Fuel Injection System and Method of Controlling a Fuel Injection System

A fuel injection system for an internal combustion engine is provided. The fuel injection system comprises a primary fuel injector, a sensor, at least one secondary fuel injector and a controller. The primary fuel injector is configured to inject fuel into an ignition chamber of the internal combustion engine. The sensor is coupled to the primary fuel injector, wherein the sensor is configured to sense a fuel pressure of the fuel being injected by the primary fuel injector throughout each injection cycle of the primary fuel injector. The at least one secondary fuel injector is configured to inject fuel into a respective ignition chamber of the internal combustion engine. The controller is configured to receive data indicative of the fuel pressure value throughout each injection cycle. The controller is configured to determine a fuel quantity drift parameter over a plurality of fuel injection cycles based on the data indicative of the fuel pressure value. The controller is configured to adjust a fuel quantity delivered by the primary fuel injector and each secondary fuel injector based on the fuel quantity drift parameter.