Description

Fuel Tank and Lines

NOTE:
A = Hardwired









OPERATION
The 2.0L GTDi fuel system uses a returnless fuel system. The fuel pump operation is regulated by the FPDM (fuel pump driver module), which is controlled by the ECM (engine control module). The FPDM (fuel pump driver module) regulates the fuel flow and pressure delivered to the engine mounted High Pressure (HP) fuel pump by controlling the operation of the fuel pump using PWM (pulse width modulation) output.
The pump operation is controlled by the ECM (engine control module) which uses signals from the Low Pressure (LP) fuel sensor to regulate the pump operation to maintain the optimum fuel pressure and flow.
Two fuel level sensors are connected to the CJB (central junction box). The CJB (central junction box) monitors the outputs from these sensors to determine the fuel level remaining in the fuel tank and to display the fuel level in the instrument cluster.

DESCRIPTION

Fuel System Schematic Diagram









FUEL TANK









The fuel tank is manufactured using six-layer co-extruded blow-molding technology providing both high mechanical strength and complete emissions integrity and is mounted under the rear seat floor pan, forward of the rear suspension. The fuel tank has a capacity of 70 liters (15.4 gallons).
The tank is a saddle tank design which is secured to the vehicle floor pan with two straps which are bolted in position. The fuel filler neck is produced from stainless steel.
The tank contains a fuel pump delivery module which collects fuel from both sides of the tank. The pump supplies the engine's fuel demands while also supplying the fuel to power the two venturi. The rapid flow of fuel through the venturi nozzle creates a depression which draws fuel back across the saddle into the pump side of the tank and fills the swirl pot.
The internal bracket incorporates the Liquid Vapor Separator (LVS) and also allows for the attachment of the LH (left-hand) fuel pick-up and the LH (left-hand) fuel level sensor. The LVS collects liquid fuel and returns it back to the tank via a Fuel Limit Vent Valve (FLVV).
To meet ORVR (on-board refueling vapor recovery) requirements, the fuel tank and associated components are designed to minimize fuel vapor loss during refueling. This is achieved by preventing fuel vapor from the fuel tank venting directly to the atmosphere. Instead fuel vapor is directed into the EVAP (evaporative emission) canister where it is stored before being purged at intervals to the engine's intake manifold. For additional information, refer to Evaporative Emissions Locations

FUEL PUMP DELIVERY MODULE









The fuel pump delivery module is located inside the fuel tank and comprises three main components; a fuel pump, a remote fuel pick-up and a top flange assembly.

Fuel Pump
The fuel pump is a rotary vane type pump, which operates in the fuel delivery module located in the RH (right-hand) side of the tank. A venturi transfer pump is also located in the RH (right-hand) side of the tank. The fuel pump module is secured in the tank with a bayonet style locking ring that is welded into the tank structure. The fuel pump module has an integral top plate for external pipe connections and also an electrical connector.
The electric pump is located in a plastic swirl pot which collects fuel from the bottom of the fuel tank via a filter. The swirl pot retains fuel and ensures that fuel is always available for the pump to draw from.
The fuel level sensor for the RH (right-hand) side of the tank is attached to the outside of the swirl pot.
The fuel delivery module is a serviceable component and is accessed via the top flange.

Remote Fuel Pick-Up and Level Sensor Assembly
The remote fuel pick-up is located in the LH (left-hand) side of the fuel tank. The pick-up arm assembly is attached to the tank internal bracket which holds the pick-up at the bottom of the tank.
The fuel pump system incorporates two jet pumps. One jet pump is integrated into the fuel pump and draws fuel from the RH (right-hand) side of the tank into the swirl pot. The other jet pump is located on the fuel delivery module on the RH (right-hand) side of the tank. A pick-up pipe located in the LH (left-hand) side of the tank allows fuel to be drawn over from the LH (left-hand) side of the tank, delivering fuel into the swirl pot. The jet pumps operate on a venturi effect created by the fuel passing through the jet pump.
The fuel level sensor for the LH (left-hand) side of the tank is attached to the pick-up arm assembly, which is secured to an internal bracket. The fuel pick-up and level sensor are serviceable components and access is by removal of the top flange on the RH (right-hand) side of the fuel tank.

Top Flange Assembly
The top flange is located on the top RH (right-hand) side of the fuel tank. The flange assembly is sealed in the tank with a sealing ring. A locking ring secures the flange assembly in the tank and requires a special tool for removal.
The outer surface of the top flange has four outlets with quick-fit connections and an electrical connector. One connection is the pressure outlet to the HP fuel pump mounted on the engine. The second outlet is the fuel supply to the Fuel Fired Booster Heater (FFBH) (if fitted). The third connection is for the fuel tank breather hose and the fourth connection (on ROW vehicles only) is the evaporative emission vapor outlet to the charcoal canister.
The electrical connector is located adjacent to the fuel tank breather outlet connection and provides the electrical interface to the fuel pump and the level sensors.

