1999 LAND ROVER DISCOVERY fuel cap

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Page 308 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-9
Pin out details connector C0634
Connector 2 (C0635): This connector contains 24 pins and is primarily used for Heated Oxygen Sensors (HO

Page 311 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual ENGINE MANAGEMENT SYSTEM - V8
18-2-12 DESCRIPTION AND OPERATION
Connector 4 (C0637): This connector contains 40 pins and facilitates use of TestBook via the Diagnostic connector.
Also contained in th

Page 351 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual ENGINE MANAGEMENT SYSTEM - V8
18-2-52 DESCRIPTION AND OPERATION
Evaporative emission control
Due to increasing legislation, all new vehicles must be able to limit evaporative emissions (fuel vapour) f

ENGINE MANAGEMENT SYSTEM - V8
18-2-52 DESCRIPTION AND OPERATION
Evaporative emission control
Due to increasing legislation, all new vehicles must be able to limit evaporative emissions (fuel vapour) from the fuel
tank.
The ECM controls the emission control system using the following components:
lEVAP canister.
lPurge valve.
lCanister vent solenoid (CVS) valve – (NAS vehicles with vacuum type EVAP system leak detection capability
only)
lFuel tank pressure sensor – (NAS vehicles with vacuum type EVAP system leak detection capability only)
lFuel leak detection pump – (NAS vehicles with positive pressure type EVAP system leak detection capability
only)
lInterconnecting pipe work.
Refer to Emissions section for operating conditions of evaporative emission systems.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Evaporative Emission Control
Operation.
On-Board Diagnostics (OBD) - North American Specification vehicles only
The ECM monitors performance of the engine for misfires, catalyst efficiency, exhaust leaks and evaporative control
loss. If a fault occurs, the ECM stores the relevant fault code and warns the driver of component failure by illuminating
the Malfunction Indicator Light in the instrument pack.
On vehicles fitted with automatic gearbox, the ECM combines with the Electronic Automatic Transmission (EAT) ECU
to provide the OBD strategy.
Conditions
If the OBD function of the ECM flags a fault during its operation, it falls into one of the following categories:
lmin = minimum value of the signal exceeded.
lmax = maximum value of the signal exceeded.
lsignal = signal not present.
lplaus = an implausible condition has been diagnosed.
Function
All of the ECM's internal diagnostic fault paths are monitored by the OBD system. Specific faults have their own
numeric code relating to certain sensors or actuators etc. These specific faults fall into two types, error codes (E xxx)
or cycle codes (Z xxx). E codes represent instantaneous faults and Z codes relate to codes generated after completion
of a drive cycle.
If an emission relevant fault occurs on a drive cycle, the ECM stores a temporary fault code, if the fault does not occur
on subsequent drive cycles the fault code stays as a temporary fault code. If the fault recurs on subsequent drive
cycles the ECM stores the fault code as a permanent code, and depending on which component has failed the ECM
will illuminate the MIL.
Immobilisation system
The ECM and the body control unit (BCU) security system comprise the immobilisation system.
The ECM and the BCU combine to prevent the engine from running unless the appropriate security criteria are met.
The ECM and the BCU are a matched pair, if either one is replaced for any reason, the system will not operate unless
the replaced unit is correctly matched to its original specification. TestBook must be used to reconfigure the
immobilisation system.
Conditions
The ECM operates immobilisation in three states:
l'New'.
l'Secure'.
l'No Code'.

Page 392 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual ENGINE MANAGEMENT SYSTEM - V8
REPAIRS 18-2-93
6.Remove 4 bolts securing fuel rail to inlet
manifold.
7.Release injectors from inlet manifold and
remove fuel rail and injectors.
8.Release spring

Page 399 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual FUEL DELIVERY SYSTEM - V8
19-2-2 DESCRIPTION AND OPERATION
Fuel tank and breather components (all
except NAS)
1Fuel filler cap
2Relief valve
3Vent to EVAP canister
4Tank breather connection
5Fuel pum

Page 400 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-3
Fuel tank and breather components
(NAS)
1Fuel filler cap
2Filler tube
3OBD pressure sensor atmospheric pipe
4Vent pipe to EVAP canister
5Fue

Page 401 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual FUEL DELIVERY SYSTEM - V8
19-2-4 DESCRIPTION AND OPERATION
Description
General
The fuel delivery system comprises a fuel tank, fuel pump and regulator and eight injectors. The system is controlled
by

