Chrysler 1998 Viper RT/10 Owner's Manual page 718

1 4 - 4 FUEL SYSTEM S R
D E S C R I P T I O N A N D O P E R A T I O N ( C o n t i n u e d )
W A R N I N G : R E L E A S E F U E L S Y S T E M P R E S S U R E
B E F O R E S E R V I C I N G T H E F U E L T A N K , F U E L PUMP,
F U E L T U B E S , F U E L F I L T E R , F U E L I N J E C T O R S O R
F U E L P R E S S U R E R E G U L A T O R . F O L L O W T H E
F U E L S Y S T E M P R E S S U R E R E L E A S E P R O C E D U R E
T O R E L I E V E F U E L S Y S T E M P R E S S U R E .
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 a r m move up. This decreases
the sending u n i t resistance, causing the fuel gauge
on the instrument panel to read full.
FUEL PRESSURE REGULATOR
A fuel pressure regulator is used on a l l gas pow-
ered engines. I t is located on the top of the fuel pump
module. A separate frame mounted fuel filter is used.
F u e l P r e s s u r e R e g u l a t o r O p e r a t i o n : The pres-
sure regulator is a mechanical device t h a t is cali-
brated to m a i n t a i n fuel system operating pressure of
approximately 379 kPa (55 psi) at the fuel injectors.
I t contains a diaphragm, calibrated springs and a
fuel r e t u r n valve. The i n t e r n a l fuel filter is also p a r t
of the assembly.
Fuel is supplied to the filter/regulator by the elec-
tric fuel pump through an opening tube at the bot-
tom of filter/regulator.
The fuel pump module contains a check valve to
m a i n t a i n some fuel pressure w h e n the engine is not
operating. This w i l l help to start the engine.
I f fuel pressure at the pressure regulator exceeds
approximately 56 psi, an i n t e r n a l diaphragm closes
and excess fuel pressure is routed back into the t a n k
t h r o u g h the pressure regulator. A separate fuel
r e t u r n line is not used w i t h any gas powered engine.
The pressure regulator is a mechanical device t h a t
is N O T controlled by the P C M or engine vacuum.
FUEL TANK
The fuel tanks of all Chrysler Motors built vehicles
are equipped w i t h fuel and vapor controls that allow the
vehicle to pass a full 360° rollover without fuel leakage.
The fuel delivery systems contain a fuel t a n k roll-
over valve. The valve is mounted on the fuel pump
module. The valve contains a check valve t h a t pre-
vents fuel from escaping from the fuel t a n k w h e n the
vehicle is t u r n e d over.
The fuel filler cap also acts as a pressure/vacuum
valve. When air pressure inside the fuel t a n k gets too
h i g h or too low, the fuel filler cap opens to relieve the
difference i n pressure.
A n evaporation control system restricts fuel evapo-
r a t i o n into the atmosphere and reduces unburned
hydrocarbons. Vapors from the fuel t a n k are collected
i n a charcoal filled canister. The vapors are held i n
the canister u n t i l the engine is operating. When the
engine is r u n n i n g , the vapors are d r a w n through the
intake manifold into the combustion chambers.
FUEL RAIL/INTAKE MANIFOLD
The fuel system operates at approximately 379 kPa
(55 psi). Check fuel system pressure at the test port
on the rear of the intake manifold.
The intake manifold contains the fuel passage for
the injectors. The fuel passage has a test port at the
rear of the intake manifold on the passenger side.
FUEL INJECTORS
The fuel injectors are 12 ohm electrical solenoids
(Fig. 1). The injector contains a pintle t h a t 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 h i g h
pressure, a fine spray is developed i n the shape of a
hollow cone. The spraying action atomizes the fuel,
adding i t to the air entering the combustion chamber.
The injectors are positioned i n the intake manifold.
UPPER
O-RING
LOWER
O-RING 9314-64
Fig. 1 Fuel Injector
The injectors are positioned i n the intake manifold
w i t h the nozzle ends directly above the intake valve
port.
PRESSURE-VACUUM FILLER CAP
The fuel filler cap incorporates a two-way relief
valve t h a t is closed to atmosphere d u r i n g normal
operating conditions. The relief valve is calibrated to
open when a pressure of 10 kPa (1.5 psi) or vacuum
of 6 kPa (1.8 i n . Hg) occurs i n the fuel tank. When
the pressure or vacuum is relieved, the valve returns
to the normally closed position.
C A U T I O N : R e m o v e t h e fuel filler c a p to r e l e a s e
fuel t a n k p r e s s u r e before d i s c o n n e c t i n g a n y fuel
s y s t e m c o m p o n e n t .