ECO mode JAGUAR XJ6 1997 2.G Owner's Manual

4Refitting is the reverse of the removal
procedure.
5Run the engine and check for proper
functioning of the heater (and air conditioning,
if equipped).
Control checks
6The climate-control system uses an all-
electronic control panel that sends digital
information to the climate control computer.
There is little the home mechanic can do to
troubleshoot or test the system. The factory
recommends that diagnosis be performed at a
dealership.
7If there is a problem in just one area of
climate control, put the controls through their
entire range of operation and check the
system responses, i.e. set the controls to
COLD, the fan to low and the temperature to
65° F. In this mode the Manual LED should be
lit and the air conditioning compressor should
engage. Try all of the fan speeds and try the
temperature on HOT, then feel for warm air
coming from the ducts. Note:Between each
try of the different controls, wait 20 seconds or
so for the heater/air conditioning system to
adjust before checking for a response.
8When each control button is pushed two
times, its LED light should go on or off. Renew
the control assembly if any of the warning
lights don’t work.
9On 1988 and 1989 models, if the climate
controls do not respond to any driver input,
check with your Jaguar dealer before
renewing the ECU or control panel. A service
part is available (a resistor, #JLM 1901) that
can be installed at one of the control panel
terminals that may fix the problem without any
other parts being renewed. Instructions are
included with the part.
10Check the vacuum lines to the several
vacuum motors that operate the heater/air
conditioning functions. Look for pinched or
blocked hoses and leaks.11Each of the vacuum “servo motors” in the
system can be checked with a hand-held
vacuum pump (see illustration). Apply vacuum
and watch that the door or control it operates is
working.
12Further diagnosis of the controls or
climate control ECU are best left to a Jaguar
dealership or other qualified repair facility.
13 Air conditioning and heating
system- check and
maintenance
1
Air conditioning system
Warning: The air conditioning
system is under high pressure.
Do not loosen any hose fittings
or remove any components until
the system has been discharged. Air
conditioning refrigerant should be properly
discharged into an EPA-approved
recovery/recycling unit by a dealer service
department or an automotive air
conditioning repair facility. Always wear
eye protection when working near air
conditioning system fittings.
1The following maintenance checks should
be performed on a regular basis to ensure that
the air conditioner continues to operate at
peak efficiency:
a) Inspect the condition of the compressor
drivebelt. If it is worn or deteriorated,
renew it (see Chapter 1).
b) Check the drivebelt tension and, if
necessary, adjust it (see Chapter 1).
c) Inspect the system hoses. Look for
cracks, bubbles, hardening and
deterioration. Inspect the hoses and all
fittings for oil bubbles or seepage. If there
is any evidence of wear, damage or
leakage, renew the hose(s).d) Inspect the condenser fins for leaves,
bugs and any other foreign material that
may have embedded itself in the fins. Use
a “fin comb” or compressed air to remove
debris from the condenser.
e) Make sure the system has the correct
refrigerant charge.
2It’s a good idea to operate the system for
about ten minutes at least once a month. This
is particularly important during the winter
months because long term non-use can
cause hardening, and subsequent failure, of
the seals.
3Leaks in the air conditioning system are
best spotted when the system is brought up
to operating temperature and pressure, by
running the engine with the air conditioning
ON for five minutes. Shut the engine off and
inspect the air conditioning hoses and
connections. Traces of oil usually indicate
refrigerant leaks.
4Because of the complexity of the air
conditioning system and the special
equipment required to effectively work on it,
accurate troubleshooting of the system
should be left to a professional technician.
5If the air conditioning system doesn’t
operate at all, check the fuse panel and the air
conditioning relay (refer to Chapter 12 for
relay locations and testing). See Sections 4, 9
and 12 for electrical checks of heating/air
conditioning system components.
6The most common cause of poor cooling is
simply a low system refrigerant charge. If a
noticeable drop in cool air output occurs, the
following quick check will help you determine
if the refrigerant level is low.
