fuel line JAGUAR XJ6 1997 2.G User Guide

special electrical device that provides circuit
protection by switching off the ignition and
fuel pump upon impact in the event of vehicle
collision. Later Jaguar models are equipped
with an additional specialised inertia switch.
This later device switches OFF all ignition fed
circuits, locks the fuel filler cap, locks the boot
(only if doors are locked) and unlocks the
doors if they are locked during the accident.
All these functions are directed by the inertia
switch. The inertia switch is located behind
the left kick panel. Refer to Chapter 12 for
more information.
Exhaust system
The exhaust system includes an exhaust
manifold equipped with an exhaust oxygen
sensor, a catalytic converter, an exhaust pipe,
and a silencer.
The catalytic converter is an emission
control device added to the exhaust system to
reduce pollutants. A single-bed converter is
used in combination with a three-way
(reduction) catalyst. See Chapter 6 for more
information regarding the catalytic converter.
2 Fuel pressure relief
1
Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system.
Don’t smoke or allow open flames or bare
light bulbs near the work area, and don’t
work in a garage where a natural gas-type
appliance (such as a water heater or a
clothes dryer) with a pilot light is present.
Since petrol is carcinogenic, wear latex
gloves when there’s a possibility of being
exposed to fuel, and, if you spill any fuel on
your skin, rinse it off immediately with soap
and water. Mop up any spills immediately
and do not store fuel-soaked rags wherethey could ignite. The fuel system is under
constant pressure, so, if any fuel lines are
to be disconnected, the fuel pressure in
the system must be relieved first. When
you perform any kind of work on the fuel
system, wear safety glasses and have a
Class B type fire extinguisher on hand.
1Before servicing any fuel system
component, you must relieve the fuel pressure
to minimise the risk of fire or personal injury.
2Remove the fuel filler cap - this will relieve
any pressure built up in the tank.
3Remove the fuel pump relay from the main
relay panel (see illustrations). Note:These
models are equipped with a fuel pump relay
that is located in various areas of the vehicle
depending on the year. On 1988 and 1989
models, the fuel pump relay is under the
glovebox. On 1990 to 1992 models, the fuel
pump relay is in the engine compartment on
the left side, attached to the brake pedal
hanger. On 1993 models, the fuel pump relay
is in the boot. On 1994 models, it’s in the
engine compartment on the right side of the
bulkhead. Refer to the relay location charts in
Chapter 12 for additional information.
4Start the engine and wait for the engine to
stall, then turn the ignition key to Off.
Disconnect the cable from the negativeterminal of the battery before beginning any
work on the fuel system.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
5The fuel system is now depressurised.
Note:Place a rag around the fuel line before
removing any hose clamp or fitting to prevent
any residual fuel from spilling onto the engine.
3 Fuel pump/fuel pressure-
check
2
Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. See
the Warning in Section 2.
Note: To perform the fuel pressure test, you
will need to obtain a fuel pressure gauge and
adapter set (fuel line fittings).
Note: On 1988 to 1990 models, the fuel pump
may chatter excessively and the engine may
stall frequently during hot weather. If stalling
occurs, the engine will restart after a cool-
down period. Dual fuel pumps can be installed
by a dealer service department or other
qualified repair facility to remedy this problem.
Preliminary inspection
1Should the fuel system fail to deliver the
proper amount of fuel, or any fuel at all,
inspect it as follows. Remove the fuel filler
cap. Have an assistant turn the ignition key to
the ON position (engine not running) while you
listen at the fuel filler opening. You should
hear a whirring sound that lasts for a couple of
seconds. On 1988 to 1990 models, listen
behind the left rear wheel (external fuel pump)
for the fuel pump sound.
2If you don’t hear anything, check the fuel
pump relay (see illustration 2.3a, b or c)and
4•2 Fuel and exhaust systems
2.3c On 1992 models, the fuel pump relay
is located in the left rear corner of the
engine compartment
3261 Jaguar XJ6 2.3a Relay locations on a 1988 model
2.3b Relay locations on a 1989 model

circuit. If all circuits are intact and not
damaged, check the inertia switch. Note: The
inertia switch is a special device that shuts
down power to the ignition and the fuel pump
in the event of an accident. See Chapter 12 for
checking and resetting procedures for the
inertia switch.
3Remove the relay and check for battery
voltage to the fuel pump relay connector (see
illustration). If there is battery voltage
present, check the relay for proper operation.
