Fuel Delivery and Air Induction: Description and Operation
FUEL DELIVERY SYSTEMThe front wheel drive car uses a plastic fuel tank located rear center of the vehicle.
The Fuel Delivery System consists of: the electric fuel pump module, fuel filter, tubes/tines/hoses, fuel rail, and fuel injectors.
The in-tank fuel pump module contains the fuel pump. The pump is serviced as part of the fuel pump module. Refer to Fuel Pump Module.
The fuel filter is replaceable, it is a combination fuel pressure regulator/filter on the fuel pump module. Refer to the Maintenance Schedules in the Introduction section of this manual for recommended fuel filter replacement intervals.
Fig 1 Fuel Pump Module -- Typical:
FUEL PUMP MODULE
The fuel pump module contains the fuel pump, fuel reservoir, level sensor, inlet strainer, and fuel pressure regulator/filter (Fig. 1). The inlet strainer, level sensor and fuel pressure regulator/filter are the only serviceable items. If the fuel pump requires service, replace the fuel pump module.
ELECTRIC FUEL PUMP
The fuel system uses a positive displacement, gerotor gear, immersible pump with a permanent magnet electric motor. The pump draws fuel through a strainer and pushes it through the motor to the outlet. Check Valve Operation: The pump outlet contains a one-way check valve to prevent fuel flow back into the tank and to maintain fuel supply line pressure (engine warm) when pump is not operational. It is also used to keep the fuel supply line full of gasoline when pump is not operational. After the vehicle has cooled down, fuel pressure may drop to 0 psi (cold fluid contracts), but liquid gasoline will remain in fuel supply line between the check valve and fuel injectors. The fuel pump relay provides voltage to operate the fuel pump.
[1][2]FUEL LEVEL SENSOR
This procedure tests the resistance of the level sensor itself. It does not test the level sensor circuit. Refer to Wiring Diagrams for circuit identification.
The level sensor is a variable resistor. Its resistance changes with the amount of fuel in the tank. The float arm attached to the sensor moves as the fuel level changes.
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.
Fuel delivery system contains a fuel tank rollover valve. The valve is mounted on top of the fuel tank. The valve functions as a tank pressure control valve while the vehicle is upright, but contains a check valve that prevents fuel from escaping 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 evaporation into the atmosphere and reduces unburned hydrocarbons. Vapors from the fuel tank are collected in a charcoal filled canister. The vapors are held in the canister until the engine is operating. When the engine is running, the vapors are drawn through the intake manifold into the combustion chambers.
Fig 2 Fuel Injector:
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 2 streams. The spraying action atomizes the fuel, adding it to the air entering the combustion chamber. The injectors are positioned in the cylinder heads. Fuel injectors are not interchangeable between engines.
Fig 3 Fuel Injector Location -- Typical:
The injectors are positioned in the cylinder heads with the nozzle ends directly above the intake valve port (Fig. 3).
Fig 4 Side View -- Filter/Regulator:
FUEL FILTER/FUEL PRESSURE REGULATOR
A combination fuel filter and fuel pressure regulator is used on all gas powered engines. It is located ~ on the top of the fuel pump module. A separate frame mounted fuel filter is not used.
Fuel Pressure Regulator Operation: The pressure regulator is a mechanical device that is calibrated to maintain fuel system operating pressure of approximately 338 kPa (49 psi) at the fuel injectors.
It contains a diaphragm, calibrated springs and a fuel return valve. The internal fuel filter (Fig. 4) is also part of the assembly.
Fuel is supplied to the filter/regulator by the electric fuel pump through an opening tube at the bottom of filter/regulator.
The fuel pump module contains a check valve to maintain some fuel pressure when the engine is not operating. This will help to start the engine.
If fuel pressure at the pressure regulator exceeds approximately 49 psi, an internal diaphragm closes and excess fuel pressure is routed back into the tank through the pressure regulator. A separate fuel return line is not used with any gas powered engine.
PRESSURE-VACUUM FILLER CAP
The fuel filler cap incorporates a two-way relief valve that is closed to atmosphere during 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 in. Hg) occurs in the fuel tank. When the pressure or vacuum is relieved, the valve returns to the normally closed position.
CAUTION: Remove the fuel filler cap to release fuel tank pressure before disconnecting any fuel system component.
Fig 5 Plastic Quick-Connect Fittings:
QUICK-CONNECT FITTINGS
Different types of quick-connect fittings are used to attach various fuel system components. These are: a single-tab type, a two-tab type or a plastic retainer ring type. Some are equipped with safety latch clips. Refer to Service and Repair for more information.
CAUTION: The interior components (0-rings, spacers) of quick-connect fitting are not serviced separately. Do not attempt to repair damaged fittings or fuel lines/tubes. If repair is necessary, replace the complete fuel tube assembly.
Fuel tubes connect fuel system components with plastic quick-connect fuel fittings. The fitting contains non-serviceable 0-ring seals (Fig. 5).
CAUTION: Quick-connect fittings are not serviced separately. Do not attempt to repair damaged quick-connect fittings or fuel tubes. Replace the complete fuel tube/quick-connect fitting assembly.
The quick-connect fitting consists of the 0-rings, retainer and casing (Fig. 5). When the fuel tube enters the fitting, the retainer locks the shoulder of the nipple in place and the 0-rings seal the tube.
ROLLOVER VALVE
The fuel tank has fuel and vapor controls that allow the vehicle to pass a full 360 rollover without fuel leakage.
NOTE: The Evaporation Control System, is also considered part of the fuel system. The system reduces the emission of fuel vapor into the atmosphere.