Description

Fuel Tank and Lines

NOTE:
A = Hardwired









OPERATION
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.
Fuel level is biased towards the RH (right-hand) compartment in the fuel tank by drawing fuel through the internal cross over pipe via the jet pump, which serves to deliver a constant supply of fuel to the transfer pump and swirl pot assembly. High pressure fuel from the fuel pump is directed through the jet pump's orifice, creating a low pressure area to be formed in the cross over pipe. The fuel is drawn into this low pressure area in the cross over pipe and directed into the swirl pot delivery pipes.
Fuel is pumped from the fuel pump to the fuel rail via the integral filter and pressure relief valve.
The pressure relief valve assists engine starting by retaining a pre-set fuel pressure in the supply pipe and fuel rail. The pressure relief valve also limits fuel rail pressure due to temporary vapor increase in hot conditions and pressure caused by sudden load changes, for example, a fully open to closed throttle transition.
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) charcoal canister where it is stored before being purged at intervals to the engine's intake manifold.
North American Specification (NAS) vehicles feature additional connections and pipes at the rear of the filler head and also incorporates a Diagnostic Monitoring Tank Leakage (DMTL) pump for leak detection requirements.

Fuel System Schematic Diagram









FUEL TANK

NOTE:
NAS fuel system shown









The fuel tank is a saddle type tank, blow moulded from HDPE (high density polyethylene). The tank is located forward of the rear suspension and is mounted using two metal straps. The tank is a sealed unit with the only internal access being through the fuel pump module aperture on the top of the tank.
The fuel pump module flange has a six pin external connector which provides the electrical connections for the fuel pump and both fuel level sensors. A quick release connector provides for the connection of the fuel feed pipe.
The flange is fitted with a locking ring and seal. The seal locates in a groove on the tank. The locking ring locates and clamps on the encapsulated ring that is moulded into the fuel tank. The flange has a tag which locates in the top of the tank to ensure correct orientation.
A carrier within the tank provides for the mounting of the passive side jet pump tube, vent valve, ROV and liquid vapor separator (LVS), level sensors and passive side drain.

FUEL PUMP MODULE









The fuel pump is a variable speed rotary vane type. The pump is energized by the fuel pump relay which is located in the RJB (rear junction box) and the FPDM (fuel pump driver module) which is located under the RH (right-hand) floor pan above the rear suspension stabilizer bar. The relay and FPDM (fuel pump driver module) are controlled by the ECM (engine control module).
A fine mesh filter is located in the lower section of the pump module. This provides filtration to the fuel as it is drawn into the module. There is a winged filter on the fuel pump that gives additional protection and a life time fuel filter integrated into the flange which eliminates the need for an additional filter further downstream in the fuel system.
The RH (right-hand) fuel level sensor is mounted into the pump module housing.

FUEL PUMP DRIVER MODULE (FPDM)





The FPDM (fuel pump driver module) is located on a bracket which is integral with the charcoal canister. The module is attached to one end of the canister with a bracket.
The fuel pump operation is regulated by a 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 RJB (rear junction box). The fuel pump relay is energized on opening the driver's door, pressing the start button only or pressing the start button and the footbrake (which initiates engine cranking). 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), 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 Jaguar diagnostic system. The FPDM (fuel pump driver module) itself cannot be interrogated by the approved Jaguar diagnostic system.

FUEL LEVEL SENSORS









Two fuel level sensors are installed in either side of the saddle tank. One is mounted on the fuel pump module, the other is mounted on the carrier in the LH (left-hand) side of the fuel tank. The sensors are a float operated MAPPS (magnetic passive position sensor) which provide a variable resistance to ground for the output from the fuel gauge. The sensor is sealed from the fuel preventing contamination of the contacts, increasing reliability. The fuel level sensors are connected to the external electrical connector on the flange via the connector 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.









The film resistors are arranged in a linear arc with resistance ranging from 51.2 to 992.11 Ohms. The electrical output signal is proportional to the amount of fuel in the tank and the position of the float arm. 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 lamp is incorporated in the instrument cluster and illuminates when the fuel level is low.
The fuel level sender signal is converted into a CAN (controller area network) 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) message to store additional OBD (on-board diagnostic) 'P' Codes for misfire detection when the fuel level is below a predetermined capacity.

JET PUMP
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.

FUEL VENT VALVE
The fuel level vent valve is located in the upper half of the tank and is connected into a separator which is connected to the Roll Over Valve (ROV) tank breather. The main purpose of the fuel level vent valve is to control the fill volume of the tank. During filling, air trapped inside the tank and a small amount of vapor is passed via the fuel level vent valve to the tank breather. The air and vapor mix then vents to atmosphere through the breather. During filling, when the tank reaches its full level, the fuel level vent valve closes and prevents air/vapor passing through to the tank breather. The resulting back pressure causes refueling to stop automatically.
The fuel level vent valve is always open when the fuel tank is below full, providing an unrestricted air/vapor outlet to the tank breather.

FUEL FILLER PIPE

Fuel Filler Pipe (ROW)









Fuel Filler Pipe (NAS)









The fuel filler head is positioned at the rear of the vehicle, above the right hand rear wheel. The filler head 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 head is stainless steel fabrication which is secured to the vehicle body with 2 brackets and a location lug on the filler bowl. The formed pipe locates in a short flexible hose attached to the tank which is secured with worm drive clamps at each end.

FUEL 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.