Refer to the relay checking procedure in
Chapter 12. Note:If battery voltage is not
available, check for battery voltage to the main
relay(see illustration). Refer to the relay
location diagrams in Chapter 12. The main
relay, which is located next to the fuel pump
relay, supplies voltage to the fuel pump and
ignition system.
4If battery voltage is present, check for
battery voltage directly at the fuel pump
electrical connector (see illustrations), within
two seconds of the ignition key being turned
On. If there is no voltage, check the fuel pump
circuit. If there is voltage present, renew the
pump (see Section 4). Note:It will be
necessary to raise the vehicle and support it
securely on axle stands to gain access to the
fuel pump electrical connectors. Have an
assistant operate the ignition key and be sure
to block the front wheels to avoid any
movement of the vehicle.
Operating pressure check
5Relieve the fuel system pressure (see
Section 2). Detach the cable from the negative
battery terminal.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
6Detach the fuel line from the fuel rail and
connect a fuel pressure gauge(see
illustrations)between the fuel pulsationdamper and the fuel rail. Tighten the hose
clamps securely.
7Attach the cable to the negative battery
terminal. Start the engine.
8Note the fuel pressure and compare it with
the pressure listed in this Chapter’s
Specifications.
9Disconnect the vacuum hose from the fuelpressure regulator and hook up a hand-held
vacuum pump (see illustration)to the port on
the fuel pressure regulator.
10Read the fuel pressure gauge with vacuum
applied to the pressure regulator and also with
no vacuum applied. The fuel pressure should
decrease as vacuum increases (and increase
as vacuum decreases).
Fuel and exhaust systems 4•3
4
3261 Jaguar XJ6 3.3a Checking for battery voltage at the fuel pump relay
connector ( 1989 model)
3.3b Checking for battery voltage to the main relay (1989 model)
3.6a Remove the fuel line from the fuel
pulsation damper . . .
3.4b Check for battery voltage to the
fuel pump on the harness connector near
the fuel tank on models with in-tank
fuel pumps3.4a Remove the rubber boot from the fuel
pump electrical connector and check for
voltage while an assistant turns the
ignition key (1989 model shown)
3.6b . . . then refit the fuel pressure gauge
between the fuel rail and the fuel pressure
damper using a T-fitting

11Reconnect the vacuum hose to the
regulator and check the fuel pressure at idle,
comparing your reading with the value listed
in this Chapter’s Specifications. Disconnect
the vacuum hose and watch the gauge - the
pressure should jump up considerably as
soon as the hose is disconnected. If it
doesn’t, check for a vacuum signal to the fuel
pressure regulator (see Step 14).
12If the fuel pressure is low, pinch the fuel
return line shut (see illustration)and watch
the gauge. If the pressure doesn’t rise, the
fuel pump is defective or there is a restriction
or leak in the fuel feed line, or the pump is
faulty. If the pressure rises sharply, renew the
pressure regulator.
13If the fuel pressure is too high, turn the
engine off. Disconnect the fuel return line and
blow through it to check for a blockage. If
there is no blockage, renew the fuel pressure
regulator.
14Connect a vacuum gauge to the pressure
regulator vacuum hose. Start the engine and
check for vacuum (see illustration). The fuel
pressure regulator receives manifold vacuum
that decreases (increases fuel pressure) when
the engine speed is raised (acceleration). If
there isn’t vacuum present, check for a
clogged hose or vacuum port. If the amount ofvacuum is adequate but the pressure is too
high, renew the fuel pressure regulator.
15Turn the ignition switch to OFF, wait five
minutes and recheck the pressure on the
gauge. Compare the reading with the
specified hold pressure. If the hold pressure is
less than specified:
a) The fuel lines may be leaking.
b) The fuel pressure regulator may be
allowing the fuel pressure to bleed
through to the return line.
c) A fuel injector (or injectors) may be
leaking.
d) The fuel pump may be defective.
4 Fuel pump-
removal and refitting
3
Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. See
the Warning in Section 2.
Note 1:On early models (1988 to 1990), an
electric fuel pump is attached to the chassis
next to the fuel tank. On later models (1991 to
1994), the fuel pump is inside the fuel tank.
Note 2: On 1988 to 1990 models, the fuel
pump may chatter excessively and the engine
may stall frequently during hot weather. If
stalling occurs, the engine will restart after a
cool-down period. Dual fuel pumps can be
installed by a dealer service department or
other qualified repair facility to remedy this
problem.
