See Figures 1, 2, 3, 4, 5, 6 and 7
The Electronic Fuel Injector System (EFI) is classified as a multi-point, pulse time, mass air flow (EFI) or speed density control (SEFI) fuel injection system.
An on board vehicle electronic engine control (EEC) computer accepts inputs from various engine sensors to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range. The computer then outputs a command to the fuel injectors to meter the approximate quantity of fuel.
The fuel charging manifold assembly incorporates electrically actuated fuel injectors directly above each of the engine's intake ports. The injectors, when energized, spray a metered quantity of fuel into the intake air stream.
A constant fuel pressure drop is maintained across the injector nozzles by a pressure regulator. The regulator is connected in series with the fuel injectors and positioned down stream from them. Excess fuel supplied by the pump, but not required by the engine, passes through the regulator and returns to the fuel tank through a fuel return line.
All injectors are energized simultaneously, once every crankshaft revolution. The period of time that the injectors are energized (injector on-time or the pulse width) is controlled by the vehicles' Engine Electronic Control (EEC) computer.