Checking the refrigerant charge
7Warm the engine up to normal operating
temperature.
8Place the air conditioning temperature
selector at the coldest setting and put the
Cooling, heating and air conditioning systems 3•11
3
3261 Jaguar XJ6 12.3b Remove the four screws (three are shown here) holding the
control assembly in the control/radio housing
12.11 Check the operation of the vacuum servo motors; in this
case, vacuum is applied to the servo on the right blower case -
the flapper door (arrowed) should operate

blower at the highest setting. Open the doors
(to make sure the air conditioning system
doesn’t cycle off as soon as it cools the
passenger compartment).
9With the compressor engaged - the clutch
will make an audible click and the centre of
the clutch will rotate. After the system reaches
operating temperature, feel the two pipes
connected to the evaporator at the bulkhead
(see illustration).
10The pipe (thinner tubing) leading from the
condenser outlet to the evaporator should be
cold, and the evaporator outlet line (the
thicker tubing that leads back to the
compressor) should be slightly colder (3 to
10° F). If the evaporator outlet is considerably
warmer than the inlet, the system needs a
charge. Insert a thermometer in the centre air
distribution duct while operating the air
conditioning system - the temperature of the
output air should be 35 to 40° F below the
ambient air temperature (down to approxi-
mately 40° F). If the ambient (outside) air
temperature is very high, say 110° F, the duct
air temperature may be as high as 60° F, but
generally the air conditioning is 30 to 50° F
cooler than the ambient air. If the air isn’t as
cold as it used to be, the system probably
needs a charge. Further inspection or testing
of the system is beyond the scope of the
home mechanic and should be left to a
professional.
11Inspect the sight glass (see illustration).
If the refrigerant looks foamy when running,
it’s low. When ambient temperatures are very
hot, bubbles may show in the sight glass even
with the proper amount of refrigerant. With the
proper amount of refrigerant, when the air
conditioning is turned off, the sight glass
should show refrigerant that foams, then
clears. Note:1993 and 1994 models are
equipped with R-134a refrigerant systems and
do not have a sight glass.Heating systems
12If the air coming out of the heater vents
isn’t hot, the problem could stem from any of
the following causes:
a) The thermostat is stuck open, preventing
the engine coolant from warming up
enough to carry heat to the heater core.
Renew the thermostat (see Section 3).
b) A heater hose is blocked, preventing the
flow of coolant through the heater core.
Feel both heater hoses at the bulkhead.
They should be hot. If one of them is cold,
there is an obstruction in one of the hoses
or in the heater core, or the heater control
valve is shut. Detach the hoses and back
flush the heater core with a water hose. If
the heater core is clear but circulation is
impeded, remove the two hoses and flush
them out with a water hose.
c) If flushing fails to remove the blockage
from the heater core, the core must be
renewed.(see Section 11).
13If the blower motor speed does not
correspond to the setting selected on the
blower switch, the problem could be a badfuse, circuit, control panel or climate control
computer (see Sections 10 and 12).
14If there isn’t any air coming out of the
vents:
a) Turn the ignition ON and activate the fan
control. Place your ear at the heating/air
conditioning register (vent) and listen.
Most motors are audible. Can you hear
the motor running?
b) If you can’t (and have already verified that
the blower switch and the blower motor
resistor are good), the blower motor itself
is probably bad (see Section 10).
15If the carpet under the heater core is
damp, or if antifreeze vapour or steam is
coming through the vents, the heater core is
leaking. Remove it (see Section 11) and refit a
new unit (most radiator shops will not repair a
leaking heater core).
16Inspect the drain hose from the heat/AC
assembly at the right side of the bulkhead,
make sure it is not clogged (see illustration).
If there is a humid mist coming from the
system ducts, this hose may be plugged. In
some early models, the hose may have been
pinched during assembly or blocked with
insulation or underseal.