1Remove the fuel tank filler cap to relieve
any pressure in the fuel tank. Relieve the fuel
pressure (see Section 2).
2Disconnect the cable from the negative
terminal of the battery.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
External fuel pumps
3Raise the vehicle and support it securely on
axle stands.
4Disconnect the fuel lines from the fuel pump.
5Disconnect the electrical connectors from
the fuel pump (see illustration 3.4a).
6Remove the fuel pump bracket retaining
nuts (see illustration).
7Carefully withdraw the fuel pump from the
rubber case inside the fuel pump bracket and
angle the fuel pump over the rear suspension
and out near the wheel on the left side of the
vehicle.
8Refitting is the reverse of removal.
In-tank fuel pumps
9Raise the vehicle and support it securely on
axle stands.
10Disconnect the fuel pump and fuel level
sender unit electrical connectors and the fuel
lines.
11Remove the fuel tank from the boot (see
Section 7).
12Disconnect the fuel lines from the evap-
orative flange (see illustration). Remove the
lock ring with a hammer and brass punch,
tapping the lock ring anti-clockwise.
13Withdraw the fuel pump module from the
fuel tank. Note: The fuel pump module is
4•4 Fuel and exhaust systems
3.14 Connect a vacuum gauge to the
vacuum line leading to the fuel pressure
regulator and check the vacuum source4.6 Remove the fuel pump mounting nuts
(arrowed) and slide the fuel pump out of
the rubber casing (1989 model shown)
3261 Jaguar XJ6 3.9 Check fuel pressure without vacuum applied to the fuel
pressure regulator, then with vacuum applied; fuel pressure
should DECREASE as vacuum INCREASES
3.12 Using a pair of pliers, squeeze the return line and observe
the fuel pressure increase (wrap a rag around the fuel line so you
don’t damage it)

indexed near the bottom, therefore it will be
necessary to turn the module slightly to unlock
it from the rubber holder mounted on the
bottom of the fuel tank.
14Renew the fuel pump module as a single
unit.
15Refitting is the reverse of removal.
5 Fuel level sender unit- check
and renewal
3
Warning: Petrol is highly
flammable, so take precautions
when you work on any part of
the fuel system. See the
Warning in Section 2.
Note:Some 1994 models may be equipped
with faulty fuel level sender units. A tight float
rod bushing may cause the float to stick and
indicate high fuel levels while the tank is
almost empty.
Check
1Before performing any tests on the fuel
level sender unit, completely fill the tank with
fuel.
2Remove the boot liner (see Chapter 12) to
expose the fuel level sender unit access
cover.
3Disconnect the fuel level sender unit
electrical connector located on the accesscover.Note:1991 to 1994 models are
equipped with a fuel pump module and a
sender unit assembly while 1988 and 1989
models are equipped with only the fuel level
sender unit inside the tank.
4Position the ohmmeter probes on the
electrical connector terminals (see
illustration)and check for resistance. Use the
200 ohm scale on the ohmmeter.
5With the fuel tank completely full, the
resistance should be about 18 to 20 ohms.
6Reconnect the electrical connector and
drive it until the tank is nearly empty.
7Check the resistance. The resistance of the
sender unit should be about 190 to 200 ohms.8If the readings are incorrect, renew the
sender unit. Note:The test can also be
performed with the fuel level sender unit
removed from the fuel tank. Using an
ohmmeter, check the resistance of the sender
unit with the swing arm completely down (tank
empty) and with the arm up (tank full) (see
illustration). The resistance should change
steadily from 200 ohms to around 18 ohms.
Renewal
Warning: The fuel level in the
tank must be less than half full
to safely remove the fuel
pump/sender unit assembly from the fuel
Fuel and exhaust systems 4•5
4
5.4 Connect the probes of the ohmmeter
to the fuel level sender unit terminals and
check the resistance of the float assembly5.8 An accurate check of the sender unit
can be made by removing it from the fuel
tank and observing the resistance with the
float down (empty) and then extended (full)
3261 Jaguar XJ6
4.12 Exploded view of the in-
tank fuel pump and the fuel tank
on 1991 to 1994 models

tank. If there is any doubt about the
amount of fuel in the tank, drain the fuel
tank completely before attempting this
procedure (Section 7, paragraph 1).
