How to Clean a String Trimmer Carburetor

Remove the air filter cover and air filter. Disconnect the spark plug wire.

Drain or empty the fuel tank. Remove the fuel lines connected to the carburetor — note which line goes where (supply vs. return).

Remove the carburetor mounting screws and disconnect the throttle cable. Carefully remove the carburetor.

Disassemble the carburetor. Most trimmer carbs have a primer side and a diaphragm/metering side. Remove the screws on each side and carefully separate the layers.

Note the order of gaskets, diaphragms, and screens. Take photos of each layer as you remove it.

Spray all passages and openings with carburetor cleaner. Pay special attention to the fuel inlet screen and metering needle valve.

Use a small wire to clear any clogged passages. Blow through with compressed air.

Install new gaskets and diaphragms from a rebuild kit. Old diaphragms get stiff and don't flex properly. This is the most common fix for trimmer carb issues.

Reassemble in reverse order. Reconnect fuel lines (supply line connects to the primer bulb inlet side).

Reinstall the carburetor, reconnect throttle cable and fuel lines. Prime the bulb 5-8 times and try starting.