How to Rebuild a Line Trimmer Carburetor


chainsaw carb rebuild kit 3604379513

The line trimmer carburetor controls the air/fuel mixture that ignites in the cylinder to drive the engine. If the gas tank has plenty of fresh gas but the engine won’t start, check the carburetor by taking off the air filter, pouring about a teaspoon of fuel into the carburetor and pulling the starter rope. If the engine starts then dies, the carburetor is probably the problem. You can rebuild the carburetor with the manufacturer-approved rebuild kit, following the steps in this line trimmer repair guide.

Use this basic procedure to rebuild the carburetor on Craftsman, MTD, Toro, Weed Eater, Troybilt, Snapper, Cub Cadet and Poulan line trimmers.

Another option is to install a new carburetor, following the steps in How to Replace a Line Trimmer Carburetor.

Repair difficulty:
Time required:

Less than 30 min.

Parts Required

  • Line trimmer carburetor rebuild kit
  • Primer bulb (if needed)
  • Mounting gasket (if needed)

For manuals, repair guides, and specific part recommendations, enter your model number.

Tools Required

  • Needle-nose pliers
  • Phillips screwdriver
  • Allen wrench
  • Approved fuel container
  • Rags
  • Work gloves
  • Safety glasses

Before you begin

Let the engine cool. Wear work gloves to protect your hands.


 Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

Step 1: Disconnect the spark plug wire

Disconnect the wire from the spark plug.

Step 2: Drain the fuel tank

In a well-ventilated area, remove the fuel cap and the drain the tank into an approved storage container. 

Step 3: Disconnect the fuel lines

Document the configuration of the fuel lines attached to the carburetor (taking a digital picture of the lines is an easy way to keep track of  their location).

Pull the fuel lines off of the carburetor, using needle-nose pliers if necessary.

 Tip: For accurate reassembly, take digital photos of the throttle linkage on the carburetor and the gas line connections.

Step 4: Remove the air filter

Remove the cover from the air filter housing and then remove the air filter.

Step 5: Remove the carburetor

Use an Allen wrench to remove the 2 mounting screws that secure the carburetor to the engine.

Pull the air filter housing off of the carburetor. Remove the carburetor from the side of the engine. The throttle cable is still attached to the carburetor.

Take a digital photograph of how the throttle cable control cable connects to the carburetor or make a diagram. Disconnect the throttle cable and remove the carburetor.

 Tip: Check the gasket on the side of the engine and replace it if it's damaged.

Step 6: Remove the bottom cover and diaphragm

Place the carburetor on a clean work surface.

Use a Phillips screwdriver to remove the screws from the bottom cover of the carburetor.

Remove the cover and then pull off the diaphragm and gasket. 

 Tip: Line up the components on your work surface so that you can replace the parts in order.

Step 7: Remove the top cover and primer bulb

Remove the top cover with the primer bulb from the carburetor. Replace the primer bulb if it is stiff or damaged.

Step 8: Remove the screw securing the needle and fuel lever

On the bottom of the carburetor, note how the lever, spring, and hinge pin fit together. Remove the screw and pull those components out of the carburetor.

Step 9: Clean the carburetor and let dry

Clean all ports and jets in the body of the carburetor with aerosol carburetor cleaner and compressed air.

Allow the carburetor dry for at least 10 minutes. Some carburetor cleaners can damage the diaphragms if the carburetor is reassembled when it is still wet.

Step 10: Reassemble the carburetor with new parts

Install the needle and lever on the bottom of the carburetor. Secure those components with the screw. Then install the gasket, diaphragm and cover. Be sure to install them in the correct order. Install the top cover and primer bulb. Be sure that you install the components in the same order and manner in which they were removed.

 Tip: The kit might have parts not used on your carburetor; use only the parts that match your original carburetor components. Don't reuse old components.

Step 11: Reconnect the fuel lines

Referring to your digital image or other documentaiton, connect the fuel lines to the new carburetor.

Step 12: Reinstall the air filter and spark plug

Clean the air filter if necessary before installing it. Position the filter in place and close the cover on the filter housing.

Connect the spark plug wire on the spark plug.

Step 13: Test

Fill the gas tank with the fuel mix and check that the line trimmer works.