Fuel Tank and Lines
Fuel Tank and Lines
5.0L V8 FUEL TANK AND LINES COMPONENT LOCATION (All except NAS)
5.0L V8 FUEL TANK AND LINES COMPONENT LOCATION (NAS ONLY)
GENERAL
The major components of the 5.0L V8 fuel system comprises a fuel tank, a fuel delivery module, a fuel filler assembly and two fuel level sensors.
The 5.0L V8 fuel system uses a returnless fuel system which comprises a fuel pump mounted in the fuel tank to deliver fuel at a constant flow and pressure to the fuel rails which supply fuel to all fuel injectors.
The fuel pump operation is regulated by a FPDM (fuel pump driver module) which is controlled by the engine management system. The driver module regulates the flow and pressure supplied by controlling the operation of the fuel pump using a PWM (pulse width modulation) output.
The fuel rails and the injectors are described in Fuel Charging and Controls - 5.0L V8. For additional information, refer to Fuel Charging and Controls Fuel Charging and Controls
For additional information, refer to Fuel Charging and Controls Fuel Charging and Controls Fuel system emission control is described in Engine Emission Control - 5.0L V8 For additional information, refer to Electronic Engine Controls Description and Operation
For additional information, refer to Electronic Engine Controls Description and Operation
FUEL SYSTEM SCHEMATIC DIAGRAM
FUEL TANK
The fuel tank is constructed from moulded plastic and is mounted under the rear seat floor pan, forward of the rear suspension. The fuel tank has a capacity of 104.5 liters (27.6 US gallons). The tank is a saddle tank design with a fuel delivery module located inside the tank to collect the fuel from each side of the tank.
A vapor separator is attached to the top of the tank. The vapor separator collects liquid fuel and returns it back to the fuel tank via the LH (left-hand) roll over valve.
The fuel tank is the same tank introduced for 2006MY vehicles but with revised fuel delivery modules for 2010MY 5.0L V8 vehicles.
FUEL DELIVERY MODULE
The fuel delivery module is a new design for 5.0L V8 2010MY vehicles. The 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 variable-speed rotary-vane type, which operates in a fuel pump module located in the RH (right-hand) side of the fuel tank. A venturi transfer pump is located in the RH (right-hand) side of the tank. The fuel pump module is secured in the fuel tank with a bayonet style locking ring that is welded into the tank structure. The fuel pump module has an integral top plate for the external pipe work and electrical connectors.
The fuel pump delivers fuel at a maximum pressure of 630 kPa (6.3 bar; 91.4 lbf/in.2) to the filter bowl in the top flange.
The pump has a spring loaded top plate which secures the pump by compression in its location in the front RH (right-hand) side of the fuel tank. The electric pump is located in a plastic swirl pot which collects fuel from the base of the fuel tank via a filter.
The fuel level sensor the right hand side of the tank is attached to the outside of the swirl pot.
The fuel pump is a serviceable component and access to the pump is by removal of the top flange.
Remote Fuel Pick-Up and Level Sensor Assembly
The remote fuel pick-up is located in the front LH (left-hand) side of the fuel tank. The fuel pick-up has a spring loaded frame which secures the assembly by compression in the fuel tank.
The fuel 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 fuel tank. The other jet pump is located on the fuel delivery module on the RH (right-hand) side of the tank. There is a pipe that is located in the LH (left-hand) side of the tank that 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 at pump output pressure passing through the jet pump. This draws additional fuel from the LH (left-hand) side of the tank through ports in the jet pump body, delivering additional fuel to the swirl pot.
The fuel level sensor for the LH (left-hand) side of the fuel tank is attached to the fuel pick-up frame. The fuel pick-up and the level sensor are serviceable components and access is by removal of the flange cover on the top LH (left-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 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 flange has two outlets with quick-fit connections. One connection is the pressure outlet to the fuel rail, the second outlet is the fuel supply to the Fuel Fired Booster Heater (FFBH) pump, if fitted. For additional information, refer to Auxiliary Heater An electrical connector is located adjacent to the pipe connections and provides the electrical interface to the fuel pump and the level sensors.
On the underside of the flange, inside the tank, is a moulded housing which contains the non-serviceable fuel filter. Fuel from the fuel pump enters the base of the housing and passes through the filter before exiting the tank to the fuel rail or the FFBH pump, if fitted. An electrical connection on the base of the filter housing provides a ground for the filter.
FUEL PUMP DRIVER MODULE (FPDM)
The FPDM (fuel pump driver module) is attached to and located under a cover which is located below the RH (right-hand) side of the rear seat cushion.
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 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 supply from the fuel pump relay in the EJB (engine junction box). The fuel pump relay is energized on opening the driver's door or when power mode 9 engine crank is initiate using the stop/start button. The FPDM (fuel pump driver module) supplies power to the fuel pump, and adjusts the power to control the speed of the fuel pump and thus the pressure and flow in the fuel delivery line.
A 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. The on time of the PWM (pulse width modulation) signal represents half the fuel pump speed, e.g. if the PWM (pulse width modulation) signal has an on time of 50%, the FPDM (fuel pump driver module) drives the pump 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 will change with changes of engine demand and fuel temperature. The ECM (engine control module) monitors the input from the fuel rail LP sensor and adjusts the speed of the fuel pump as necessary to maintain a nominal output pressure of 450 kPa (4.5 bar; 65.3 lbf/in.2), except during engine start-up. At engine start-up the target pressure for the fuel delivery line is 630 kPa (6.3 bar; 91.4 lbf/in.2).
