2002 LAND ROVER DISCOVERY fuel filter

FUEL DELIVERY SYSTEM - TD5
DESCRIPTION AND OPERATION 19-1-5
The fuel pump is a 'self priming', wet type, two stage pump which is immersed in fuel in the tank and operates at all
times when the ignition switch is in position II. If the engine is not started, the ECU will 'time-out' after three minutes
and de-energise the fuel pump relay. The pump receives a feed from the battery via fuse 10 in the engine
compartment fusebox and the fuel pump relay. The relay is energised by the ECM when the ignition switch is moved
to position II.
The fuel pump assembly is retained with a locking ring and sealed with a rubber seal. The locking ring requires a
special tool for removal and refitment. An access panel for the fuel pump is located in the loadspace floor below the
carpet. The access panel is sealed to the floor with a rubber seal and retained by six self-tapping screws. A four pin
electrical connector is located on the top cover and provides power feed and earth for the fuel pump and also inputs
and outputs for the fuel gauge sender operation.
The fuel gauge sender is integral with the fuel pump. The sender is submerged in the fuel and is operated by a float
which moves with the fuel level in the tank.
Fuel pump
The fuel pump assembly comprises a top cover which locates the electrical connector, fuel burning heater connection
and four fuel pipe couplings. The top cover is attached to a plastic cup shaped housing and retained on three sliding
clips. Two coil springs are located between the cover and the housing and ensure that the fuel pump remains seated
positively at the bottom of the tank when installed.
The housing locates the two stage fuel pump and also the fuel gauge sender unit. The lower part of the housing is the
swirl pot which maintains a constant level of fuel at the fuel pick-up. A coarse filter is located in the base of the housing
and prevents the ingress of contaminants into the pump and the fuel system from the fuel being drawn into the pump.
A fine filter is located in the intake to the low pressure stage to protect the pump from contaminants. Flexible pipes
connect the couplings on the top cover to the pump.
A non-return valve is located in the base of the housing. When the fuel tank is full, fuel pressure keeps the valve lifted
from its seat allowing fuel to flow into the swirl pot. As the tank level reduces, the fuel pressure in the tank reduces
causing the valve to close. When the valve is closed fuel is retained in the swirl pot, ensuring that the swirl pot remains
full and maintains a constant supply to the fuel pump.
The two stage pump comprises a high and a low pressure stage. The low pressure stage draws fuel from the swirl
pot through the filter. The low pressure stage pumps fluid at a pressure of 0.75 bar (10.9 lbf.in
2) and a flow of 30 litres/
hour (8 US Gallons/hour) to the fuel filter. A proportion of the fuel from the low pressure stage also passes, via a
restrictor, through a jet pump which keeps fuel circulating in the swirl pot. The high pressure stage draws the low
pressure fuel from the fuel filter and pressurises it to a pressure of 4.0 bar (58 lbf.in
2). The pressurised fuel is then
passed from the pump to the injectors at a flow of 180 litres/hour (47.6 US Gallons/hour). A fuel pressure regulator is
located at the rear of the engine and ensures that the delivery pressure remains at 4.0 bar (58 lbf.in
2) by controlling
the amount of fuel returning to the fuel tank.
The fuel pump has a maximum current draw of 15 Amps at 12.5 V and is protected by a 20 Amp fuse in the engine
compartment fusebox.

FUEL DELIVERY SYSTEM - TD5
19-1-6 DESCRIPTION AND OPERATION
Fuel gauge sender
The fuel gauge sender unit comprises a rotary potentiometer operated by a float. The float rises and falls with the fuel
level in the tank and moves the potentiometer accordingly.
A voltage of 5 V is supplied to the potentiometer from the instrument pack. The output voltage from the potentiometer
varies according to the resistance through the potentiometer in relation to the fuel level. The output voltage is
connected to the fuel gauge in the instrument pack. The fuel gauge receives a battery voltage input and this is
compared with the output voltage from the rotary potentiometer. The difference between the two voltages determines
the deflection of the fuel gauge pointer.
Fuel pressure regulator and housing
A = Pre EU3 models
1Gasket
2Housing
3Bolt 3 off
4Fuel feed union and pipe
5Fuel return union and hose
6Fuel temperature sensor
7Bonded seal
8'O' ring9Circlip
10Fuel pressure regulator (EU3 models)
11'O' ring
12'O' ring
13Gauze filter
14Injector spill return pipe
15Fuel pressure regulator (pre EU3 models)
Fuel gauge reading Tank volume litres * Sender unit resistance
ohms Ω
FULL 95 15
3/4 71 36
1/2 48 64
1/4 24 110
RESERVE (fuel light ON) 11 158
EMPTY 0 245
* Tank volumes are approximate

