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14-20
FUEL
SYSTEM
Po .... 5uppl¥ and
fuol
l'urnp Con_I fIool 'u"",
Diooho,go
VolI" ...
Cootrol
I
Full _ . ' "
eo.ltol.
TIotbo
M
....
ConItol.
A~
fI
_ _ ., _
R_
Con_
POWER SUPPLY AND FUEL PUMP CONTROL
Power supply control to Ihe injector. air flow
sensor.
ISC
servo. etc. is
the
same as in the
conventional
6G72-S0HC erlgioo.
Ignition
,witch
Control
'
~
I
o
y
R
••
islor
M
Fuel
pun-v
Batt
~
ry
Fl>Ol
po,lmp
rolay
No.
2
""
...
'
Fuel pump control for controlling power supply to
the fuel pump is also the same as
in
the
conventional 6G72-S0HC engine.
FUEL PUMP DISCHARGE
VOLUME CONTROL
Fuel pump discharge volume
is
controlled in two
steps according to the amount 01 intake air
(engine load) in
1
cylinder in 1 cycle for improved
reliability of
the
fuel
pump. When tha amount of
intake air in this 1 cylinder 1 cycle
is
small
(engine
load is
low). the erlgine control unit turns
on
the
power transistor so current flows
in
the
coil 01 fuel pump relay No.2. As a
result.
the
relay switch changes Irom A to 8 (refer
to
the
figure on the
lelt.).
and current flows via the
resistor to the
fuel
pump motor.
The supply
voltage to the fuel pump
is reduced
since the
voltage
is
lowered by the resistor. pump speed
falls and the amount 01
fuel
discharged from the
fuel pump is redUCed_
VVhen the amount of intake
air
in this 1 cylinder 1
cycle is large (engine load
is
high). the engine
control unit turns off the power trMsistor aoo
changes the relay switch from 8
to
A (refer to the
figure on
the lef1.1.
As a result. voltage drop due
to the resistor ceases. pump speed rises and
the
amount of luel discharged from the fuel pump
Increases.
FUEL PRESSURE CONTROL
<Turbo>,
TURBO METER CONTROL
<Turbo>,
AIR FLOW SENSOR FILTER RESET CONTROL
These controls
are the
same as ill the
conventional 4G63·DOHC engiroe.
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