How to Check a Lawn Mower Carb for Air Leaks

The carburetor, or "carb," on your lawnmower draws air into the engine. There are a few telltale signs to determine if your lawnmower has a carburetor leak. Idle speed, stalling, engine pops and noises are the most common signs of a carburetor leak. You don’t have to be a lawnmower technician to diagnose your carburetor. You can do it with minimal knowledge of the unit.

Socket wrench
Rag
Vacuum guage

Instructions

- 1
  Open the lawn mower by removing the bolts that keep the unit casing on the mower with a socket wrench. Locate the carburetor. This is a small metallic object next to the engine.
- 2
  Locate the idle screw on the right side of the carburetor and turn it counterclockwise. Crank the mower and allow it to run idle. If the mower stalls after multiple attempts to lower the idle, you probably have a leak in your carburetor.
- 3
  Use a rag to clean the idle screw on the side of the carburetor. If the screw has gunk or dirt on it, the carburetor will not be able to bring enough air into the carburetor.
- 4
  Crank the mower and listen for engine pops or a complete misfire to determine if the carburetor is drawing too much air into it, causing a leak.
- 5
  Connect a vacuum gauge to the carburetor and crank the engine. Use the vacuum measurement chart provided with the tool to determine if there is a leak in the system.

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