FUEL DELIVERY SYSTEM - TD5
DESCRIPTION AND OPERATION 19-1-7
The fuel pressure regulator is located in a cast alloy housing which is attached to the rear right hand corner of the
cylinder head with three flanged bolts and sealed with a metal gasket. On pre EU3 models there are two ports in the
housing that connect with ports in the cylinder head for fuel pressure feed and return. On EU3 models there is a port
in the housing that connects with a port in the cylinder head for fuel pressure feed and a single external port for fuel
return. A gauze filter is located in the pressure feed port in the cylinder head and filters the fuel before it reaches the
injectors. The filter is a fit for life item but can be changed if required. An 'O' ring is located in a recess in the cylinder
head and provides additional sealing for the pressure feed port between the gauze filter, the cylinder head and the
housing.
A union and pipe is attached to the feed port in the housing and connects with a quick release coupling to the fuel
pressure feed pipe from the fuel pump. A second union and hose is located in the return port and provides the fuel
return connection to the fuel cooler. A third port provides location for the fuel temperature sensor which is sealed to
the housing with a bonded seal. The fuel temperature sensor is used by the Engine Control Module (ECM) for engine
management.
The fuel pressure regulator is located in a machined port in the lower part of the housing. The regulator is sealed in
the housing with two 'O' rings and secured with an internal circlip.
The regulator maintains the fuel pump delivery pressure at 4 bar (58 lbf.in
2). When the fuel pressure exceeds 4 bar
(58 lbf.in2), the regulator opens and allows fuel to return to the fuel tank via the fuel cooler. The fuel returned from the
regulator is directed back into the fuel filter before being drawn by the high pressure stage of the fuel pump and
directed back to the injectors. A special tool can be attached to the regulator housing fuel feed port and allows for the
fitment of a suitable gauge to measure fuel pump delivery pressure.
Injectors
1Solenoid housing
2Electrical connector
3Push rod socket
4Push rod return spring
5Housing
6Fuel delivery port7Fuel return port
8Nozzle cap nut
9Copper washer
10Nozzle
11'O' ring
12Cap screw 2 off

FUEL DELIVERY SYSTEM - TD5
DESCRIPTION AND OPERATION 19-1-9
Fuel filter
1Filter body
2Nut 2 off
3Bolt 2 off
4Rubber washer
5Water sensor6Filter element
7Air bleed valve
8Air bleed connection
9Copper washer 4 off
10Connector 3 off
The fuel filter is located at the rear of the vehicle, to the right of the fuel tank and is attached by a bracket with two
bolts and nuts to the right hand chassis longitudinal.
The filter has four quick release coupling connections; low pressure feed from the fuel pump, low pressure return to
the fuel pump, return line from the fuel pressure regulator and a bleed line to the fuel pump. The fuel filter removes
particulate matter from the fuel and also separates water which accumulates at the bottom of the filter.
An air bleed valve is located in the bleed line connection. The valve comprises a restrictor and a membrane. The
restrictor has a small hole in its centre. This allows air and fuel to pass through the membrane. Air can pass through
the membrane, but once the membrane is wet with fuel it will not allow further fuel to pass through.
The fuel filter has a replaceable screw-on canister type filter element which is sealed to the filter body with rubber
seals. The lower part of the canister has a screw connection for a water sensor. The filter has a flow rate of 180 litres/
hour (47.6 US Gallons/hour).

FUEL DELIVERY SYSTEM - TD5
19-1-10 DESCRIPTION AND OPERATION
Water sensor
The water sensor has a three pin electrical connector. When the sensor detects water in the filter it illuminates a
warning lamp in the instrument pack .

