1984 Toyota 4Runner BaseFACTORY OEM SERVICE PROCEDURE

Electronic Fuel Injection (EFI)

All models are equipped with Bosch AFC fuel injection system. An electric fuel pump provides fuel to the fuel pressure regulator. From the regulator, fuel flows under pressure to the fuel injectors. The pressure regulator maintains uniform pressure differential at all times.

The constant pressure differential allows the ECU to control length of injection rather than amount of injection. The ECU monitors engine operating conditions and calculates injection duration for efficient engine operation.

The ECU activates all the injectors at the same time. When the injectors are activated, they provide 1/2 the amount of fuel required for ideal combustion with each engine revolution.

Fig 1: Electronic Control System Schematic
G42176Courtesy of Β© TOYOTA, LICENSE AGREEMENT TMS1002
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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