Fuel Delivery System
The content of this article reflects the changes called out by TSB 26-03-00.FUEL DELIVERY SYSTEM
The fuel delivery system consists of: the electric fuel pump, fuel filter, fuel pressure regulator, fuel tubes/lines/hoses, fuel rail, fuel injectors, fuel tank, accelerator pedal and throttle cable.
The in-tank fuel pump module contains the fuel pump, level sensor and fuel pressure regulator. The pump and regulator are serviced as part of the fuel pump module. Refer to Fuel Pump Module.
The fuel delivery system contains a in-tank life time fuel filter. The fuel filter is designed to last the life of the vehicle. No maintenance is required of the fuel filter.
A fuel return system is used on all models. Fuel is returned through the fuel pressure regulator within the fuel pump module.
The fuel tank assembly consists of: the fuel tank, filler tube, fuel gauge sending unit/electric fuel pump module, rollover valve, ORVR control valve, fuel fill check valve, and a pressure-vacuum filler cap.
Also to be considered part of the fuel system is the evaporation control system. This is designed to reduce the emission of fuel vapors into the atmosphere. The description and function of the Evaporative Control System is found in the Emission Control Systems.
LONG-TERM STORAGE
When storing your Dodge Viper for long periods, leave the fuel tank and fuel system full of fuel. For further information about long-term vehicle storage, refer to the Lubrication and Maintenance .
FUEL PUMP MODULE
The fuel pump module contains the fuel pump, fuel reservoir, level sensor, inlet strainer, fuel pressure regulator, and fuel filter. The level sensor is the only serviceable items. If the fuel pump, fuel pressure regulator, or fuel filter requires service, replace the fuel pump module.
ELECTRIC FUEL PUMP
The electric fuel pump is located in and is part of the fuel pump module. It is a positive displacement, gerotor type, immersible pump with a permanent magnet electric motor. The fuel pump module is suspended in fuel in the fuel tank.
The pump draws fuel through a strainer and pushes it through the motor to the outlet. The pump contains a check valve. The 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 dead- headed pressure output of approximately 880 kPa (130 psi). The regulator adjusts fuel system pressure to approximately 379 kPa (55 psi).
Fuel Pump Electrical Control
Voltage to operate the electric pump is supplied through the fuel pump relay. For an electrical operational description of the fuel pump refer to fuel Pump Relay - PCM Output.
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. The fuel level sensor (fuel gauge sending unit) sends a signal to the BCM and the BCM sends the signal over the PCI bus circuit to the PCM to indicate fuel level. The purpose of this feature is to prevent a false setting of misfire and fuel system monitor trouble codes if the fuel level is less than approximately 15 percent of its rated capacity. It is also used to send a signal for fuel gauge operation via the PCI bus circuits.
FUEL TANK
The fuel tank is equipped with fuel and vapor controls that allow the vehicle to pass a full 360° rollover without fuel leakage.
The fuel filler cap also acts as a pressure/vacuum valve. When air pressure inside the fuel tank gets too high or too low, the fuel cap valve 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. 1 Fuel Tank, Control Valve And Rollover Valve:
The ORVR control valve manages the flow of vapor during refueling. It also controls maximum fuel volume of the fuel tank (Fig. 1).
ONBOARD REFUELING VAPOR RECOVERY (ORVR)
ORVR System Schematic and components.
Fig. 2 ORVR System Schematic:
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 (Fig. 2). 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 while the On-Board diagnostics test is running, low level tank pressure can be trapped in the fuel tank and fuel can not be added to the tank until the pressure is relieved. 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. Removing the fuel cap and allowing enough time for the system to vent thru the recirculation tube.
CONTROL VALVE
It is a valve in the top of the fuel tank that controls fuel fill rate and fuel fill level and directs vapors to a storage area.
The valve controls the fuel fill rate and set the fuel level in the fuel tank. It also allows the proper operation of OBD II leak detection monitor. It prevent liquid fuel carry over into the EVAP system (Fig. 2).
FUEL RAIL/INTAKE MANIFOLD
The fuel system operates at approximately 379 kPa (55 psi).
The intake manifold contains the fuel passage for the injectors. Check fuel system pressure at the test port at the rear of the intake manifold on the passenger side.
Fig. 3 Fuel Injector:
FUEL INJECTORS
The fuel injectors are electrical solenoids (Fig. 3).
The injectors are positioned in the intake manifold with the nozzle ends directly above the intake valve port.
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 PRESSURE REGULATOR
A fuel pressure regulator is used on all gas powered engines. It is located inside the fuel pump module. It contains a diaphragm, calibrated springs and a fuel return valve.
The pressure regulator is a mechanical device that is calibrated to maintain fuel system operating pressure of approximately 379 kPa (55 psi) at the fuel injectors.
It contains a diaphragm, calibrated springs and a fuel return valve.
Fuel is supplied to the regulator by the electric fuel pump through an opening tube at the bottom of 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 56 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.
The pressure regulator is a mechanical device that is NOT controlled by the PCM or engine vacuum.
PRESSURE-VACUUM FILLER CAP
The fuel fill cap is threaded/quarter turn onto the end of the fuel filler tube. It's purpose is to retain vapors and fuel in the fuel tank.
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 10.9 to 13.5 kPa (1.6 to 2.0 psi) or vacuum of 1.0 to 2.0 kPa (0.15 to.29 psi) occurs in the fuel tank. When the pressure or vacuum is relieved, the valve returns to the normally closed position. The cap must be replaced by a similar unit if replacement is necessary
CAUTION: Remove the fuel filler cap to release fuel tank pressure before disconnecting any fuel system component.
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 Service Procedures 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.
Fig. 4 Typical Plastic Quick - Connect Fittings:
Fuel tubes connect fuel system components with plastic quick-connect fuel fittings. The fitting contains non-serviceable O-ring seals (Fig. 4).
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 (Fig. 4). When the fuel tube enters the fitting, the retainer locks the shoulder of the nipple in place and the O-rings seal the tube.
METAL QUICK CONNECT FITTINGS
The fuel filter outlet and fuel rail use metal quick-connect fittings. The fitting contains non-serviceable sealed O-rings. The fittings contain a plastic disconnect tool (release ring). Use special tool 6751 to disconnect and connect the fittings at the fuel rail.
Special tool 6751 could also be used at the fuel filter outlet.
Fig. 5 Metal Quick - Connect Fittings:
The quick-connect fitting consists of the O-rings, casing, disconnect tool and a retainer (Fig. 5). When the fuel tube enters the fitting, the retainer locks the shoulder of the nipple in place and the O-rings seal the tube.
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.
When installing fuel tubes, route them in the holders along the frame rail, fuel tank and the rear of the engine.
ROLLOVER VALVE
All vehicles have a rollover valves on top of the fuel tank.
The rollover valve on the fuel tank is a non-serviceable part.
The valves prevent fuel flow through the fuel tank vent valve hoses should the vehicle rollover.
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.
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 lines/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 leaks.
Use new original equipment type hose clamps.