14 Air conditioning
receiver/drier-
removal and refitting
4
Warning: The air conditioning
system is under high pressure.
Do not loosen any hose fittings
or remove any components until
the system has been discharged. Air
conditioning refrigerant should be properly
discharged into an EPA-approved recovery/
recycling unit by a dealer service depart-
ment or an automotive air conditioning
3•12 Cooling, heating and air conditioning systems
13.16 This drain hose (arrowed) from the
heater/air conditioning unit should be kept
clear to allow drainage of condensation
3261 Jaguar XJ6 13.9 Feel the inlet (small arrow) and outlet (large arrow) pipes at
the bulkhead leading to the air conditioning evaporator (battery
removed here for clarity only)
13.11 The sight glass (arrowed) is located on the top of the
receiver/drier, to the right of the radiator

repair facility. Always wear eye protection
when working near air conditioning system
fittings.
1Have the refrigerant discharged and
recovered by an air conditioning technician.
2Disconnect the refrigerant lines (see
illustration)from the receiver/drier and cap
the open fittings to prevent entry of moisture.
3Remove the three nuts holding the
receiver/drier to the radiator support and
remove the receiver/drier. Note:On 1993 and
1994 models, the receiver/drier is a long
tubular style mounted to the top-front of the
radiator support. The grille must be removed
for access on these models (see Chapter 11
for grille removal).
4Refitting is the reverse of removal.
5Have the system evacuated, charged and
leak tested by the workshop that discharged
it. If the receiver/drier was renewed, have
them add new refrigeration oil to the
compressor, about 28 cc (one ounce). Use
only the refrigerant oil compatible with the
refrigerant of your system (R-12 or R-134a).
15 Air conditioning
compressor-
removal and refitting
4
Warning: The air conditioning
system is under high pressure.
Do not loosen any hose fittings
or remove any components until
the system has been discharged. Air
conditioning refrigerant should be properly
discharged into an EPA-approved
recovery/recycling unit by a dealer service
department or an automotive air
conditioning repair facility. Always wear
eye protection when disconnecting air
conditioning system fittings.
1Have the refrigerant discharged by an
automotive air conditioning technician.2Disconnect 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.
3Remove the drivebelt from the compressor
(see Chapter 1).
4Detach the electrical connector and
disconnect the flexible refrigerant lines (see
illustration).
5Unbolt the compressor and lift it from the
vehicle (see illustration).
6If a new or rebuilt compressor is being
installed, drain the fluid from the new unit by
opening the drain plug and by tilting the
compressor to the rear so that any remaining
oil will come out the ports in the back normally
covered by the plate and hard lines. Refit the
drain plug and end-plate and add 199 cc
(7 fluid ounces) of new oil of a type compatible
with the type refrigerant in your system.
7Refitting is the reverse of removal. Renew
any O-rings with new ones specifically made
for the type of refrigerant in your system and
lubricate them with refrigerant oil, also
designed specifically for your refrigerant.
8Have the system evacuated, recharged and
tested by the workshop that discharged it.
16 Air conditioning condenser-
removal and refitting
4
Warning: The air conditioning
system is under high pressure.
Do not loosen any hose fittings
or remove any components until
the system has been discharged. Air
conditioning refrigerant should be properly
discharged into an EPA-approved
recovery/recycling unit by a dealer service
department or an automotive air con-
ditioning repair facility. Always wear eye
protection when disconnecting air
conditioning system fittings.
1Have the refrigerant discharged and
recovered by an air conditioning technician.
2Remove the radiator cowl panel as
described in Section 5.
3Using two spanners to avoid twisting the
fittings, disconnect the inlet and outlet lines
from the condenser (see illustration).
4Pull the condenser straight up and out of
the vehicle.
