Fuel supply system and method for supplying fuel

A fuel supply system for supplying composite fuel containing alcohol and gasoline to a plurality of cylinders of an internal combustion engine, the composite fuel including main-fuel and sub-fuel, the sub-fuel being lower than main-fuel in concentration of alcohol, the fuel supply system comprising:

• a plurality of first fuel injection valves each provided correspondingly to each of the plurality of cylinders and configured to inject fuel;
• a plurality of second fuel injection valves each provided correspondingly to each of the plurality of cylinders and configured to inject fuel;
• a fuel inlet portion configured to supply at least sub-fuel to each of the plurality of first fuel injection valves and each of the plurality of second fuel injection valves;
• and
• selector control means for selecting one of main-fuel and sub-fuel supplied through the fuel inlet portion to a controlled valve,
• wherein the controlled valve includes each of the plurality of first fuel injection valves.