If the SRS (supplemental restraint system) 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.
If the ECM (engine control module) does not detect pressure in the fuel delivery line, it stops, or refuses to start the engine and stores the appropriate DTC (diagnostic trouble code).
The ECM (engine control module) receives a monitoring signal from the FPDM (fuel pump driver module). Any DTC (diagnostic trouble code)'s produced by the FPDM (fuel pump driver module) are stored by the ECM (engine control module).
DTC (diagnostic trouble code)'s can be retrieved from the ECM (engine control module) using an approved Land Rover diagnostic system. The FPDM (fuel pump driver module) itself cannot be interrogated by the approved Land Rover diagnostic system.
FUEL LEVEL SENSORS
Two fuel level sensors are used in the fuel tank to measure the amount of remaining fuel in the LH (left-hand) and RH (right-hand) sides of the fuel tank. The LH (left-hand) level sensor is attached to the frame of the fuel pick-up and the RH (right-hand) level sensor is attached to the fuel pump swirl pot. The sensors are connected to the vehicle wiring harness via a connector on the outer face of the top flange assembly.
The sensors are a Magnetic Passive Position Sensor (MAPPS) which provides a variable resistance to ground for the output from the fuel gauge. The sensor is sealed from the fuel preventing contamination of the contacts and increasing reliability. The front and rear fuel level sensors are connected to the external electrical connector on the flange via the connectors on the underside of the fuel pump module flange.
The sensor comprises a series of 51 film resistors mounted in an arc on a ceramic surface. The resistors are wired in series with individual contacts. A soft magnetic foil with 51 flexible contacts is mounted a small distance above the film resistors. A magnet, located below the ceramic surface, is attached to the sender unit float arm. As the float arm moves, the magnet follows the same arc as the film resistors. The magnet pulls the flexible contacts onto the opposite film resistor contacts forming an electrical circuit.
Sensor Operating Principle
The film resistors are arranged in a linear arc with resistance ranging from 51.2 to 992.11 Ohms. The electrical output signal output is proportional to the amount of fuel in each side of the tank and the position of the float arms. The measured resistance is processed by the instrument cluster to implement an anti-slosh function. This monitors the signal and updates the fuel gauge pointer position at regular intervals, preventing constant pointer movement caused by fuel movement in the tank due to cornering or braking.
A warning indicator is incorporated in the instrument cluster and illuminates when the fuel level is at or below 10 liters (2.64 US gallons).
The fuel level sender signals are converted into a CAN (controller area network) bus message by the instrument cluster as a direct interpretation of the fuel tank contents in liters. The ECM (engine control module) uses the CAN (controller area network) bus message to store additional OBD (on-board diagnostic) P Codes for misfire detection when the fuel level is below a predetermined capacity.
NOTE:
These figures are with the vehicle on level ground. Sensor readings will differ with varying vehicle inclinations.
NOTE:
These figures are with the vehicle on level ground. Sensor readings will differ with varying vehicle inclinations.
FUEL FILLER PIPE AND TANK BREATHER ASSEMBLY
Fuel Filler Pipe Assembly (All Except NAS)
Fuel Filler Pipe Assembly (NAS Only)
The fuel filler head is positioned at the rear of the vehicle, above the right hand rear wheel. The filler head and cap is covered by a moulded 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 filler cap will result in vapor being lost from the system. On 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 lamp will be illuminated.
The filler head is a stainless steel fabrication. A bracket provides for the attachment of the filler head to the vehicle body.
A connection on the rear of the filler head allows for the connection of the fuel tank breather pipe from the vapor separator on ROW vehicles and from the roll over valves on NAS vehicles.
The fuel filler pipe locates in the tank and incorporates a spitback flap in the tank end of the pipe. The flap is a spring loaded cover which acts as a 1-way valve, allowing the tank to be filled but preventing fuel leaving the tank into the filler pipe.
All vehicles have a charcoal canister breather pipe which is connected from the charcoal canister and is routed alongside the fuel filler pipe to the filler head. The filler head end of this pipe is connected differently depending on market as follows:
- On ROW vehicles the breather pipe is fitted with a mesh and allows fresh air to be drawn into the charcoal canister when fuel vapor is being purged from the system.
- On NAS vehicles the breather pipe is connected to the DMTL pump. Fresh air is drawn into the pipe via a DMTL filter integral with the pump when fuel vapor is being purged from the system. When the DMTL system is active, the breather pipe is closed by the pump, sealing the system and allowing the system to be pressure checked for leakage.
For information on the charcoal canister and purging system refer to the evaporative emissions section. For additional information, refer to Evaporative Emissions
A second pipe is routed alongside the charcoal canister breather pipe. On ROW vehicles, this pipe is the fuel tank breather pipe from the vapor separator and is connected into the fuel filler pipe near to the filler head. On NAS vehicles, this pipe is smaller in diameter and also serves as the fuel tank breather pipe. The pipe is not connected to the vapor separator but allows fuel vapor from the right hand roll over valve to vent into the connection with the fuel filler pipe near to the filler head.
A pipe is routed across the top of the tank in front of the vapor separator. This pipe connects the charcoal canister to the purge valve located in the engine compartment.
FUEL LOW PRESSURE (LP) SENSOR
The fuel LP sensor supplies a pressure signal to the ECM (engine control module) to enable closed loop control of the fuel pump. The fuel LP sensor is installed in a manifold in the fuel delivery line. The manifold is located in the rear of the front LH (left-hand) wheelarch, behind the splash shield.