5Refitting is the reverse of removal. When
refitting the condenser, be sure the rubber
Cooling, heating and air conditioning systems 3•13
3
15.5 Remove the lower mounting bolts
and the adjuster bolt (arrowed)16.3 Disconnect the two lines, then pull up
on the condenser (arrowed)
3261 Jaguar XJ6 14.2 After the system has been discharged, unbolt the two
refrigerant lines (left arrows) from the top of the receiver/drier and
cap them - use two spanners when loosening or tightening these
lines - right arrows indicate the two top mounting bolts
15.4 Disconnect the electrical connector (small arrow) at the
compressor, then disconnect the bolt (large arrow) at the
retaining plate that holds the two hoses in place

cushions fit on the mounting points and that
any foam insulator strips are still in place or
transferred to the new condenser.
6Reconnect the refrigerant lines, using new
O-rings. If a new condenser has been
installed, add 84 cc (3 fluid ounces) of new
refrigerant oil. Note:The oil and O-rings must
be compatible with the type of refrigerant you
are using.
7Refit the remaining parts in the reverse
order of removal.
8Have the system evacuated, charged and
leak tested by the workshop that discharged
it.
17 Air conditioning evaporator
and expansion valve-
removal and refitting
4
Warning 1: The air conditioning
system is under high pressure.
Do not loosen any hose fittings
or remove any components until
the system has been discharged. Air
conditioning refrigerant should be properly
discharged into an EPA-approved
recovery/recycling unit by a dealer service
department or an automotive airconditioning repair facility. Always wear
eye protection when disconnecting air
conditioning system fittings.
Warning 2: Later model vehicles
are equipped with airbags. To
prevent the accidental
deployment of the airbag, which
could cause personal injury or damage to
the airbag system, DO NOT work in the
vicinity of the steering wheel or instrument
panel. The manufacturer recommends
that, on airbag-equipped models, the
following procedure should be left to a
dealer service department or other repair
workshop because of the special tools and
techniques required to disable the airbag
system.
1Refer to Chapter 11 for removal of the glove
compartment, under-dash panels and
console. Note:The removal of the
heater/evaporator housing is difficult and
time-consuming, much more so than the
removal of the heater core (see Section 11).
For some home mechanics, the job is better
left to a Jaguar dealership or other qualified
repair workshop.
2Disconnect the air conditioning lines from
the backside of the expansion valve (at the
bulkhead, just to the right of the engine), usingtwo spanners (see illustration). Cap the open
fittings and expansion valve after dismantling
to prevent the entry of air or dirt.
3Refer to Section 11 for moving the climate-
control computer aside and disconnecting the
heater core pipes.
4From the engine side of the bulkhead, near
the expansion valve, remove the nut retaining
the heat/air conditioning assembly housing
(see illustration). Another mounting nut is on
the left side, under the wiper motor (see
illustration 11.2).
5Disconnect the defroster ducts on the left
and right side of the evaporator housing (see
illustration).
6Identify all of the vacuum motor lines with
masking tape and a felt pen, then disconnect
the lines. Note:Most vacuum lines are colour-
coded. Make notes on which ones go to
which devices.
7Tag and disconnect the wiring plugs
connected to the heating/air conditioning
housing.
8At the bottom left and bottom right of the
housing, pull off the rubber drain tubes that go
into the flooring.
9Remove the four rod-type support braces.
Two support the dash, and two connect the
case to the floor of the car (see illustrations).