9Disconnect the cable from the negative
terminal of the battery. Disconnect the fuel level
sender unit/fuel pump electrical connector.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
10Using a brass punch, tap on the lock ring
anti-clockwise (see illustration)until the tabs
align with the indentations in the fuel tank.
11Carefully angle the sender unit out of the
opening without damaging the fuel level float
(see illustration).
12Refitting is the reverse of removal.
6 Fuel lines and fittings-
inspection and renewal
2
Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. See
the Warning in Section 2.
Note:If there is a distinct knocking noise
coming from the dash when the engine is
idling, the fuel feed hose may have hardened,
restricting fuel flow and causing abnormal
sounds. Replace the fuel inlet (feed) hose with
a new one.
Inspection
1Once in a while, you will have to raise the
vehicle to service or renew some component
(an exhaust pipe hanger, for example).
Whenever you work under the vehicle, always
inspect fuel lines and all fittings and
connections for damage or deterioration.
2Check all hoses and pipes for cracks, kinks,
deformation or obstructions.
3Make sure all hoses and pipe clips attach
their associated hoses or pipes securely to
the underside of the vehicle.4Verify all hose clamps attaching rubber
hoses to metal fuel lines or pipes are a tight fit
between the hoses and pipes.
Renewal
5If you must renew any damaged sections,
use hoses or pipes constructed from exactly
the same material as the section you are
replacing. Do not refit substitutes constructed
from inferior or inappropriate material or you
could cause a fuel leak or a fire.
6Always, before detaching or disassembling
any part of the fuel line system, note the
routing of all hoses and pipes and the
orientation of all clamps and clips to assure
that new sections are identically installed.
7Before detaching any part of the fuel
system, be sure to relieve the pressure in the
tank by removing the fuel tank cap, then
relieve the fuel system pressure (Section 2).
Cover the fitting being disconnected with a
rag to absorb any fuel that may leak out.
7 Fuel tank-
removal and refitting
3
Warning: Petrol is extremely
flammable, so take extra
precautions when you work onany part of the fuel system. See the
Warning in Section 2.
1This procedure is much easier to perform if
the fuel tank is empty. Some models may have
a drain plug for this purpose. If for some reason
the drain plug can’t be removed, postpone the
job until the tank is empty or siphon the fuel
into an approved container using a siphoning
kit (available at most motor factors).
Warning: Do not start the
siphoning action by mouth!
2Remove the fuel filler cap to relieve fuel
tank pressure.
3Detach the battery negative cable.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
4If the tank is full or nearly full, drain the fuel
into an approved container.
5Raise the vehicle and place it securely on
axle stands.
6Remove the filler neck vent tube clamp (see
illustration)and separate the tube from the
fuel filler neck.
7Remove the fuel filler assembly bolts (see
illustration)and slide the large rubber boot
down the neck of the fuel tank. Note:These
vehicles are susceptible to clogging of the fuel
overflow line. If this happens, excess fuel or
4•6 Fuel and exhaust systems
7.6 Remove the clamp that retains the fuel
filler assembly to the filler neck7.7a Remove bolts (arrowed) that retain the
fuel filler assembly to the body and slide the
assembly down the filler neck of fuel tank
3261 Jaguar XJ6 5.10 Use a brass punch and remove the lock ring by tapping on it
in an anti-clockwise direction
5.11 Lift the fuel level sender unit assembly from the fuel tank at
an angle so as not to damage the float or arm

water in the fuel filler cap recess could flow
into the boot, causing a dangerous condition
and/or an unpleasant mess. To correct this
condition, direct low-pressure compressed air
into the overflow hole (see illustration), which
should be enough to clear any obstruction in
the line.
8Remove the spare tyre and the spare tyre
bracket assembly (see illustration).
9Disconnect the fuel lines, the vapour return
line and the canister vent line (see
illustrations). Note:Be sure to plug the hoses
to prevent leakage and contamination of the
fuel system.Remove the driveline to gain
access to the fuel line connectors next to the
tank (see Chapter 8). Working under the
vehicle, remove the pins using a needle-nose
pliers, turn the connectors slightly to loosen
them from the grommets and pull the fuel lines
out of the tank.10Remove the retaining bolts from the
fuel tank retaining straps (see illustration).
11Pull the fuel tank out into the boot area.Be careful to angle the fuel filler neck away
from the body.
12Remove the tank from the vehicle.
13Refitting is the reverse of removal.
