5 Signs Your Lawn Mower Needs a Carburetor Cleaning

The carburetor is the heart of your small engine — it mixes fuel and air in the right ratio to keep your mower running. When it gets dirty or clogged, you'll notice problems quickly. Here are five signs it's time for a carburetor cleaning.

1. Hard Starting — If your mower takes multiple pulls to start, or won't start at all without starter fluid, a clogged carburetor is often the culprit. Old fuel leaves behind varnish and deposits that block the tiny passages inside the carb.

2. Engine Surging — Does your mower rev up and down on its own while running? This surging or hunting is a classic sign of a partially clogged carburetor. The engine is starving for fuel, then getting too much, then starving again.

3. Black Smoke from the Exhaust — Black smoke means your engine is running rich — too much fuel, not enough air. This can happen when the air filter is clogged, but it's also a sign of carburetor problems, particularly a stuck float or worn needle valve.

4. Poor Performance or Stalling — If your mower bogs down when you hit thick grass or stalls on hills, the carburetor may not be delivering enough fuel under load. Partially blocked jets restrict fuel flow when the engine needs it most.

5. Fuel Leaking from the Carburetor — Visible fuel dripping from the carburetor body is a sign of a stuck float valve or deteriorated gaskets. This is a fire hazard and should be addressed immediately.

Most carburetor issues stem from one root cause: old fuel. Gasoline starts breaking down after about 30 days and can leave behind gummy deposits that clog carburetor passages. This is especially common in mowers that sit over winter with fuel in the tank.

Prevention is simple: use fuel stabilizer in your gas, run the carburetor dry before storing for the season, and use fresh fuel each spring. If you're already experiencing these symptoms, bring your mower to Cherrone Equipment Service. A professional carburetor cleaning costs far less than a replacement and usually solves the problem completely.