+ INSTRUMENTS, DESCRIPTION AND OPERATION, Description.
The water sensor attachment thread has a slot machined down one side. The filter can be purged of water by partially
unscrewing the sensor which aligns the slot in the threads with a corresponding hole in the sensor. When aligned,
water and fuel can flow down the slot and flows from a small cast tube on the side of the sensor. Re-tightening the
sensor misaligns the slot and stops the flow of fuel.
The water sensor receives a battery supply from the fuel pump relay in the engine compartment fusebox on one of
the electrical connector pins. The two remaining pins are connected to the instrument pack and an earth header joint.
The sensor operation uses the measurement of resistance between two electrodes submerged in the fuel and
activated by the presence of water.
When the ignition is moved to position II the warning lamp will illuminate for approximately two seconds to check
warning lamp functionality. TestBook can also illuminate the warning lamp to check its functionality.
When the filter is full with fuel and no water is present the resistance of the Diesel fuel will show a reading of 15 mA
maximum on the feed wire to the instrument pack. This current will not illuminate the water sensor warning lamp in
the instrument pack. When sufficient water surrounds both electrodes the resistance of the water will show a reading
of 130 mA maximum. This will supply sufficient voltage to the instrument pack to illuminate the warning lamp to alert
the driver to the presence of water in the fuel system.

FUEL DELIVERY SYSTEM - TD5
DESCRIPTION AND OPERATION 19-1-11
Operation
When the ignition switch is moved to position II, the fuel pump relay in the engine compartment fusebox is energised
by the ECM. Battery voltage is supplied from the fuel pump relay to the fuel pump which operates. If engine cranking
is not detected by the ECM within a three minute period, the ECM will 'time-out', de-energising the fuel pump relay.
When the ignition is turned off the ECM timer will reset.
The low pressure stage of the fuel pump draws fuel from the swirl pot and pumps it into the fuel filter. The high
pressure stage of the fuel pump draws the fuel from the fuel filter and pumps it along the fuel feed pipe to the cylinder
head.
The fuel enters the cylinder head through a connection on the fuel pressure regulator housing and supplies each
injector with pressurised fuel. The fuel pressure regulator maintains the fuel pressure at the injectors at 4 bar (58
lbf.in
2) by returning excess fuel back to the fuel filter. The returned fuel passes through the fuel cooler in the engine
compartment before it passes to the fuel filter.
When the engine is running, each injector is operated by an overhead camshaft which depresses a push rod in each
injector at a timed interval. When the cam has depressed the push rod and the push rod is returning to its extended
position, fuel is drawn from the fuel supply drilling into the injector.
When the ECM determines that injection is required, the ECM transmits an electrical pulse which energises the fast
acting solenoid, closing the spill valve on the injector and locking fuel in the injector body. As the cam begins to
depress the push rod, the fuel in the injector is rapidly pressurised. When the pressure exceeds the nozzle spring
pressure, the nozzle opens and injects fuel at very high pressure into the cylinder.
When the ECM determines that the injection period should end, the solenoid is rapidly de-energised, opening the spill
valve on the injector and allowing fuel to pass into the return circuit.
The ECM controls the injection timing by altering the time at which the solenoid is energised and the injection period
by controlling the period for which the solenoid is energised.

FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-1
FUEL DELIVERY SYST EM - V8 DESCRIPTION AND OPERAT ION
Fuel delivery system
1Fuel pressure regulator (hidden)
2Schraeder valve
3Fuel rail
4Injectors
5Engine block
6Fuel feed pipe
7Coarse filter
8Fine filter
9Fuel pump and fuel gauge sender assembly

FUEL DELIVERY SYSTEM - V8
19-2-6 DESCRIPTION AND OPERATION
The filler cap operated valve closes the vent line to the EVAP canister to prevent the customer trickle filling the tank.
Trickle filling greatly reduces the vapour space in the tank which in turn affects the tank's ability to breathe properly,
reducing engine performance and safety. When filling the tank, the removal of the filler cap closes the valve and the
vent line preventing the customer from trickle filling the tank. When the cap is installed the valve is opened by the cap
allowing vapour to vent to the EVAP canister.
The four ROV's are welded inside the top surface of the tank. Each ROV is connected internally in the tank by a tube
to the LVS. The ROV's allow fuel vapour to pass through them during normal vehicle operation. In the event of the
vehicle being overturned the valves shut-off, sealing the tank and preventing fuel from spilling from the vent line into
the LVS.
Fuel pump, regulator and fuel gauge sender
1Electrical connector
2Fuel feed pipe coupling
3Pump feed pipe
4Fuel regulator return pipe
5Fuel gauge sender unit
6Float
7Gauze filter
8Swirl pot
9Pump electrical connections10Pump
11Spring 2 off
12OBD pressure sensor (NAS vehicles with
vacuum type EVAP system leak detection
capability only)
13Fuel pressure regulator
14'O' ring
15'O' ring