Fuel Delivery System
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/lines/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 for recommended fuel filter replacement intervals.
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. 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.
FUEL LEVEL SENSOR
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
All models pass a full 360 degree rollover test without fuel leakage. To accomplish this, fuel and vapor flow controls are required for all fuel tank connections.
All models are equipped with either one or two rollover valves mounted into the top of the fuel tank (or pump module).
An evaporation control system is connected to the rollover valve(s) to reduce emissions of fuel vapors into the atmosphere. When fuel evaporates from the fuel tank, vapors pass through vent hoses or tubes to a charcoal canister where they are temporarily held. When the engine is running, the vapors are drawn into the intake manifold. Certain models are also equipped with a self-diagnosing system using a Leak Detection Pump (LDP). Refer to the Emission Control System for additional information.
FUEL INJECTORS
Fuel Injector Location - Typical:
The injectors are positioned in the cylinder heads with the nozzle ends directly above the intake valve port.
Fuel injectors are not interchangeable between engines.
Fuel Injector:
The fuel injectors are 12 ohm electrical solenoids. 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.
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.
Side View - Filter/Regulator:
It contains a diaphragm, calibrated springs and a fuel return valve. The internal fuel filter 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.
ORVR System Schematic:
ORVR System:
ON-BOARD REFUELING VAPOR RECOVERY
The emission control principle used in the ORVR system is that the fuel flowing into the filler tube (appx. 1" I.D.) creates an aspiration effect which draws air into the fill tube. During refueling, the fuel tank is vented to the vapor canister to capture escaping vapors. With air flowing into the filler tube, there are no fuel vapors escaping to the atmosphere. Once the refueling vapors are captured by the canister, the vehicle's computer controlled purge system draws vapor out of the canister for the engine to burn. The vapors flow is metered by the purge solenoid so that there is no or minimal impact on driveability or tailpipe emissions.
As fuel starts to flow through the fill tube, it opens the normally closed check valve and enters the fuel tank. Vapor or air is expelled from the tank through the control valve to the vapor canister. Vapor is absorbed in the canister until vapor flow in the lines stops, either following shut-off or by having the fuel level in the tank rise high enough to close the control valve. The control valve contains a float that rises to seal the large diameter vent path to the canister. At this point in the fueling of the vehicle, the tank pressure increase, the check valve closes (preventing tank fuel from spiting back at the operator), and fuel then rises up the filler tube to shut-off the dispensing nozzle.
If the engine is shut-off during the On-Board diagnostics test, low level tank pressure can be trapped in the fuel tank and fuel can not be added to the tank. This is due to the leak detection pump closing the vapor outlet from the top of the tank and the one-way check valve not allowing the tank to vent through the fill tube to atmosphere. Therefore, when fuel is added, it will back-up in the fill tube and shut off the dispensing nozzle. The pressure can be eliminated in two ways: 1. Vehicle purge must be activated and for a long enough period to eliminate the pressure. 2. The vacuum operated canister vent valve will quickly relieve the tank pressure to atmosphere when the engine is turned-off.
CONTROL VALVE/PRESSURE RELIEF
If the fuel tank should over-pressurize, the control valve incorporates a pressure relief port that allows pressure relief capability under extreme conditions. Example, if the canister vent line was to get pinched or obstructed, the relief valve would vent the pressure.
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 the Removal/installation for more information.
CAUTION: The interior components (O-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.
Plastic Quick Connect Fittings:
Fuel tubes connect fuel system components with plastic quick-connect fuel fittings. The fitting contains non-serviceable O-ring seals.
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 O-rings, retainer and casing. When the fuel tube enters the fitting, the retainer locks the shoulder of the nipple in place and the O-rings seal the tube.
ROLLOVER VALVES
All vehicles have rollover valve(s) on top of the fuel tank.
The valves prevent fuel flow through the fuel tank vent valve hoses should the vehicle rollover.
The rollover valves on the fuel tank are not serviceable.
FUEL TUBES/LINES/HOSES AND CLAMPS
Also refer to Quick-Connect Fittings.
WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE (EVEN WITH THE ENGINE OFF). BEFORE SERVICING ANY FUEL SYSTEM HOSES, FITTINGS OR LINES, THE FUEL SYSTEM PRESSURE MUST BE RELEASED. REFER TO THE FUEL SYSTEM PRESSURE RELEASE PROCEDURE.
Inspect all hose connections such as clamps, couplings and fittings to make sure they are secure and leaks are not present. The component should be replaced immediately if there is any evidence of degradation that could result in failure.
Never attempt to repair a plastic fuel line/tube. Replace as necessary.
Avoid contact of any fuel tubes/hoses with other vehicle components that could cause abrasions or scuffing. Be sure that the plastic fuel lines/tubes are properly routed to prevent pinching and to avoid heat sources.
The lines/tubes/hoses used on fuel injected vehicles are of a special construction. This is due to the higher fuel pressures and the possibility of contaminated fuel in this system. If it is necessary to replace these Tines/tubes/hoses, only those marked EFM/EFI may be used.
If equipped: The hose clamps used to secure rubber hoses on fuel injected vehicles are of a special rolled edge construction. This construction is used to prevent the edge of the clamp from cutting into the hose. Only these rolled edge type clamps may be used in this system. All other types of clamps may cut into the hoses and cause high-pressure fuel Teaks.
Use new original equipment type hose clamps. Tighten hose clamps to 3 N.m (25 in. lbs.) torque.