1995 LAND ROVER DISCOVERY fuel

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DESCRIPTION AND OPERATION REV: 09/95 Exhaust emission control.
The fuel injection system provides accurately metered
quantities of fuel to the combustion chambers to
ensure the most efficient air to fuel ratio under all
conditions of operation. A further improvement to
combustion is made by measuring the oxygen content
of the exhaust gases to enable the quantity of fuel
injected to be varied, according to conditions, to
correct any unsatisfactory composition of the exhaust.
The main components of the exhaust emission
system are two Catalytic converters which are an
integral part of the front exhaust pipe assembly. The
Catalytic converters are included in the system to
reduce the emission, to atmosphere, of carbon
monoxide, oxides of nitrogen, and hydrocarbons. The
active constituents of the converters are platinum and
rhodium. The correct functioning of the converters is
dependent upon close control of the oxygen
concentration in the exhaust gas entering the catalyst.
The oxygen content of the exhaust gas is monitored
by the heated oxygen sensors. Information on the
heated oxygen sensors is contained in the relevant
Fuel System section,
See FUEL SYSTEM MFI,
Description and operation, or See FUEL SYSTEM
SFI, Description and operation,
The ECM can then
make an appropriate adjustment to the fuel supply to
correct the composition of the exhaust.
CAUTION: Unleaded fuel only must be
used on vehicles fitted with catalytic
converters. As a reminder,a label to
indicate this is adhered to the inside of the fuel
filler flap. Furthermore the filler neck is designed
to accommodate only unleaded fuel pump
nozzles.

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DESCRIPTION AND OPERATION REV: 09/95 Evaporative emission control system - pre
advanced EVAPS.
The system is designed to prevent harmful fuel vapour
from escaping to the atmosphere. The system
consists of a vapour separator tank, connected to the
fuel tank and located between the body inner and
outer panels on the right hand side of the vehicle near
the rear wheel arch. An adsorbtion canister,
containing activated charcoal, is positioned in the
engine compartment attached to the front right
valance. The two components are connected by a
pipe running the length of the chassis.
A Pressure relief to atmosphere.
B From fuel tank to separator.
C To adsorbtion canister.
D Pressure relief valve.
E Pressure relief valve.
F Shut-off valve.
G "Speed Fit" connectors.A pressure relief valve is fitted in the hose which is
open to atmosphere. This valve acts as a safety valve
should a build-up of pressure occur in the system, for
example if a hose became blocked or kinked. The
volume of vapour emitted, in such an instance, would
be acceptable.
A pressure relief valve is also fitted in the hose
connected to the adsorbtion canister and releases
vapor to the canister when the pressure in the
separator reaches between 5 and 7 Kpa.
In the top of the separator a shut-off valve is
incorporated in the vapor exit port to prevent the
possible presence of any liquid fuel being transmitted
to the adsorbtion canister should the vehicle roll over.
The adsorbtion canister, which is connected by a hose
to the plenum chamber, absorbs and stores the fuel
vapour from the fuel tank while the engine is not
running. When the engine is started, the vapour is
purged from the canister by air drawn through an
orifice in the base of the canister and by the influence
of vacuum at the top. The vapour drawn into the
plenum chamber through a solenoid operated purge
valve is finally burnt in the combustion chambers.
The purge valve, which is attached to the adsorbtion
canister support bracket, is controlled by the Engine
Control Module ECM which determines the most
emission acceptable time at which purging should
take place. This will normally be at engine speeds
above idle and when the vehicle is in motion. A signal
from the ECM to the purge valve operates the
solenoid and opens the valve to purge the canister of
fuel vapour.

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DESCRIPTION AND OPERATION REV: 09/95 EVAPORATIVE CONTROL SYSTEM - PRE
ADVANCED EVAPS
1. Adsorption canister and purge valve.
2. Location of vapour separator and pipes.
3. Fuel tank.

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DESCRIPTION AND OPERATION ADD: 09/95 EVAPORATIVE EMISSION CONTROL SYSTEM -
ADVANCED EVAPS
Component location
1.EVAP canister
2.EVAP canister vent solenoid (ECVS)
3.EVAP canister purge valve
4.Anti-trickle fill valve
5.Liquid/vapour separator
6.Fuel filler neck assembly
7.Fuel tank
8.Fuel pump and gauge sender unit

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DESCRIPTION AND OPERATION ADD: 09/95
Fuel filler neck components
A Anti-trickle fill valve
B Liquid/Vapour Separator
C Vent line to pressure sensor
D From fuel tank to liquid/vapour separator
E From EVAP canister to anti-trickle fill valve
F Fuel filler hose, Dual layer, convolute nylon
G Fuel tank internal breather hoseIdentification
The system was introduced on all North American
specification vehicles from October 1996 and the
vehicles can be recognised by the information
contained in theEVAP. FAMILYentry on the
underbonnet Emission label (mounted on the vertical
face of the bonnet lock platform).
A - Vehicles with advanced EVAPS
VLR1124AYPFE
B - Vehicles without advanced EVAPS
VLR1060AYPBC

