To prevent plugging of a liquid fuel injection valve without estimating an in-cylinder temperature.
A fuel injection system includes: a first control device for outputting a first pulse signal specifying an energization time of a liquid fuel injection valve; and a second control device for generating a second pulse signal specifying an energization time of a gas fuel injection valve based on the first pulse signal in a gas fuel injection time, and outputting the second pulse signal to the gas fuel injection valve. The second control device, when detecting occurrence of fuel cutoff in the gas fuel injection time, carries out a cleaning mode of outputting the first pulse signal input from the first control device, to the liquid fuel injection valve after end of the fuel cutoff.
SHIMAZU TAKAYUKI
Tadashi Takahashi
Yoshifumi Saeki
Suzuki Mitsuyoshi
Yasuhiko Murayama