconnect the air intake and carburetor after attaching the breather tube to the air intake. Install your air intake mounting nuts.

Step Seven: Attach the Fuel Line

You need to attach the fuel line to your carburetor. Take off your hose pinch-off pliers from the fuel line.

Step Eight: Reinstall the Engine Blower Housing

Reinstall the lower dash and secure it with a fastener. Put the blower housing on the engine and align the air diverter in the housing.

You can now install other parts such as the blower housing mounting bolts, air filter housing screw and air filter and air filter cover accordingly.

Position the air filter cover on the engine and turn each retaining knob clockwise on the cover.

In addition, install the air duct and attach it with the mounting screw. After that, you can now lower the hood of your Craftsman riding mower.

Step Nine: Reconnect Your Mower Battery

Reconnect the negative wire to the negative battery terminal and lower the seat of your mowing machine. 

6. Dirty Underside

A dirty underside might be one of the reasons why your Craftsman riding mower may lose power when the blades are engaged.

Whenever the blade is engaged, the underside rotates on a crankshaft to mow the grass. The mower engine can shut off if there is an interference in this rotation.

Diagnosis

  • Inspect the connection of the crankshaft to see if it rotates freely. If the crankshaft’s connection does not rotate freely, it indicates that the mower’s underside is dirty.

Fix

  • Clean the blade so that it will be free of debris, dirt and grass. 

7. Loose or Worn Mower Belt

When mower belts are not properly routed, they will cause issues when the blades are engaged. 

In addition, a loose belt can also slip off the pulleys, causing the mower to lose power.

Diagnosis

  • Examine the belt for wear, cracks, breaks or slippage. 

Fix

  • Replace the belt if it is in a bad condition.

8. Bad Pulleys

The mower belt drives the pulleys, which in turn moves spindles. 

If the pulleys cannot turn freely, they would cause the engine to lose power. This will affect the operation of your Craftsman riding mower.

Diagnosis

  • Check pulleys if they are moving freely. If not, it indicates that the pulleys are bad.

Fix

  • Replace the pulley if it is sticky or damaged.

9. Defective Spark Plug

The function of the spark plug is to ignite the air and fuel mixture. If the spark plug is bad, it can cause your mower to lose power when the blades are engaged.

Diagnosis

  • Check the spark plug for signs of oil buildup, carbon and dirt on the tip.

Fix

  • If it is dirty, you can use a wire brush to clean it. It is best to replace it if the spark plug is bad.

10. Clogged Air Filter

The engine Craftsman riding mower requires air to run. If air is restricted through the air filter, it can cause the mower to lose power. 

This will affect the functionality and performance of the mower.

Diagnosis

  • Remove the air filter from the air filter housing and check for dirt on it.

Fix

  • Clean the air filter or replace it if it is in a bad condition. 

Conclusion

It is important to note that this is one of the most common Craftsman mower problems. Some of the reasons why your Craftsman riding mower may lose power when blades are engaged include a worn belt, defective spark plug, dirty underside, clogged air filter and dirty carburetor.

Follow the practical fixes to solve the problem. If your Craftsman riding mower does not work well after trying these troubleshooting tips, it is best to seek the help of a professional to help you to fix it.