1999 LAND ROVER DISCOVERY fuel cap

FUEL DELIVERY SYSTEM - V8
19-2-6 DESCRIPTION AND OPERATION
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
The fuel pump is a 'self priming' wet type pump which is immersed in fuel in the tank. The fuel pump operates at all
times when the ignition switch is in position II. If the engine is not started, the ECU will 'time-out' after 2 seconds and
de-energise the fuel pump relay to protect the pump. 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 is retained with a locking ring and sealed with a rubber seal. The locking ring requires a special tool
for removal and fitment. An access panel for the fuel pump is located in the loadspace floor below the loadspace
carpet. The access panel is sealed to the floor with a rubber seal and retained by six self-tapping screws.
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 DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-7
Fuel pump
The fuel pump assembly comprises a top cover which locates the fuel pressure regulator, electrical connector and
fuel pipe coupling. The top cover is attached to a plastic cup shaped housing by two metal springs. The housing
locates the pump and the fuel gauge sender unit.
The lower part of the housing is the swirl pot, which maintains a constant fuel level at the fuel pick-up. A feed pipe
from the pump to the coupling connection and a return pipe from the regulator connect between the top cover and the
housing.
A coarse filter is attached to the base of the housing and prevents the ingress of large contaminants into the swirl pot.
A gauze filter prevents particles entering the fuel pump.
Surrounding the pump is a large fine paper filter element which further protects the fuel pressure regulator, engine
and injectors from particulate contamination. The paper filter is not a serviceable item and removes the requirement
for an external in-line filter.
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.
A four pin electrical connector is located on the top cover of the pump and provides power feed and return for fuel
pump and fuel gauge rotary potentiometer operation. A single quick release coupling connects the fuel feed pipe to
the outer top surface of the pump.
Two metal springs are attached to the top cover and the housing of the pump. When the pump is installed it seats on
the lower surface inside the tank. The springs exert a downward pressure on the pump and ensure that the pump is
located positively at the bottom of the fuel tank.
The fuel pump has a maximum current draw of 6.5 A at 12.5 V.
On NAS vehicles with vacuum type EVAP system leak detection capability only, the fuel pump top cover is fitted with
an On Board Diagnostics (OBD) pressure sensor. This sensor has a three pin electrical connector which provides a
connection between the sensor and the ECM. The sensor is sealed in the top cover with an 'O' ring and secured with
a clip. The sensor monitors tank pressure during OBD tests of the fuel evaporation system integrity. A hose is
connected to the sensor and is routed across the top of the fuel tank and terminates at the top of the fuel filler tube.
The pipe is open to atmosphere and provides atmospheric pressure for the sensor operation.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Fuel pressure regulator
The fuel pressure regulator is located in the underside of the top cover. The regulator is sealed with two 'O' rings and
retained with a clip.
The regulator is connected to the fuel feed pipe at the top of the pump housing and maintains the fuel pump delivery
pressure to 3.5 bar (50 lbf.in
2). When the fuel delivery pressure exceeds 3.5 bar (50 lbf.in2), the regulator opens and
relieves excess pressure back to the swirl pot via a return pipe. The regulator ensures that the fuel rails and injectors
are supplied with a constant pressure.
The fuel pump delivery pressure and pressure regulator operating pressure can be checked using a Schraeder type
valve located at the rear of the engine on the fuel rail. The valve allows the pump delivery pressure to be measured
using a suitable gauge and an adaptor and hose which are special tools.

FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-9
Injectors
1'O' ring 2 off
2Electrical connector
3Steel housing
4Filter strainer
5Spring6Valve needle and armature
7Valve seat/spray orifice
8Plastic housing
9Solenoid winding
An injector for each cylinder is mounted externally in the lower inlet manifold on the engine. The injector protrudes
into the inlet manifold tract, where it releases a controlled delivery of fuel into the manifold air inlet.
Each injector is sealed to the fuel rail and the inlet manifold with 'O' rings. Spring clips retain each injector to the fuel
rail and the attachment of the fuel rail clamps the injectors in the lower manifold.
The injector housing is manufactured from plastic which encapsulates a high-alloy steel housing. The steel housing
contains all components which come into contact with fuel. The plastic housing also provides the attachment for the
engine harness connector for the injector. A solenoid is located between the two housings and moves a valve needle
via an armature. The valve needle seats on a valve seat which incorporates a spray orifice plate. A filter strainer is
fitted at the connection with the fuel rail to remove any particulate matter from the fuel before it enters the injector.
When the ECM energises the solenoid, the armature moves lifting the valve needle off its seat. This allows
pressurised fuel from the fuel rail to pass through the injector housing and needle to the spray orifice. The spray orifice
controls the spray shape and fuel metering. When the solenoid is de-energised, the valve needle returns to the valve
seat, aided by a spring, closing off the injection of fuel into the inlet.
Each injector receives a battery supply voltage via a fuse in the engine compartment fusebox. The fuel delivery timing
is controlled by the ECM, which, at a precisely timed interval, provides a ground path for the injector. The completion
of the ground path operates the injector to allow fuel at pump pressure to be delivered from the fuel rail to the injector
nozzle. Each injector sprays a finely atomized spray of fuel into the inlet, where it is mixed with the intake air prior to
combustion.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
Faults for each injector are stored in the ECM and can be retrieved using TestBook. Each injector can be checked
across the two connector pins. For a correctly functioning injector a resistance of between 13.8 and 15.2 ohms at a
temperature of 20°C (65°F) should be read across the pins.

