Cub Cadet Carburetor Problems

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The carburetor is an important component of your Cub Cadet lawn mower or tractor. It provides the correct air-fuel mixture for the engine combustion chamber.

However, the carburetor can develop a fault at any time. Some Cub Cadet carburetor problems include carburetor leakage, carburetor running too rich/thin, and flooded carburetor

In this article, I share 5 Cub Carburetor problems, and causes and proffer solutions to enable it to function efficiently. 

Cub Cadet Carburetor Problems, Causes, and Possible Solutions

Before I go into details, let’s look at some common Cub Cadet carburetor problems and their possible solutions:

Problems

Possible Solutions

1. Cub Cadet Carburetor Surges Continuously

  • Clear the clogs in the tiny hole. 
  • Replace the broken shaft.

2. Carburetor Adjustment Problems

  • Adjust the float according to the instructions in your service manual.
  • Replace bent choke or throttle plates 

3. Flooded Cub Cadet Carburetor

  • Rebuild the carburetor
  • Replace the bad gaskets or seals.

4. Carburetor is Running Too Rich/ Too Lean

  • Clean the carburetor.
  • Adjust the carburetor setting properly

5. Cub Cadet Carburetor Leaks

  • Clean, rebuild or replace the carburetor.
  • Change the missing carburetor bowl gasket.
  • Replace the defective float needle. 

1. Cub Cadet Carburetor Surges Continuously

A Cub Cadet garden tractor user complained that the carburetor surges continuously and won’t idle without dying. 

It could be that the hole in the throttle shaft is clogged or the governor shaft is broken. This will affect the performance of the lawn mower. 

Causes

  • The hole in the throttle shaft is clogged
  • Broken governor shaft

Fix

  • Check the throttle bore with the choke open and clear the clogs in the tiny hole. Ensure that you set the governor and the points properly.
  • Replace the broken shaft with a new one.

2. Carburetor Adjustment Problems

A Cub Cadet 127 owner had issues with the adjustment of the carburetor float. According to the owner, the motor operates smoothly but it puffs out smoke and smells like gasoline.

It is important to check the air filter to confirm if the gas is sitting in the throat of the carburetor. Another likely problem is bent choke or throttle plates

You can also check other components such as the head gasket, new plug, and fuel system if the problem persists.

Causes

  • The carburetor float is out of adjustment
  • Bent choke or throttle plates

Fix

  • Take off the air filter and check if the gasoline is sitting in the throat of your carburetor. If the vent is wet with gas, it indicates that your float may be a bit high. You can also lean the main jet a bit if the float is not too high. Adjust the float according to the instructions in your service manual.
  • Replace bent choke or throttle plates with new ones. 

3. Flooded Cub Cadet Carburetor

A Cub Cadet 1250 owner complained that the carburetor of the lawn tractor is flooding. This makes the lawn tractor difficult to start and can also sputter for a couple of minutes before it operates.

This can be a result of sticky trash or dirt in the carburetor. You also need to inspect the gaskets or seals for defects.

Causes

  • Sticky float or dirt in the carburetor
  • Bad gaskets/seals

Fix

  • Rebuild the carburetor
  • Replace the bad gaskets or seals.

4. Carburetor Is Running Too Rich / Too Lean

If your Cub Cadet mowing machine runs too rich, it indicates that the engine is receiving too much fuel. In this case, black smoke may begin to come out of the muffler. 

If the carburetor of your Cub Cadet lawn mower runs too lean, it means that the engine is receiving too much air. This can hinder the performance of the mower engine.

Causes

  • Carburetor is dirty
  • Incorrect carburetor settings

Fix

  • Clean the carburetor.
  • Adjust the carburetor setting properly or contact an expert to help you to fix it

5. Cub Cadet Carburetor Leaks

If the carburetor of the engine leaks gas, it might be a result of a float that is stuck open. 

Another likely problem may be that the carburetor bowl gasket is missing or the float needle is damaged. In this case, it can hinder the performance of your Cub Cadet lawn mower/tractor.

Causes

  • Float is stuck open
  • Missing carburetor gasket
  • Damaged float needle

Fix

  • Detach your carburetor assembly from the engine and ensure that it is properly cleaned. Rebuild or replace it if the cleaning is not effective.
  • Change the missing carburetor bowl gasket with a new one.
  • Replace the defective float needle. 