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DESCRIPTION AND OPERATION ADD: 09/95 System operation
The system is designed to prevent fuel vapour
escaping to atmosphere, and consists of four roll-over
valves fitted internally in the fuel tank, connected to
the liquid/vapour separator by a nylon line. The
separator is mounted to the side of the filler neck. An
EVAP canister is positioned in the engine
compartment mounted on the right front side valance.
The liquid/vapour separator and EVAP canister are
connected by a nylon line which runs the length of the
chassis.
Pressure/vacuum relief valves are incorporated into
the fuel filler cap and are designed to protect the fuel
tank from permanent deformation in the event of
system pressure or vacuum exceeding the system
operating parameters. There are no other relief or
one-way valves in the system.
A vent line flow restrictor known as an anti-trickle fill
valve is fitted to the filler pipe in the line between the
tank and EVAP canister. The function of this valve is
to prevent overfilling the tank by trickling fuel in,
thereby preserving the vapour space in the tank to
allow for fuel expansion during hot weather.
The valve achieves this by blocking the vent line
during the fuel filling process. The valve is operated
by the action of inserting the filler gun so that when
the fuel in the tank reaches the level of the filling
breather, flow cut off occurs due to fuel filling the filler
pipe.During normal vehicle operation and when the engine
is switched off, the venting system between the fuel
tank and EVAP canister is open to allow the free
passage of vapour.
The EVAP canister, which is connected by a nylon
hose to the plenum chamber, absorbs and stores the
fuel vapour from the fuel tank when the engine is not
running. With the engine running, vapour is purged
from the EVAP canister by allowing outside air to be
drawn through the EVAP canister vent solenoid and
link pipe by the influence of manifold vacuum to the
EVAP canister purge connection on the canister.
Filter pads are fitted above and below the charcoal
and in the EVAP canister vent solenoid to prevent the
ingress of foreign matter into the purge line.
The EVAP canister purge valve, which is fitted in the
line from the EVAP canister to the plenum, is
controlled by the ECM which determines the most
emission acceptable time at which purging should
take place. This will normally be at engine speeds
above idle and when the vehicle is in motion.
The EVAP canister vent solenoid is mounted on the
side of the EVAP canister bracket and is connected to
the EVAP canister by a length of large bore hose. The
ECVS is controlled by the ECM and is normally open.
The function of the ECVS is to block the air intake
side of the EVAP canister. When the system receives
an ECM signal the valve closes; this allows the
system leak check to take place. The leak check only
occurs when pre-determined vehicle operating
conditions are met.

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FAULT DIAGNOSIS REV: 09/95 TESTING EVAPORATIVE EMISSION CONTROL -
PRE ADVANCED EVAPS
The following pressure test procedure is intended to
provide a method for ensuring that the system does
not leak excessively and will effectively control
evaporative emissions.
Equipment required.
Nitrogen cylinder (compressed air may be used to
pressure the system when there has NEVER been
fuel present in the fuel or evaporative control
systems).
Water manometer (0 - 30" H2O or more).
Pipework and a "T" piece.
Method.
1.Ensure that there is at least two gallons of fuel in
the petrol tank unless there has never been any
fuel in the system.
2.Disconnect, at the adsorption canister, the pipe
to the vapour separator.
3.Connect this pipe to the nitrogen cylinder and
the water manometer using the "T" piece.
4.Pressurize the system to between 26.5 and 27.5
inches of water, allow the reading to stabilize,
then turn off the nitrogen supply.
5.Measure the pressure drop within a period of 2
minutes 30 seconds. If the drop is greater than
2.5 inches of water the system has failed the
test. Note that a fully sealed system will show a
slight increase in pressure.
6.Should the system fail the test, maintain the
pressure in the system and apply a soap
solution round all the joints and connections until
bubbles appear to reveal the source of the leak.
7.Repeat the test and if successful, dismantle the
test equipment and reconnect the pipe to the
adsorption canister.LEAK DETECTION PROCEDURE - ADVANCED
EVAPS
1.Connect TestBook to the vehicle and confirm
that the fault code(s) displayed relate to an
EVAP system fault.
2.Examine components in fuel and EVAP system
for damage or poorly connected joints.
3.Repair or replace components to rectify any
faults found, then reset the Check Engine light
using TestBook.
4.Carry out Drive Cycle,
See Drive Cycle -
Advanced EVAPS
5.Using TestBook confirm that the Evaporative
Loss Control (ELC) Inspection and Maintenance
(IM) flag has cleared. This procedure should
confirm that the ELC test was carried out during
the drive cycle and that the fault was cured.
6.If the IM flag is still shown, use TestBook to
interrogate the engine management system to
ascertain which of the following situations exists:
·If a fault code is shown then further investigation
is required, proceed to the next step.
·If the IM flag is still shown, but no faults are
indicated the conditions for the ELC check have
not been met and the drive cycle must be
repeated.
7.Connect the Leak Detection/EVAP Diagnostic
Station to the vehicle and carry out the
procedures given in the operating instructions
supplied with the equipment.
8.Rectify faults indicated by the Leak
Detection/EVAP Diagnostic Station and return to
step 4.

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REPAIR HEATED OXYGEN SENSOR (HO2S) - 4.0 V8
WARNING: Do not attempt HO2S removal
when the exhaust is hot.
Remove
For all sensors:
1.Raise and support front of vehicle.
2.Release sensor lead from clips.
RH front sensor only
3.Remove nuts retaining coil bracket and position
bracket aside.
See FUEL SYSTEM SFI, Repair,
Ignition Coils
4.Release multiplug from bracket behind cylinder
head.
5.Disconnect multiplug and release sensor lead
from clip.
6.Unscrew and remove sensor from exhaust pipe.LH front sensor
7.Disconnect multiplug and release from bracket.
8.Unscrew and remove sensor from exhaust pipe
using special tool LRT-12-047 (LST134).