FUEL DELIVERY SYSTEM - V8
19-2-16 REPAIRS
Filler tube - fuel
$% 19.55.07
Remove
1.Raise rear of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
2.Ensure fuel tank is less than half full. If not,
drain fuel tank to less than half full.

+ FUEL DELIVERY SYSTEM - V8,
ADJUSTMENTS, Fuel tank - drain.
3.Remove filler cap.
Non NAS installation
4.Drill out rivet securing lower part of mud flap
support bracket and release bracket .
5. All except NAS models: Position suitable
container beneath filler tube and disconnect
filler hose, breather hose and vent pipe from
filler tube.
WARNING: TAKE ALL NECESSARY
PRECAUTIONS AGAINST FIRE AND
EXPLOSION.
NAS installation6. NAS models: Position suitable container
beneath filler tube to tank connection , loosen
securing clip and release filler tube from fuel
tank.
WARNING: TAKE ALL NECESSARY
PRECAUTIONS AGAINST FIRE AND
EXPLOSION.
7. NAS models: Disconnect vent pipes from filler
tube.
8. Release filler tube from grommet in body and
remove from under rear wing. Collect grommet.
9. NAS models: Remove cable tie securing
pressure sensor pipe to filler tube and remove
filler tube.
Refit
1. NAS models: Position filler tube to pressure
sensor pipe and secure with new cable tie.
2. Fit grommet to body, position filler tube under
rear wing and secure in grommet.
3. NAS models: Connect filler tube to fuel tank
and secure with clip. Connect vent pipes to filler
tube.
4. All except NAS models: Connect filler hose
and breather hose to filler tube and secure with
clips. Connect vent pipe to filler tube.
5. Position support bracket to mud flap and
secure with new rivet.
6.If applicable, refill fuel tank with extracted fuel.
7.Fit filler cap.
8.Remove stand(s) and lower vehicle.