Symptoms of a Bad Carburetor on Your Cub Cadet Lawn Mower

Here are some symptoms of a bad carburetor on your Cub Cadet lawn mower:

  • The mower  won’t start
  • The engine will run rough or sputter
  • Cub Cadet mowing machine backfires because it runs lean.
  • Lawn mower consumes too much fuel
  • Engine surges
  • Black smoke comes out of the muffler from running too rich.
  • The mowing machine  starts and then dies

How to Clean the Carburetor on a Cub Cadet Riding Lawn Mower

Here are the steps for cleaning the carburetor of your Cub Cadet riding lawn mower:

Step One: Spray Carb Cleaner into the Air Intake

Detach your air filter from the air filter housing and spray your carb cleaner into your air intake.

Turn on the mower engine to check if it will fire up and operate well. If it fails to fire up and shuts down in the process, it means that you need to disassemble and clean the carburetor.

Step Two: Gather The Tools Required For The Job

You need to gather these tools to clean the carburetor of your mowing machine:

  • Thick wire
  • Screwdriver
  • Needle nose pliers
  • Pliers
  • Carburetor cleaner
  • Socket/ratchet set

Step Three: Snap Photos for Its Reassembly

You need to snap photos while disassembling the carburetor. Some components may fall apart in the process. 

In this case, it may be a hard task to remember their exact positions after you have disassembled the carburetor.

Take several photos so that you can refer to them when you have started reassembling the carburetor.

Step Four: Shut off the Fuel Supply

To stop the gas supply, use fuel hose pinch-off pliers to crimp the fuel line or put off the fuel shut-off valve.  Furthermore, detach the fuel line away from your Cub Cadet carburetor. 

Step Five: Take Off the Throttle Cable and Choke Cable

It is also advisable to detach the throttle and choke cable if you have them on your model.

Step Six: Take Off the Mower’s Filter Housing

Detach the nuts and screws that hold the Cub Cadet carburetor to the filter housing.

Step Seven: Remove Your Springs

Slowly detach the springs. Remove them gently so that you will not stretch them. To detach these springs, twist the carburetor a bit.

Make sure that you do cause damage to the gasket. This gasket is between the engine block and the carburetor.

Step Eight: Take Off the Float Bowl

You can find the float bowl beneath your engine carburetor. This float bowl is secured by a screw.

For you to wipe the dirt before taking off the bowl, ensure that you clean the outer part of your carburetor.

After that, take off the screw from beneath the bowl. Use your rag to collect the gas that is remaining in the float bowl.

When detaching the bowl, make sure that you do not cause damage to the O-ring that is located between the carburetor and the bowl. 

Do not use a carb cleaner on your carburetor’s o-ring. Using a carb cleaner on the o-ring may cause it to stretch.

Step Nine: Examine Your Stem for Blocked Holes

If the stem is clogged, it will stop your carburetor from getting gas to the jet. Use a flashlight to find the holes and disconnect them with a thick wire.

Step Ten: Check Your Cub Cadet Carburetor for White Crusty Buildup

A white buildup is caused by fuel additives and ethanol. Use a carb cleaner to wipe off the white crusty buildup. 

Although, it may not be possible to clean the entire crusty buildup out of your carburetor.

Step Eleven: Reassemble the Cub Cadet Carburetor

Reassemble the carburetor in the reverse order that you disassembled it.

Check the pictures that you snapped earlier to be sure that the small components are in their proper positions.

Reinstall the carburetor’s components, including the filter housing, springs, fuel line, choke, and throttle cable.

Step Twelve: Fill Your Gas Tank with Fresh Gasoline with Gas Additive

Start the fuel flow. Use fresh gas that is mixed with a gas additive in the fuel tank. Allow the gas to fill the bowl of the carburetor and turn on your lawn mower engine.

Frequently Asked Questions 

How do I know if my carburetor is clogged?

A: If your carburetor is clogged, you may notice signs such as the engine not starting, the engine running lean/rich, the engine running rough, or an increase in fuel consumption.

Will a seafoam clean a lawn mower carb?

A: Yes, a seafoam can clean and maintain carburetors.

Conclusion

If you notice that your Cub Cadet carburetor is giving you problems, the first thing to do is to figure out what is causing it. 

Some Cub Cadet carburetor problems include surging problems, carburetor leaks, and adjustment problems.

Follow the practical fixes to solve the problem with your Cub Cadet carburetor. 

If your carburetor does not work well after implementing the troubleshooting tips shared here, it is advisable to contact a lawn mower expert.