Dropping Resistor; Coolant Thermosensor; Pressure Regulator - Subaru XT 1988 Service Manual

2-7
FUEL INJECTION SYSTEM
Dropping Resistor
(1800 cc model only)
The dropping resistor serves as a voltage control to maintain
optimum injector driving current.
Coolant Thermosensor
The coolant thermosensor is equipped on the waterpipe which
is made of aluminum alloy. Its thermistor changes resistance
with respect to temperature.
To the MPFI control unit, the thermosensor sends the coolant
temperature signal which is decisive for the fuel volume to be
injected.
Fig.
14
c:
~
2.5
III
u
c:
~
'ij
a:
L--_ _
.l--_ _ _ _
Temp.
°c
(oF)
-20 0 40 80
(-4)(321 (104)
(176)
20 60
(68) (140)
A21-227
10
Pressure Regulator
The pressure regulator is divided into the fuel chamber and
the spring chamber by the diaphragm as illustrated below. Fuel
is fed to the fuel chamber through the fuel inlet connected
with the injector. A difference in pressure between the fuel
chamber and the spring chamber connected with the intake
manifold causes the diaphragm to be pushed down, and fuel
is fed back to the fuel tank through the return line.
By returning fuel so as to balance the above pressure differ-
ence and the spring force, the fuel pressure is kept at a con-
stant level 250.1 kPa (2.55 kg/cm2, 36.3 psi) against the in-
take manifold pressure.
(1800 cc model)
Fig. 15
Diaphragm
Diaphragm
Chamber
(2700 cc model)
To intake manifold
To intake manifold
t
Valve
Fig. 16
¢:>
Fuel inlet
Diaphragm
. . :~om fuel
Injector
A21-218
L2-1472