MANIFOLDS AND EXHAUST SYSTEMS - V8
30-2-6 DESCRIPTION AND OPERATION
Exhaust manifolds
Two handed, cast iron exhaust manifolds are used on the V8 engine. Each manifold has four ports which merge into
one flanged outlet positioned centrally on the manifold.
Each manifold is attached to its cylinder head with eight Torx bolts. Each bolt is fitted with a 'cotton reel' shaped spacer
which allows for a longer bolt resulting in increased torque loading on each bolt. Two laminated metal gaskets seal
each manifold to its cylinder head. The flanged outlet on each manifold provides the attachment for the front pipe of
the exhaust system.
Exhaust system
The exhaust system comprises a front pipe assembly with two front pipes each incorporating a catalytic converter, an
intermediate pipe incorporating a silencer and a tail pipe assembly which also has a silencer. The exhaust system is
constructed mainly of 63 mm (2.48 in) diameter extruded pipe with a 1.5 mm (0.06 in) wall thickness. All pipes are
aluminized to resist corrosion and the silencers are fabricated from stainless steel sheet.
Front pipe assembly
The front pipe assembly is of welded and fabricated construction. A front pipe from each exhaust manifold merges
into one flanged connection. Two captive studs on the flange provide attachment to the intermediate pipe with
locknuts. Each front pipe has a welded flange which is attached to each manifold and secured with three studs and
flanged nuts and sealed with a metal laminated gasket. The gasket comprises a heat resistant fibre between two thin
metallic layers to enhance the sealing properties of the gasket.
A catalytic converter is located in each front pipe. The catalytic converters are different shapes to allow clearance
between the body and transmission. Both catalytic converters are of similar internal construction.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Emission Control Systems.
CAUTION: Ensure the exhaust system is free from leaks. Exhaust gas leaks upstream of the catalytic
converter could cause internal damage to the catalytic converter.
From the catalytic converters, the front pipes merge into one pipe which terminates at a flanged joint. The flange
connects with the intermediate pipe, sealed with an olive and secured with studs and locknuts.
Intermediate pipe and silencer
The intermediate pipe is of welded and fabricated tubular construction. It connects at its forward end with a flange on
the front pipe assembly and is secured with locknuts to captive studs in the front pipe assembly flange. The rear
section of the intermediate pipe connects to the tail pipe assembly via a flanged joint, sealed with a metal gasket and
secured with locknuts and studs.
The forward and rear sections are joined by a silencer. The silencer is fabricated from stainless steel sheet to form
the body of the silencer. An end plate closes each end of the silencer and is attached to the body with seam joints.
Perforated baffle tubes inside the silencer are connected to the inlet and outlet pipes on each end plate. Internal baffle
plates support the baffle tubes and together with a stainless steel fibre absorb combustion noise as the exhaust gases
pass through the silencer.
The intermediate pipe is attached by two brackets, positioned at each end of the silencer, and mounting rubbers to
the chassis. The mounting rubbers allow ease of alignment and vibration absorption. The two mounting rubbers are
fitted with removable heat deflectors to prevent heat from the silencer damaging the material.
Tail pipe assembly
The tail pipe is of welded and fabricated construction. It connects to the intermediate pipe with a flanged joint secured
with studs and locknuts and sealed with a metal gasket. The pipe is shaped to locate above the rear axle allowing
clearance for axle articulation. The pipe is also curved to clear the left hand side of the fuel tank which has a reflective
shield to protect the tank from heat generated from the pipe.
A fabricated silencer is located at the rear of the tail pipe. The silencer is circular in section and is constructed from
stainless steel sheet. A baffle tube is located inside the silencer and the space around the baffle tube is packed with
a stainless steel fibre. The holes in the baffle tube allow the packing to further reduce combustion noise from the
engine. The tail pipe from the silencer is curved downwards at the rear of the vehicle and directs exhaust gases
towards the ground. The curved pipe allows the exhaust gases to be dissipated by the airflow under the vehicle and
prevents gases being drawn behind the vehicle.
The tail pipe is attached by a bracket, positioned forward of the silencer, and a mounting rubber to the chassis. The
mounting rubber allows ease of alignment and vibration absorption.

BODY CONTROL UNIT
DESCRIPTION AND OPERATION 86-3-1
BODY CONTROL UNIT DESCRIPTION AND OPERAT ION
Description
General
The Body Control Unit (BCU) is located behind the passenger glovebox and is connected to the main harness by four
connectors on its bottom edge and an additional connector located on the side of the BCU casing. Mounting the BCU
behind the fascia makes it reasonably inaccessible for intruders to disable the anti-theft system.
The BCU uses solid-state microprocessor control to perform logical operations and timing functions for a variety of
the vehicle's electrically operated systems, these include:
lDoor locking.
lAnti-theft alarm and immobilisation system.
lExterior lighting including direction indicators and hazard warning lamps.
lCourtesy lighting.
lWipers and washers.
lElectric windows and sunroof.
lHeated windows.
The BCU also communicates with several other electronically controlled systems such as the EAT ECU and SLABS
ECU and also has a datalink between the Intelligent Driver Module (IDM) and the instrument pack. The datalink is a
low speed bus capable of transmitting and receiving messages at a data rate of 10,400 bits per second. Additional
inputs and outputs to peripheral devices are included which are necessary for determining vehicle status for particular
logical operations e.g. crank, ignition key inserted, fuel flap enable etc.
The BCU receives its power supply from the engine compartment fuse box, and is protected by a 10 A fuse.
The BCU communicates with the IDM to provide the control signals to perform power switching operations in
conjunction with dedicated relays.
IDM
The IDM is integrated into the passenger compartment fuse box, which is mounted behind the fascia below the
steering column. There are no harnesses between the fuse box and the IDM. The IDM performs the power switching
operations for several of the vehicle's electrical systems.
The IDM communicates with the BCU and the instrument pack via a serial interface. If the BCU or the IDM is replaced,
the communications link between the two units has to be re-established. This can be done either by switching on the
ignition and leaving it on for five minutes, or by using TestBook. The vehicle immobilisation will remain active until the
communications link between the BCU and IDM has been re-established.
Transit mode
To prevent excessive battery drain during transit to overseas markets, the vehicle is placed in a transit mode. The
following functions are disabled when the vehicle is in transit mode:
lVolumetric sensors.
lPassive immobilisation.
lImmobilisation of the vehicle by use of door lock.
lIgnition key interlock.
lElectric seat enable time-out with driver's door open.