Actuators - TOHATSU MFS 25D Service Manual

Fuel System (Fuel Injection)
5. Oil Pressure Switch
The oil pressure switch is located on the port side of the
engine block, protruding into the oil passage. The oil
pressure switch sends an oil pressure low signal to the
ECU.
The ECU activates the low speed ESG and warning lamp
based on this information.

2) Actuators

The actuator receives signals from the ECU to control the
air/fuel ratio, ignition advance angle and idle revolution
speed.
1. ISC (Idle Speed Control) Valve
ISC is also referred to as IAC (Idle Air Control). The ISC
valve is a solenoid valve with a built-in spring that is
operated electrically to control the air intake quantity that
bypasses the closed throttle valve. The opening of the ISC
valve varies between 0% to 100% to control the following
three functions according to signals from the ECU.
1. Increase the idle revolution speed during engine warm-
up by increasing the air intake when starting the engine.
2. Control the idle revolution speed according to varying
engine load and operating conditions.
3. Prevent the engine from stalling by increasing the air
intake (bypass) to function as a dash pot when the
throttle is closed quickly e.g. during sudden deceleration
etc.
2. Fuel Injector
The fuel injector is a solenoid valve with a built-in spring
that is operated electrically to feed fuel into the intake
manifold passage. Electricity is supplied from the ECU to
the injector, and high pressure fuel is injected by the ECU
closing the ground circuit and lifting the solenoid. The fuel
injector closes to stop injecting fuel when the ECU opens
the ground circuit.
3. Fuel Feed Pump (FFP)
Refer to the description of the vapor separator in Chapter 4.
4-20 4st 25/30 2022