The present invention provides a fuel control apparatus with a modular fuel pressure modifying mechanism (i.e., a fuel metering section) and modular fuel regulator mechanism (i.e.. r fuel regulator section) that can each be calibrated independently of each other, and independent from the modular air passage mechanism (i.e., an airflow section). The air passage mechanism has an air intake end and an air outlet end and is constructed and arranged to accommodate airflow therethrough. the air passage mechanism having a first surface portion formed on an outer surface thereon. The modular fuel pressure modifying mechanism is constructed and arranged to receive fuel from a supply and deliver a portion of the hid at a pressure that is different from the pressure of the fuel supply, the modular fuel pressure modifying mechanism being removably mountable to the first surface portion of the air passage mechanism. The modular fuel pressure modifying mechanism is constructed and arranged to he calibrated prior to being mounted to the air passage mechanism. The fuel regulator mechanism is constructed and arranged to communicate with the airflow in the air passage mechanism and the modular fuel pressure modifying mechanism to regulate an amount of fuel delivered to the engine. The modular fuel pressure modifying mechanism and the modular fuel regulator mechanism are removably mountable to the modular air passage mechanism independently from each other.