FUEL SYSTEM
7-4
3TNV88F Service Manual
Before You Begin Servicing
• When the cold start device is activated, you may
notice a slight increase in the exhaust smoke of
the engine during engine warm-up.
Electronically controlled engines use a Cold Start
Device (CSD) that consists of a fuel injection
pump complete with a solenoid valve
(Figure 7-1, (1))
.
Figure 7-1
• When the engine is started with the cooling water
sensor detecting a low water temperature of 10
°C or lower and the E-ECU receives the
corresponding signal, then the E-ECU causes the
CSD’s solenoid valve to increase the injection
rate and advance the injection timing.
• Because of this, the engine speed increases by
approximately 75 min
-1
while the CSD is
operating. When the water temperature becomes
10 °C or higher, the CSD is turned off and the
engine returns to the normal speed.
Trochoid Fuel Pump
Note: The trochoid fuel pump located on the side
of the MP fuel injection pump is not a “fuel
supply” pump. The function of this pump is to
raise the pressure of the fuel supplied by the
electric fuel supply pump to the internal fuel
pressure required by the MP fuel injection
pump.
The use of an electric fuel supply pump is required
on all TNV model engines with the MP fuel injection
pump.
Electronically Controlled Governor
Electronically controlled engines are quipped with
an electronically controlled governor called “Eco
Governor”. Combined with the rack actuator
(Figure 7-1, (3))
, engine speed sensor
(Figure 7-1, (5))
, and other parts, the electronically
controlled governor communicates with the engine
controller (E-ECU), whereby the engine speed and
fuel injection rate are controlled.
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