Fuel System
FUEL SYSTEMFUEL SYSTEM OUTLINE
The fuel system supplies the sequential multi-port fuel injection (SFI) fuel injectors with clean fuel at a controlled pressure. The powertrain control module (PCM) controls the fuel pump and monitors the fuel pump monitor (FPM) circuit. The PCM controls the fuel injector on/off cycle duration and determines the correct timing and amount of fuel delivered.
The hybrid vehicle uses the electronic returnless fuel system. The system consists of:
- a fuel tank with reservoir
- the fuel pump
- the fuel filter
- the fuel supply line
- the fuel rail pressure temperature (FRPT) sensor
- the fuel rail
- the fuel pump driver module (FPDM)
- and the fuel injectors.
1. The fuel delivery system is enabled during crank or running mode once the PCM receives a crankshaft position (CKP) sensor signal.
2. The PCM defines and implements the fuel pump logic.
3. The PCM commands a duty cycle to the Fuel Pump Driver Module (FPDM).
4. The FPDM modulates the voltage to the fuel pump required to achieve the proper fuel pressure. Voltage for the fuel pump is supplied by the FPDM.
5. The Fuel Rail Pressure Temperature (FRPT) sensor provides the PCM with the current fuel rail pressure and temperature. The PCM uses this information to vary the duty cycle output to the FPDM to compensate for varying loads.
6. The fuel injector is a solenoid operated valve that meters the fuel flow to each combustion cylinder. The injector is normally closed and and is operated by VPWR from the power relay. The ground signal is controlled by the PCM.
7. There are 3 filtering or screening devices in the fuel delivery system. The intake sock is a fine, nylon mesh screen mounted on the intake side of the fuel pump. There is a fuel filter screen located at the fuel rail side of the fuel injector. The fuel filter assembly is located between the fuel pump and the fuel rail.
8. The fuel pump module is a device that contains the fuel pump and the fuel sender assembly. The fuel pump is located inside the reservoir and supplies fuel through the fuel pump module manifold to the engine and the fuel pump module jet pump.
9. The front inertia fuel shut-off (IFS) switch is used to de-energize the fuel delivery secondary circuit in the event of a collision. The IFS switch is a safety device that should be reset only after a thorough inspection of the vehicle following a collision.
FUEL INJECTORS
The fuel injector is a solenoid operated valve that meters fuel flow to the engine. The fuel injector is opened and closed a constant number of times per crankshaft revolution. The amount of fuel is controlled by the length of time the fuel injector is held open.
The fuel injector is normally closed, and is operated by VPWR from the electronic engine control (EEC) power relay. The ground signal is controlled by the PCM.
The injector is the deposit resistant injection (DRI) type and does not have to be cleaned. However, it can be flow checked and, if found outside of specification, a new fuel injector should be installed.
FUEL PUMP DRIVER MODULE (FPDM)
The FPDM contains the fuel pump and sender assembly. The fuel pump is located inside the FPDM and supplies fuel through the FPDM manifold to the engine and FPDM jet pump. The jet pump continuously refills the reservoir with fuel, and a check valve located in the manifold outlet maintains system pressure when the fuel pump is not energized. A flapper valve located in the bottom of the reservoir allows fuel to enter the reservoir and prime the fuel pump during the initial fill.
FUEL RAIL PRESSURE TEMPERATURE (FRPT) SENSOR
The FRPT sensor measures the pressure and temperature of the fuel in the fuel rail and sends these signals to the PCM. The sensor uses the intake manifold vacuum as a reference to sense the pressure difference between the fuel rail and the intake manifold. A fuel return line to the fuel tank is not used in this type of fuel system. The relationship between fuel pressure and fuel temperature is used to determine the possible presence of fuel vapor in the fuel rail. Both pressure and temperature signals are used to control the speed of the fuel pump. The speed of the fuel pump maintains fuel rail pressure by keeping fuel in its liquid state. The dynamic range of the fuel injectors increases because of the higher rail pressure, which allows the injector pulse width to decrease.
INERTIA SWITCHES
There is a rear inertia switch in addition to a front inertia switch. Either one switch tripping results in a no start and a no crank condition.
- The front inertia switch cuts off both fuel and high voltage.
- The rear inertia switch cuts off power to the high voltage contactors located inside the battery case. In response to the loss of power at the contactors, the PCM shuts off fuel indirectly.
- The additional rear inertia switch disconnects faster which provides an extra margin of safety.
INERTIA SWITCH RESET PROCEDURE
1. Turn the ignition to LOCK
2. Check for fuel leaks
3. If no leaks are found, press the reset button on each front and rear inertia switch
4. Turn the ignition to RUN for a few seconds then turn it back to LOCK
5. Check for fuel leaks