The Electronic Fuel Injection module is present in many cars, assuming the role of carburetors. It is an electronic control unit that opens the fuel injectors.

This is a good explanation found in Wikipedia:

Central to an EFI system is a computer called the Engine Control Unit (ECU), which monitors engine operating parameters via various sensors.The ECU interprets these parameters in order to calculate the appropriate amount of fuel to be injected, among other tasks, andcontrols engine operation by manipulating fuel and/or air flow as wellas other variables. The optimum amount of injected fuel depends onconditions such as engine and ambient temperatures, engine speed and workload, and exhaust gas composition.

The electronic fuel injector is normally closed, and opens to inject pressurized fuel as long as electricity is applied to the injector's solenoid coil. The duration of this operation, called pulse width,is proportional to the amount of fuel desired.