US Patent 12006887 Mixed fuel engine

A system, method and circuit restricts the amount of a first fuel being provided to a duel-fuel engine, for example a diesel-natural gas engine; wherein a secondary circuit is provided, in parallel, to the circuit formed between the engine control unit, first fuel injector, and ground comprising a dummy load, and a normally closed switch inserted in the first fuel injection circuit; such that when the normally open switch is in a closed state the dummy load provides a resistance to the second sub-circuit, such that a total resistance in the second sub-circuit is equal to a total resistance in the first sub-circuit when the normally closed switch is in a closed state.