Blower: Engine Rpm's Surge Up And Down

Inside your leaf blower, there is an O-ring seal between the carburetor and the engine. The carburetor regulates the ratio of air and fuel that enters the engine. The seal created by the O-ring is extremely important because if extra air enters the mixture after the carburetor, the ratio will become lean, which increases the engine RPMs. Because the air doesn’t enter the engine in a controlled or consistent manner, it will cause the RPMs to surge up and down uncontrollably, depending on how lean the mixture is at any given moment. This is a serious condition, as a lean fuel mixture won’t properly lubricate a 2-cycle engine, which will cause costly damage to the cylinder and piston.

Like the function of the O-ring, the function of the gasket on your leaf blower is to create a seal. There will be a gasket (or O-ring) between the carburetor and the insulator, and another one between the insulator and the engine. If the gasket is damaged, it can allow extra air into the engine, causing it to run lean, and the RPMs will surge. As mentioned in our O-ring description, the extra air entering the engine can be a serious problem and can cause costly damage to the cylinder and piston. Be sure to troubleshoot immediately if you notice your engine RPMs surging up and down. Gaskets are designed for one-time use, so once you’ve removed the gasket, it will need to be replaced. Before installing the new gasket, be sure to clean the surface area of the carburetor, to ensure a proper seal.

The insulator is a plastic block that mounts between the carburetor and engine to insulate the carburetor from engine heat. As the function of the carburetor is to regulate the fuel/oil/air mixture that enters the engine, a damaged insulator can cause additional air to enter the engine uncontrollably. As with a damaged gasket or O-ring, the additional air will cause the engine to run lean and the RPMs to surge up and down. This is a serious issue and can result in long-term damage to the engine.