8 Fuel tank cleaning
and repair-
general information
5
1Any repairs to the fuel tank or filler neck
should be carried out by a professional who
has experience in this critical and potentially
dangerous work. Even after cleaning and
flushing of the fuel system, explosive fumes
can remain and ignite during repair of the tank.
2If the fuel tank is removed from the vehicle,
it should not be placed in an area where
sparks or open flames could ignite the fumes
coming out of the tank. Be especially careful
inside garages where a natural petrol-type
appliance is located, because the pilot light
could cause an explosion.
9 Air cleaner assembly-
removal and refitting
1
1Detach the clips and remove the air filter
cover and the filter element (see Chapter 1).
2Remove the bolts and remove the air cleaner
assembly from the engine compartment (see
illustrations).
3Refitting is the reverse of removal.
Fuel and exhaust systems 4•7
4
7.7b Direct low pressure compressed air
into the hole for the overflow line if clogged7.8 Remove the bolts (arrowed) from the
spare tyre bracket and lift out the assembly7.9a Disconnect the flexible fuel lines from
the metal fuel lines
7.9b Disconnect the vapour return line
from the fuel tank7.9c Disconnect the canister purge line
from the fuel tank
7.9d Remove the clips (arrowed) that
retain the fuel lines to the fuel tank using
needle-nose pliers
3261 Jaguar XJ6
7.10 Remove the tank strap bolts
(arrowed) from the body
9.2a Remove the bolts (arrowed) from the
air cleaner assembly9.2b Also, remove the bolt that retains the
air intake duct to the MAF sensor and lift
the assembly from the compartment

headlights or heated rear window and confirm
that the engine rpm decreases at first and
then increases. This check monitors the ISC
motor as it is signalled by the computer to
increase idle speed due to additional
amperage required from the charging system.
As the headlights draw current from the
charging system, the alternator will create
resistance on the belt as it works to produce
the additional energy. If the rpm does not
increase, check the ISC motor.
23Check for approximately 11.2 volts to the
ISC stepper motor (see illustrations).
Disconnect the ISC harness connector and
working on the harness side, check for
11.2 volts with the ignition key ON (engine not
running). Also, check the corresponding
terminals for the correct voltage amounts. If
the correct voltage does not exist, check the
wiring harness. Refer to the wiring diagrams
at the end of Chapter 12.24The ISC motor or stepper motor can be
checked for correct operation but a special tool
is required to activate the internal coils. Have
the stepper motor checked by a dealer service
department or other qualified repair workshop.
25Reconnect the ISC motor electrical
connector.
Renewal
26Detach the cable from the negative
terminal of the battery (see Cautionat the
beginning of this Section).
27Use a large open-end spanner and
unscrew the ISC motor from the housing (see
illustration).
28Refitting is the reverse of removal, but be
sure to use a new gasket.
Fuel rail and fuel injectors
Note:If there is a distinct knocking noise
coming from the dash when the engine is
idling, the fuel feed hose may have hardenedrestricting fuel flow and causing abnormal
sounds. Replace the fuel inlet (feed) hose with
a new part from the dealer parts department.
Check
29Refer to the fuel injection system checking
procedure (see Section 12).
Renewal
30Relieve the fuel pressure (see Section 2).
31Detach the cable from the negative
terminal of the battery (see Cautionat the
beginning of this Section).
32Disconnect the fuel injector wiring con-
nectors and set the injector wire harness aside.
33Detach the vacuum sensing hose from the
fuel pressure regulator.
34Disconnect the fuel lines from the fuel
pressure regulator and the fuel rail (see
illustration 3.6a)
35Remove the fuel rail mounting bolts (see
illustration).
4•12 Fuel and exhaust systems
3261 Jaguar XJ6 13.23a To check the ISC motor, turn the ignition key ON
(engine not running) and check for the proper voltage amounts
at the harness connector (1989 model shown)
13.23b Later models are equipped with a different shape
ISC connector but the voltage values should be the same
as the early style
13.27 Use a large open end spanner to remove the ISC motor
from the intake manifold13.35 Remove the fuel rail mounting bolts (arrowed) . . .

36Remove the fuel rail with the fuel injectors
attached (see illustration).
37Prise off the clips and remove the fuel
injector(s) from the fuel rail (see illustration).
38If you are replacing the injector(s), discard
the old injector. If you intend to re-use the
same injectors, renew the grommets and
O-rings (see illustrations).
