Fuel injection system for an internal combustion engine of a vehicle and a fuel injection method

A fuel injection system, for an internal combustion engine, the fuel injection system comprising:

• a first fuel injector, configured to be connected to a high-pressure fuel source,
• a second fuel injector, configured to be connected to a low-pressure fuel source,
• an intake pre-chamber, configured to receive fuel injected by the first fuel injector and fuel injected by the second fuel injector,
• an intake nozzle, configured to receive fuel from the intake pre-chamber and to inject said fuel in a combustion chamber of the internal combustion engine,
• a spark plug positioned inside the pre-chamber and configured for igniting the fuel injected by the first fuel injector or second fuel injector, and
• a controller, connected to the first fuel injector, to the second fuel injector and to the spark plug, for controlling a fuel injection by the first fuel injector into the intake pre-chamber, a fuel injection by the second fuel injector into the intake pre-chamber, and the spark plug, as a function of a requested torque for the internal combustion engine and as a function of an availability of fuel at the high-pressure fuel source and the low-pressure fuel source.