Fuel Injectors
A fuel rail links the fuel pressure regulator with the fuel injectors. Each cylinder is provided with a solenoid-operated injector which sprays fuel towards back of each inlet valve. Each injector is energized through the ignition coil and grounded through the ECU to complete the circuit.
Each injector is linked to a resistor (resistor may be external or integral with injector or ECU) to reduce operating voltage to 3 volts and to protect injectors from power surges. The ECU controls the length of time each injector is open.
The "open" time of the injector governs the amount of fuel delivered. The injectors deliver 1/2 the amount of fuel required for an operating cycle each time they open (twice per cycle).