39Refitting of the fuel injectors is the reverse
of removal. Apply a light film of clean engine
oil to the O-rings before refitting them.
40Tighten the fuel rail mounting bolts to the
torque listed in this Chapter’s Specifications.
Fuel pressure regulator
Check
41Refer to the fuel pump/fuel pressure
check procedure (see Section 3).
Renewal
42Relieve the fuel pressure (see Section 2)
and detach the cable from the negative
terminal of the battery (see the Cautionat the
beginning of this Section).
43Detach the vacuum hose from the
regulator.
44Remove the fuel rail and the injectors as
an assembly (see Steps 30 to 39).
45Remove the fuel line from the fuel
pressure regulator (see illustration).
46Remove the fuel pressure regulator
mounting bolts and detach the pressure
regulator from the engine.
47The remainder of refitting is the reverse of
removal. Make sure the fuel lines are secure
and there are no leaks before using the car.
Supplementary air valve
Check
48The supplementary air valve provides
additional throttle valve bypass air during cold
starting and cold running conditions below
15° F. This output actuator is controlled by the
computer (ECU) in response to informationreceived from the coolant temperature sensor,
intake air temperature sensor and other
information sensors working with the fuel
injection system.
49Check for battery voltage to the
supplementary air valve. With the engine cold,
backprobe the electrical connector using a
long pin and check for battery voltage (see
illustration). Voltage should exist.
50Because of the special tools required to
test the supplementary air valve, have it
tested by a dealer service department or other
qualified repair facility.
Renewal
51Remove the intake hoses, the mounting
screws and detach the supplementary air
valve from the engine.
52Refitting is the reverse of removal.
53Be sure to use a new gasket when refitting
the idle-up valve.
Air intake plenum
Note:The air intake plenum is removed and
installed as a complete unit with the intake
manifold. In the event of damage or leaks,
remove the air intake plenum and intake
Fuel and exhaust systems 4•13
4
3261 Jaguar XJ6 13.36 . . . and remove the fuel rail with the fuel injectors attached
13.37 Remove the fuel injector retaining clips from the fuel rail
using a small screwdriver
13.45 Disconnect the fuel pressure
regulator from the fuel return line
13.38b Pick out the old injector seal but
make sure the injector body is not
damaged in the process13.38a If you plan to refit the original
injectors, remove and discard the O-rings
and grommets and fit new ones
13.49 Check for battery voltage to the
supplementary air valve

manifold as a single unit and have it repaired
by a dealer service department. Refer to
Chapter 2 for removal and refitting procedures.
14 Exhaust system servicing-
general information
Warning: Inspection and repair
of exhaust system components
should be done only after the
components have cooled.
1The exhaust system consists of the exhaust
manifold, catalytic converter, the silencer, the
tailpipe and all connecting pipes, brackets,
hangers and clamps. The exhaust system is
attached to the body with mounting brackets
and rubber hangers (see illustrations). If any
of these parts are damaged or deteriorated,
excessive noise and vibration will be
transmitted to the body. Note:The exhaust
system configuration changes with later model
updates. Earlier models (1988 and 1989) are
equipped with a pre-catalytic converter near
the exhaust manifold incorporating a single
exhaust pipe to the silencer. Later models are
equipped with dual exhaust pipes, dual
catalytic converters and silencers.
2Conducting regular inspections of the
exhaust system will keep it safe and quiet.
Look for any damaged or bent parts, open
seams, holes, loose connections, excessive
corrosion or other defects which could allow
exhaust fumes to enter the vehicle.
Deteriorated exhaust system components
should not be repaired - they should be
replaced with new parts.
3If the exhaust system components are
extremely corroded or rusted together, they
will probably have to be cut from the exhaust
system. The convenient way to accomplish
this is to have a silencer repair workshop
remove the corroded sections with a cutting
torch. If, however, you want to save money by
doing it yourself and you don’t have an
oxy/acetylene welding outfit with a cutting
torch, simply cut off the old components with
a hacksaw. If you have compressed air,
special pneumatic cutting chisels can also beused. If you do decide to tackle the job at
home, be sure to wear eye protection to
protect your eyes from metal chips and work
gloves to protect your hands.
