Chrysler 1998 Voyager Service Manual page 1299

NS
DESCRIPTION AND OPERATION (Continued)
check valve, in the pump outlet, maintains pump
pressure during engine off conditions. The fuel pump
relay provides voltage to the fuel pump.
The fuel pump has a maximum deadheaded pres-
sure output of approximately 635 kPa (95 psi). The
regulator adjusts fuel system pressure to approxi-
mately 338 kPa (49 psi).
FUEL PUMP ELECTRICAL CONTROL
Voltage to operate the electric pump is supplied
through the fuel pump relay. For an electrical opera-
tional description of the fuel pump refer to fuel Pump
Relay—PCM Output.
ELECTRICAL PUMP REPLACEMENT
The electric fuel pump is not serviceable. If the
fuel pump or electrical wiring harness needs replace-
ment, the complete fuel pump module must be
replaced. Perform the Fuel System Pressure Release
procedure before servicing the fuel pump.
FUEL LEVEL SENSOR
The level sensor is attached to the side of the fuel
pump module. The level sensor consists of a float, an
arm, and a variable resistor. As the fuel level
increases, the float and arm move up. This decreases
the sending unit resistance, causing the fuel gauge
on the instrument panel to read full.
FUEL PRESSURE REGULATOR
The fuel system uses a nonadjustable pressure reg-
ulator that maintains fuel system pressure at
approximately 338 kPa (49 psi), 3.3l uses approxi-
mately 379 kPa (55 psi). The fuel pressure regulator
contains a diaphragm, calibrated spring and a fuel
return valve. The spring pushes down on the dia-
phragm and closes off the fuel return port. System
fuel pressure reflects the amount of fuel pressure
required to open the return port.
The pressure regulator is a mechanical device that
is NOT controlled by the PCM or engine vacuum.
FUEL INJECTORS
The fuel injectors are 12 ohm electrical solenoids
(Fig. 2). The injector contains a pintle that closes off
an orifice at the nozzle end. When electric current is
supplied to the injector, the armature and needle
move a short distance against a spring, allowing fuel
to flow out the orifice. Because the fuel is under high
pressure, a fine spray is developed in the shape of a
hollow cone. The spraying action atomizes the fuel,
adding it to the air entering the combustion chamber.
The injectors are positioned in the intake manifold.
Fuel injectors are not interchangeable between
engines.
Fig. 2 Fuel Injector
The injectors are positioned in the intake manifold
with the nozzle ends directly above the intake valve
port (Fig. 3).
Fig. 3 Fuel Injector Location—Typical
FUEL TANK
The fuel tanks of all Chrysler Motors built vehicles
are equipped with fuel and vapor controls that allow
the vehicle to pass a full 360° rollover without fuel
leakage.
Front Wheel Drive fuel delivery systems contain a
fuel tank rollover valve. The valve is mounted on top
of the fuel tank. The valve functions as a tank pres-
sure control valve while the vehicle is upright, but
contains a check valve that prevents fuel from escap-
ing from the fuel tank when the vehicle is turned
over.
The fuel filler cap acts as a pressure/vacuum relief
valve. When air pressure inside the fuel tank gets too
high or too low, the fuel filler cap opens to relieve the
difference in pressure.
An evaporation control system restricts fuel evapo-
ration into the atmosphere and reduces unburned
FUEL SYSTEM 14 - 5