THROTTLE BODY
The throttle body assembly is located on the left
end of the intake manifold plenum (Fig. 20). The
throttle body houses the throttle position sensor and
the idle air control motor. Air flow through the throt-
tle body is controlled by a cable operated throttle
blade located in the base of the throttle body.
FUEL SUPPLY CIRCUIT
Fuel is pumped to the fuel rail by an electrical
pump in the fuel tank. The pump inlet is fitted with
a strainer to prevent water and other contaminants
from entering the fuel supply circuit.
Fuel pressure is controlled to a preset level above
intake manifold pressure by a pressure regulator.
The regulator is mounted on the fuel rail (Fig. 21).
The regulator uses intake manifold pressure as a ref-
erence.
FUEL INJECTORS AND FUEL RAIL ASSEMBLY
Four fuel injectors are retained in the fuel rail by
lock rings. The rail and injector assembly are in-
stalled with the injectors inserted into recessed holes
in the intake manifold.
FUEL PRESSURE REGULATOR
The pressure regulator is a mechanical device lo-
cated on the fuel rail, downstream of the fuel injec-
tors (Fig. 22). The regulator maintains a constant
380 kPa (55 psi) across the fuel injector tip.
The regulator contains a spring loaded rubber dia-
phragm that covers the fuel return port. When the
fuel pump is operating, fuel flows past the injectors
into the regulator, and is restricted from flowing any
further by the blocked return port. When fuel pres-
sure reaches 380 kPa (55 psi) it pushes on the dia-
phragm, compresses the spring, and uncovers the
fuel return port. The diaphragm and spring con-
stantly move from an open to closed position to keep
the fuel pressure constant.
Fig. 21 Fuel Supply Circuit
Fig. 22 Fuel Pressure Regulator
14 - 94
FUEL SYSTEMS
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