FUEL DELIVERY SYSTEM - V8
19-2-4 DESCRIPTION AND OPERATION
Description
General
The fuel delivery system comprises a fuel tank, fuel pump and regulator and eight injectors. The system is controlled
by the Engine Control Module (ECM) which energises the fuel pump relay and controls the operation and timing of
each injector solenoid.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
The multiport fuel injection system is a returnless system with the fuel pressure maintained at a constant level by a
fuel pressure regulator. The regulator is located in the fuel pump housing and returns excess fuel directly from the
pump to the tank.
An electrically operated fuel pump is located in the top of the fuel tank and supplies fuel at pressure to two fuel rails
via a flexible hose. The hose is attached to the feed pipe on the fuel rail at the rear of the engine and the fuel pump
with sealed quick release couplings.
A moulded fuel tank is located at the rear underside of the vehicle between the chassis longitudinals. The tank
provides the attachment for the fuel pump and fuel gauge sender unit which is located inside the tank. The fuel system
is pressurised permanently with pressurised fuel vapour venting to an EVAP canister.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Emission Control Systems.
Fuel tank and breather
The fuel tank and breather system is a major part of the fuel delivery system. The fuel tank and breathers are located
at the rear of the vehicle between the chassis longitudinals.
Fuel tank
The moulded fuel tank is made from High Molecular Weight (HMW) High Density Polyethylene (HDPE). Continuous
layers of nylon additive are used during the moulding process. The nylon layers give an improved limit of fuel
permeation through the tank wall and are also resistant to alcohol based fuels used in the NAS market.
The tank is retained in position by a metal cradle which is secured to the chassis with two nut plates and bolts at the
rear and a stud plate and two nuts at the front. A strap above the tank is bolted to the chassis and restrains the tank
from moving upwards. The fuel tank has a useable capacity of approximately 95 litres (25 US Gallons).
An aperture in the top surface of the tank allows for the fitment of the fuel pump, regulator and fuel gauge sender unit
which is retained with a locking ring.
A reflective metallic covering is attached to the tank with two scrivets to shield the tank from heat generated by the
exhaust system.
The fuel filler is located in the right hand rear quarter panel, behind an access flap. The flap is opened electrically
using a switch on the fascia.
The filler is closed by a threaded plastic cap which screws into the filler neck. The cap has a ratchet mechanism to
prevent over tightening and seals against the filler neck to prevent the escape of fuel vapour. The filler cap has a valve
which relieves fuel pressure to atmosphere at approximately 0.12 to 0.13 bar (1.8 to 2.0 lbf.in
2) and opens in the
opposite direction at approximately 0.04 bar (0.7 lbf.in2) vacuum.
All markets except NAS: A moulded filler tube, made from HMW HDPE with no additional additives, connects the
filler to the tank via a flexible rubber hose. The filler tube is connected at its top end behind the filler flap.
NAS markets: A fabricated filler tube, made from stainless steel, connects the filler to the tank via a flexible rubber
hose. The filler tube is connected at it's top end behind the filler flap.
On all vehicles that use unleaded fuel, the filler neck is fitted with an inhibitor. The inhibitor is a tapered nozzle in the
mouth of the filler neck which will only allow the use of a standard unleaded fuel filler gun. A spring loaded flap valve
prevents the incorrect fuel from being trickle filled from an incorrect filler gun.

Page 402 of 1529

LAND ROVER DISCOVERY 1999 Workshop Manual FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-5
Fuel tank breather system (all markets except NAS)
The filler tube incorporates a tank vent which allows air and fuel vapour displaced from t

FUEL DELIVERY SYSTEM - V8
DESCRIPTION AND OPERATION 19-2-5
Fuel tank breather system (all markets except NAS)
The filler tube incorporates a tank vent which allows air and fuel vapour displaced from the tank when filling to vent to
atmosphere via the filler neck. A relief valve in the vent line to the EVAP canister prevents vapour escaping through
the canister during filling. This prevents the customer overfilling the tank and maintains the correct fuel cut-off level.
The filler tube also incorporates an integral Liquid Vapour Separator (LVS). During normal driving excess fuel vapour
is passed via the vent line into the EVAP canister. To prevent the canister from being overloaded with fuel vapour,
especially in hot climates, the vapour is given the opportunity to condense in the LVS. Fuel which condenses in the
LVS flows back into the tank through the ROV's.
A breather spout within the tank controls the tank 'full' height. When fuel covers the spout it prevents fuel vapour and
air from escaping from the tank. This causes the fuel to 'back-up' in the filler tube and shuts off the filler gun. The
position of the spout ensures that when the filler gun shuts off, a vapour space of approximately 10% of the tanks total
capacity remains. This vapour space ensures that Roll Over Valves (ROV's) are always above the fuel level and the
vapour can escape and allow the tank to breathe.
The pressure relief valve fitted in the vent line to the EVAP canister prevents 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 pressures created are too low to open the pressure
relief valve, preventing the customer from trickle filling the tank. Vapour pressures created during driving are higher
and will open the valve allowing vapour to vent to the EVAP canister.
Four ROV's are welded onto the top surface of the tank. Each ROV is connected by a tube to the main vent line to
the EVAP canister. 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.
Fuel tank breather system (NAS)
The filler tube incorporates a tank vent which allows air and fuel vapour displaced from the tank when filling to vent to
atmosphere via the filler neck. A filler cap operated valve within the fuel filler neck prevents vapour escaping through
the EVAP canister during filling. This prevents the customer overfilling the tank and maintains the correct fuel cut-off
level.
The filler tube also has an 'L' shaped, stainless steel Liquid Vapour Separator (LVS). During normal driving excess
fuel vapour is passed via the vent line into the EVAP canister. To prevent the canister from being overloaded with fuel
vapour, especially in hot climates, the vapour is given the opportunity to condense in the LVS. Fuel which condenses
in the LVS flows back into the tank via the LVS vent line and through the Roll Over Valves (ROV's).
For NAS vehicles with vacuum type EVAP system leak detection capability, a small tube is located alongside the filler
tube and terminates near to the filler neck. The tube is connected to the On Board Diagnostics (OBD) pressure sensor
in the fuel pump and provides the sensor with a reading of atmospheric pressure to compare against the tank
pressure.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Emission Control Systems.
A breather spout within the tank controls the tank 'full' height. When fuel covers the spout it prevents fuel vapour and
air from escaping from the tank. This causes the fuel to 'back-up' in the filler tube and shuts off the filler gun. The
position of the spout ensures that when the filler gun shuts off, a vapour space of approximately 10% of the tanks total
capacity remains. This vapour space ensures that the ROV's are always above the fuel level and the vapour can
escape to the LVS and allow the tank to breathe.
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.

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