Fuel Charging and Controls

Fuel Charging And Controls

COMPONENT LOCATIONS

Fuel Charging And Controls:

INTRODUCTION
The major components of the fuel charging and control system comprise a fuel pump and Fuel Pump Driver Module (FPDM), fuel rails and eight injectors. The fuel pump supplies fuel from the tank, via a pipe routed along the side of the transmission, to the fuel rail. The fuel rail distributes the fuel equally to each of the 8 injectors. The fuel injectors, which are controlled by the Engine Management System (EMS), are installed in the fuel rails on each side of the air intake manifold. A cross over pipe connects the 2 fuel rails together at the front of the engine.

FUEL PUMP







The fuel pump module is mounted in the RH side of the saddle type fuel tank and delivers fuel at variable flow and pressure to the fuel rails, which supply fuel to all fuel injectors. The fuel pump operation is regulated by the FPDM, which is controlled by the EMS.

FUEL PUMP DRIVER MODULE







The Fuel Pump Driver Module (FPDM) is used to control the speed of the fuel pump based upon the fuel demand of the engine. The ECM controls the FPDM in response to inputs from the fuel rail pressure sensor, MAP and the Mass Air Flow (MAF)/Intake Air Temperature (IAT) sensor. The FPDM is located on the RH end of the charcoal cannister and is attached by 2 scrivet fasteners.

The ECM sends a PWM signal to the FPDM, the frequency of the signal determines the duty cycle of the pump. The PWM signal to the pump represents half the ON time of the pump. If the ECM transmits a 50% on time the drives the pump at 100%. If the ECM transmits a 5% ON time the FPDM drives the pump at 10%. The FPDM will only turn the fuel pump ON if it receives a valid signal between 4% and 50%. When The ECM requires the fuel pump to be turned OFF the ECM transmits a duty cycle signal of 75%.

The status of the FPDM is monitored by the ECM. Any errors can be retrieved from The ECM using Integrated Diagnostic System (IDS). The FPDM cannot be interrogated for diagnostic purposes.

INJECTORS







Eight, top fed, 12 hole, fuel injectors are installed in the fuel rails. Two 'O' rings seal each injector to the fuel rails and should be renewed whenever an injector is refitted to an engine. A small amount of engine oil can be applied to the 'O' rings to aid installation. No other form of lubrication should be used. The fuel jets from the injectors are directed onto the back of the intake valves.

The injectors are electromagnetic solenoid valves controlled by the ECM. Each injector contains a solenoid-operated needle valve, which is closed while the solenoid winding is de-energized. The solenoid winding is connected to a power feed from the main relay and to an earth through the ECM. The ECM switches the earth to control the opening and closing of the needle valve. While the needle valve is open, fuel is sprayed into the cylinder intake tract onto the back of the intake valves. The ECM meters the amount of fuel injected by adjusting the time that the needle valve is open.

The injectors have a resistance of 13.8 Ohms ± 0.7 Ohms @ 20 Degrees Celsius.

ELECTRIC THROTTLE







The electronic throttle body controls the engine torque and is located on the induction elbow at the rear of the engine. Its main components are an electronic throttle control valve, Accelerator Pedal Position (APP) sensor and the Engine Control Module (ECM).

The APP sensor determines the driver demand to control throttle opening. This value is received by the ECM and the throttle is then opened to the correct angle by means of an integral electric motor. Sensors in the throttle body are used to determine the position of the throttle plate and the rate of change in its angle.

FUEL RAILS







Each fuel rail maintains a fuel pressure of typically 4.5bar (65 psi), however, this pressure will vary depending on engine requirements; lower at idle, higher at full load. Four fuel injectors are installed in each cylinder head and are connected to the fuel rail. 'O' ring seals are used to seal the injectors to the fuel rails.

FUEL PRESSURE DAMPER







A fuel pressure damper is attached centrally to each of the fuel rails. The damper acts to damp pressure pulses from the fuel pump.

FUEL TEMPERATURE SENSOR







The fuel temperature sensor is located in the rear of the RH fuel rail. The sensor is an NTC sensor, which is connected to the ECM by two wires.

FUEL RAIL PRESSURE SENSOR







The fuel pressure sensor continuously monitors the fuel pressure in the fuel rail, this value is used by the ECM to calculate the injector pulse-width required to deliver the correct mass of fuel per injection.

The ECM also uses this information to demand a specific fuel flow-rate from the fuel pump via the FPDM.