4Here are some simple guidelines to apply
when repairing the exhaust system:
a) Work from the back to the front when
removing exhaust system components.
b) Apply penetrating oil to the exhaust
system component fasteners to make
them easier to remove(see illustration).
c) Use new gaskets, hangers and clamps
when refitting exhaust system components.
d) Apply anti-seize compound to the threads
of all exhaust system fasteners during
reassembly.e) Be sure to allow sufficient clearance
between newly installed parts and all
points on the underbody to avoid
overheating the floor pan and possibly
damaging the interior carpet and
insulation. Pay particularly close attention
to the catalytic converter and its heat
shield.
Warning: The catalytic converter
operates at very high tem-
peratures and takes a long time
to cool. Wait until it’s completely
cool before attempting to remove the
converter. It’s a good idea to wear suitable
gloves. Failure to observe these points
could result in serious burns.
4•14 Fuel and exhaust systems
14.1c On dual silencer models, check the
condition of the mount (arrowed)
and the clamps
14.1a The rear tailpipe section is fastened
to the chassis with a special rubber mount
(arrowed) that pivots with road movement.
Check for deterioration and alignment14.1b Check the condition of the flexible
rubber mounts that hang the silencer to
the chassis
14.4 Use penetrating spray on the exhaust
flange nuts before attempting to
remove them
3261 Jaguar XJ6

3261 Jaguar XJ6
6
Chapter 6
Emissions and engine control systems
EGR gas temperature sensor resistance
Temperature:
212° F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 to 100 k-ohms
400° F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 to 8 k-ohms
662° F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 to 350 ohms
Torque wrench settingNm lbf ft
Crankshaft sensor bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 20 Air Injection Reactor (AIR) system . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Catalytic converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
CHECK ENGINE light . . . . . . . . . . . . . . . . . . . . . . . . . . . See Section 3
Crankcase ventilation system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electronic control system and ECU . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Evaporative Emission Control (EVAP) system . . . . . . . . . . . . . . . . . . 6Exhaust Gas Recirculation (EGR) system . . . . . . . . . . . . . . . . . . . . . 6
Fuel tank cap gasket renewal . . . . . . . . . . . . . . . . . . . . . See Chapter 1
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Information sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
On Board Diagnosis (OBD) system -
description and fault code access . . . . . . . . . . . . . . . . . . . . . . . . . 3
6•1
Specifications Contents
Easy,suitable for
novice with little
experienceFairly easy,suitable
for beginner with
some experienceFairly difficult,
suitable for competent
DIY mechanic
Difficult,suitable for
experienced DIY
mechanicVery difficult,
suitable for expert DIY
or professional
Degrees of difficulty
54321
1 General information
To minimise pollution of the atmosphere
from incompletely burned and evaporating
gases and to maintain good driveability and
fuel economy, a number of emission control
systems are used on these vehicles. They
include the:
Air Injection Reactor (AIR) system
Crankcase Ventilation system
Exhaust Gas Recirculation (EGR) system
Electronic Fuel Injection (EFI) system
Evaporative Emission Control (EVAP)
system
Three-way catalytic converter (TWC)
system
The sections in this chapter include general
descriptions, checking procedures within the
scope of the home mechanic and component
renewal procedures (when possible) for each
of the systems listed above.
Before assuming an emissions control
system is malfunctioning, check the fuel and
ignition systems carefully (Chapters 4 and 5).
The diagnosis of some emission control
devices requires specialised tools, equipment
and training. If checking and servicing becometoo difficult or if a procedure is beyond the
scope of your skills, consult your dealer
service department or other repair workshop.
This doesn’t mean, however, that emission
control systems are particularly difficult to
maintain and repair. You can quickly and
easily perform many checks and do most of
the regular maintenance at home with
common tune-up and hand tools. Note:The
most frequent cause of emission problems is
simply a loose or broken electrical connector
or vacuum hose, so always check the
electrical connectors and vacuum hoses first.Pay close attention to any special
precautions outlined in this chapter. It should
be noted that the illustrations of the various
systems may not exactly match the system
installed on your vehicle because of changes
made by the manufacturer during production
or from year-to-year.
The Vehicle Emissions Control Information
(VECI) label and a vacuum hose diagram are
located under the bonnet (see illustrations).
These contain important emissions specifi-
cations and setting procedures, and a
vacuum hose schematic with emissions
1.6a The Vehicle Emissions Control
Information (VECI) label shows the types of
emission control systems installed, engine
information, etc (1992 model shown)
1.6b Typical vacuum hose routing label
(1992 model shown)