91 excel injectors sensor on 1991 Hyundai Excel

I am working on a 91 excel, the fuel pump is running and I have gas after the filter to the injectors but I am not getting 12 volts to open the injectors? Where is the sensor and what sends voltage to energize the injectors.

1 answer
12 from ignition switch is constant with key on. the ground is controlled by ecm.it looks at the crank sensor for a trigger. you might want to start there.