3•14 Cooling, heating and air conditioning systems
17.5 Left duct (large arrow) can be removed
by pulling off the clip (small arrow) - right
duct pulls out without a clip17.9a Unbolt the four support braces
(small arrows) from the case (large arrow)
and floor17.9b Black case-support rods are held
with nuts (arrowed), the gold dash-support
rods are retained by a bolt/nut to the dash
3261 Jaguar XJ6 17.2 Use two spanners when disconnecting the air conditioning
lines (arrowed) at the bulkhead, on the backside of the expansion
valve - one spanner holds the body of the expansion valve
17.4 Remove the housing retaining nut (arrowed) on the engine
side of the bulkhead, near the expansion valve - another nut is on
the right, near the heater core pipes

3261 Jaguar XJ6
4
Chapter 4
Fuel and exhaust systems
Fuel system
Fuel pressure:kPa psi
Ignition ON, engine not running . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 to 300 38 to 44
Engine idling:
Vacuum hose detached from fuel pressure regulator . . . . . . . . . . . 280 to 320 40 to 46
Vacuum hose attached to fuel pressure regulator . . . . . . . . . . . . . 210 to 260 30 to 38
Fuel system hold pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 21
Fuel injector resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.0 to 3.0 ohms
Idle speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Must be set by authorised service department
Torque wrench settingsNm lbf ft
Throttle body mounting bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 14
Fuel rail mounting bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9 Accelerator cable - removal, refitting and adjustment . . . . . . . . . . . 10
Air cleaner assembly - removal and refitting . . . . . . . . . . . . . . . . . . . 9
Catalytic converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 6
CHECK ENGINE light . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 6
Electronic Fuel Injection (EFI) system - check . . . . . . . . . . . . . . . . . . 12
Electronic Fuel Injection (EFI) system - component check
and renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Electronic Fuel Injection (EFI) system - general information . . . . . . . 11
Exhaust manifold - removal and refitting . . . . . . . . . . . See Chapter 2A
Exhaust system check . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Exhaust system servicing - general information . . . . . . . . . . . . . . . . 14
Fuel filter renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1Fuel level sender unit - check and renewal . . . . . . . . . . . . . . . . . . . . 5
Fuel lines and fittings - inspection and renewal . . . . . . . . . . . . . . . . 6
Fuel pressure relief . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Fuel pump - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Fuel pump/fuel pressure - check . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Fuel system check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Fuel tank - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Fuel tank cap gasket renewal . . . . . . . . . . . . . . . . . . . . . See Chapter 1
Fuel tank cleaning and repair - general information . . . . . . . . . . . . . 8
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Intake manifold - removal and refitting . . . . . . . . . . . . See Chapter 2A
Underbonnet hose check and renewal . . . . . . . . . . . . . . See Chapter 1
4•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
The fuel system consists of a fuel tank, an
electric fuel pump either located externally,
next to the fuel tank (1988 to 1990 models) or
in the fuel tank (1991 to 1994 models), an EFI
fuel pump relay and main relay, an inertia
switch, fuel injectors and fuel rail, an air
cleaner assembly and a throttle body unit.
Multi Point Fuel Injection (MPFI)
system
Multi point fuel injection uses timed
impulses to sequentially inject the fuel directly
into the intake port of each cylinder. Theinjectors are controlled by the Electronic
Control Unit (ECU). The ECU monitors various
engine parameters and delivers the exact
amount of fuel, in the correct sequence, into
the intake ports. The throttle body serves only
to control the amount of air passing into the
system. Because each cylinder is equipped
with an injector mounted immediately
adjacent to the intake valve, much better
control of the fuel/air mixture ratio is possible.
Fuel pump and lines
Fuel is circulated from the fuel tank to the
fuel injection system, and back to the fuel
tank, through a pair of metal lines running
along the underside of the vehicle. On early
models (1988 to 1990), an electric fuel pump
is attached to the chassis next to the fueltank. On later models (1991 to 1994), the fuel
pump and fuel level sender unit are located
inside the fuel tank. A vapour return system
routes all vapours and hot fuel back to the fuel
tank through a separate return line.
The fuel pump will operate as long as the
engine is cranking or running and the ECU is
receiving ignition reference pulses from the
electronic ignition system (see Chapter 5). If
there are no reference pulses, the fuel pump
will shut off after 2 or 3 seconds.Inertia switch
These models are equipped with an inertia
switch that is wired in the circuit between the
fuel pump relay, the ignition switch and the
fuel pump (refer to the wiring diagrams at the
end of Chapter 12). The inertia switch is a

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

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) . . .