Fuel Inlet

Fig. 2 Carburetor fuel bowl vent system:

The fuel inlet system maintains a specified fuel level in the fuel bowl, allowing the fuel metering system to deliver the correct air/fuel mixture to the engine. The fuel inlet needle position is controlled by a float and lever assembly hinged on the float pin. The amount of fuel entering the bowl is regulated by the distance the inlet needle is moved off its seat. When the float drops, it causes the inlet needle to drop and this allows additional fuel to enter the bowl. As the fuel level reaches a specified level, the inlet needle is raised to a position that will allow only enough fuel to enter to replace that being used by the metering systems. The float bowl uses a solenoid valve to operate the dual venting system, Fig. 2. When the ignition is On, the bowl is vented internally to the air cleaner. This balances the bowl with carburetor inlet air. When the ignition is Off, the bowl is vented externally, and fuel vapors are stored in the carbon canister to be drawn into the engine when the engine is started.