FUEL PUMP DRIVER MODULE (FPDM)
The FPDM (fuel pump driver module) is located in the LH (left-hand) rear of the luggage compartment. The module is attached to a bracket suspension turret and secured with two bolts.
The operation of the fuel pump is regulated by the FPDM (fuel pump driver module) which is controlled by the ECM (engine control module). The FPDM (fuel pump driver module) regulates the flow and pressure supplied by controlling the operation of the fuel pump using a PWM (pulse width modulation) output.
The FPDM (fuel pump driver module) is powered by a fused supply from the fuel pump relay in the BJB (battery junction box). The fuel pump relay is energized when the driver's door is opened or power mode 9 engine crank is initiated using the stop/start button. The FPDM (fuel pump driver module) supplies power to the fuel pump and adjusts the frequency of the PWM (pulse width modulation) power output to control the speed of the fuel pump and consequently the pressure and flow of fuel in the fuel delivery line to the HP fuel pump.
The PWM (pulse width modulation) signal from the ECM (engine control module) tells the FPDM (fuel pump driver module) the required speed for the fuel pump output. The on time of the PWM (pulse width modulation) signal represents half of the fuel pump speed, for example; if the PWM (pulse width modulation) signal on time is 50%, then the fuel pump is run at 100%.
The FPDM (fuel pump driver module) will only energize the fuel pump if it receives a valid PWM (pulse width modulation) signal, with an on time of between 4% and 50%. To switch the fuel pump off the ECM (engine control module) transmits a PWM (pulse width modulation) signal with an on time of 75%.
The output pressure from the fuel pump is controlled in line with changes of engine demand and temperature. The ECM (engine control module) monitors the input from the LP fuel sensor and adjusts the fuel pump output as required to maintain a nominal output pressure of 4.5 Bar (65.3 lbf/in2), except during engine start-up. At engine start-up the target pressure for the fuel delivery line is 6.3 Bar (91 lbf/in2).
If the SRS (supplemental restraint system) module outputs a crash signal on the high speed CAN (controller area network) bus, the ECM (engine control module) de-energizes the fuel pump relay to prevent any further fuel being pumped to the engine compartment.
If the ECM (engine control module) does not detect a pressure signal from the LP fuel sensor, it will stop the engine and will not allow an engine re-start. A DTC (diagnostic trouble code) will be recorded in the ECM (engine control module).

FUEL LEVEL SENSORS
Two fuel level sensors are used to measure the amount of fuel remaining in the LH (left-hand) and RH (right-hand) sides of the fuel tank. The LH (left-hand) level sensor is attached to the tank internal bracket and the RH (right-hand) level sensor is attached to the outside of the fuel pump swirl pot. Both sensors are connected to the vehicle wiring harness via the external electrical connector on the top flange assembly.
The electrical output signal is proportional to the amount of fuel remaining in each side of the fuel tank and the position of the float arms. The measured resistance is measured by the CJB (central junction box) which implements an anti-slosh function. This monitors the signal and updates the fuel level signal to the instrument cluster at regular intervals, preventing constant pointer movement caused by fuel movement in the tank due to cornering or braking. A low level fuel warning indicator is incorporated in the instrument cluster which illuminates when the fuel level in the tank falls below a predetermined level.

The fuel level sensor signals are converted into CAN (controller area network) bus messages by the CJB (central junction box) and are used by the instrument cluster for fuel gage and fuel warning indicator operation and are also monitored by the ECM (engine control module) to store OBD (on-board diagnostic) P codes for mis-fire detection when the fuel level is below a predetermined capacity.

FUEL FILLER PIPE AND TANK BREATHER ASSEMBLY
The fuel filler neck is positioned at the rear of the vehicle, above the RH (right-hand) rear wheel. The filler head and cap is covered by a molded plastic cover which is electrically locked when the vehicle is locked.
The filler cap is a conventional screw-in type which is secured to the vehicle with a lanyard. The filler cap must be securely fitted to ensure that the tank venting system is sealed. The cap has a locking mechanism which gives an audible click when the cap is correctly tightened.
Failure to correctly secure the cap will result in vapor being lost from the system to atmosphere. On North American Specification (NAS) vehicles, if the cap is incorrectly secured when the engine management system operates the Diagnostic Monitoring Tank Leakage (DMTL) system, the loss of vapor will be detected as a leak and the MIL (malfunction indicator lamp) will be illuminated.
The filler neck is a stainless steel fabrication which is secured to the vehicle body with a bracket and bolt. There is a metal stub pipe attached to the filler neck allows to which the fuel tank breather pipe is connected.
The fuel filler pipe attaches to a stub at the rear of the fuel tank which incorporates a check valve. The check valve is a spring loaded cover which acts as a one-way valve, allowing the tank to be filled but preventing fuel leaving the tank into the filler pipe.

FUEL LOW PRESSURE (LP) SENSOR
The LP fuel sensor is located on a bracket on the top of the engine. It is located in a connector between the fuel supply pipe from the fuel tank pump module and the LP supply pipe to the High Pressure (HP) fuel pump. The sensor measures the fuel pressure being supplied from the tank mounted fuel pump module to the HP fuel pump.
For additional information, refer to Electronic Engine Controls