The 1995 Toyota 4Runner fuel system is equipped with Multiport Fuel Injection (MFI) system. The MFI system is composed of three basic subsystems: Fuel, Air Induction and Electronic Control Systems. An electric fuel pump supplies sufficient fuel, under a constant pressure, to the MFI injectors. In accordance with signals from the ECM, these injectors inject the most appropriate quantity of fuel for the engine condition into the intake manifold. Each injector injects, at the same time, one half of the fuel required for ideal combustion with each engine revolution.
The air induction system provides just the right amount of air for the engine operating condition. The Multiport Fuel Injection (MFI) system receives signals from various sensors indicating changing engine operating conditions such as: Intake air volume; Intake air temperature; Coolant temperature; Engine rpm; Acceleration/deceleration Exhaust oxygen content etc. These signals are utilized by the ECM to determine the injection duration necessary for an optimum air–fuel ratio.