A method of controlling fuel supplied to an engine is provided. The engine includes at least one cylinder having a port injection fuel injector being supplied with fuel from at least one of a first fuel storage tank and a second fuel storage tank and a direct injection fuel injector being selectively supplied with fuel from one of the first fuel storage tank and the second fuel storage tank. The method includes at a first condition, supplying at least some of a second type of fuel from the second fuel storage tank to the direct injection fuel injector and supplying at least some of a first type of fuel from the first fuel storage tank to the port injection fuel injector, and at a second condition, supplying at least some of the first type of fuel from the first fuel storage tank to the direct injection fuel injector.