Ford Mondeo (petrol engines). Manual - part 93

(b) On Estate models, slacken the clamp

immediately above the rear anti-roll bar,
and work the hose off the filler neck stub
(see illustration).

8 Unscrew the six retaining nuts, and
withdraw the exhaust system’s rear heat
shield from the underbody (see illustration).
9 Support the tank with a trolley jack or
similar. Place a sturdy plank between the
support and the tank, to protect the tank.
10 Unscrew the bolt at the front of each
retaining strap, and pivot them down until
they are hanging out of the way. Note the
earth lead under the left-hand strap’s bolt -
clean the mating surfaces before the tank is
refitted, so that clean, metal-to-metal contact
is ensured.
11 Lower the tank enough to unclip the fuel
return pipe (coded red) from its top surface,
then disconnect the charcoal canister’s
vapour hose from the union at the top rear of
the tank (see illustration). If you have any
doubts, clearly label the fuel lines and hoses,
and their respective unions. Plug the hoses, to
prevent leakage and contamination of the fuel
system.
12 Remove the tank from the vehicle,
releasing it from the filler neck stub. While the
tank is removed, unhook the retaining straps
(twist them through 90° to do so), and check
that they and their locations in the underbody
are in good condition.
13 With the fuel tank removed, the filler neck
can be withdrawn. It is secured by a single
screw in the filler opening, and by two bolts to
the underbody.
14 Refitting is the reverse of the removal
procedure.

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. Don’t work in a
garage where a natural gas-type appliance

(such as a water heater or clothes dryer)
with a pilot light is present. If you spill any
fuel on your skin, rinse it off immediately
with soap and water. When you perform
any kind of work on the fuel system, wear
safety glasses, and have a Class B type
fire extinguisher on hand.
1 Any 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.
2 If 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 gas-type
appliance is located, because the pilot light
could cause an explosion.

Warning: The fuel system
pressure must be released before
any part of the system is
disturbed - see Section 2. 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. Don’t work in a garage where a
natural gas-type appliance (such as a
water heater or clothes dryer) with a pilot
light is present. If you spill any fuel on your
skin, rinse it off immediately with soap and
water. When you perform any kind of work
on the fuel system, wear safety glasses,
and have a Class B type fire extinguisher
on hand.
Note: Refer to illustrations 10.4 and 10.11 for
details.
1 Remove the fuel tank (see Section 10).
2 Prise the two valves out of the tank, and
remove the anti-trickle fill valve from its
mounting. Take care not to damage the valves
or the tank. Prise out the rubber seals from

the tank openings, and renew then if they are
worn, distorted, or if either has been leaking.
3 If either valve is thought to be faulty, seek
the advice of a Ford dealer as to whether they
can be renewed individually. If not, the
complete valve and pipe assembly must be
renewed.
4 Refitting is the reverse of the removal
procedure. Ensure that both roll-over valves
are pressed securely into their seals, so that
there can be no fuel leaks.

1 Disconnect the battery negative (earth) lead
- see Chapter 5, Section 1.
2 Remove the trim panel from the left-hand
footwell.
3 Peel back the sound-insulating material
from the switch, and undo its two retaining
screws (see illustration).
4 Unplug the switch electrical connector, and
withdraw the switch.
5 Refitting is the reverse of the removal
procedure. Ensure that the switch is reset by
depressing its red button.

These models are equipped with a

Sequential Electronically-controlled Fuel
Injection (SEFI) system. The system is
composed of three basic sub-systems: fuel
system, air induction system and electronic
control system. Note: Refer to illustrations
2.1A and 2.1B of Chapter 6 for further
information on the components of the system.

Fuel system

An electric fuel pump located inside the fuel

tank supplies fuel under pressure to the fuel
rail, which distributes fuel evenly to all
injectors. A filter between the fuel pump and
the fuel rail protects the components of the
system. A pressure regulator controls the
system pressure in relation to inlet tract
depression. From the fuel rail, fuel is injected

14 Fuel injection system/engine

management system - general
information

13 Fuel cut-off switch - 

removal and refitting

12 Roll-over valves - 

removal and refitting

11 Fuel tank cleaning and repair -

general information

4•8 Fuel and exhaust systems

10.8  Exhaust system must be lowered and

heat shield removed to enable fuel tank

removal - arrows show location of

retaining strap front bolts

10.11  Lower fuel tank - do not distort filler

neck stub (A) - and unclip (red-coded) fuel

return pipe (B), then disconnect charcoal

canister’s vapour hose (C)

13.3  Fuel cut-off switch retaining screws

(arrowed)

into the inlet ports, just above the inlet valves,
by four fuel injectors. The system also
includes features such as the flushing of fresh
(ie, cold) fuel around each injector on start-up,
thus improving hot starts.

The amount of fuel supplied by the injectors

is precisely controlled by an Electronic
Control Unit (ECU). The ECU uses the signals
derived from the engine speed/crankshaft
position sensor and the camshaft position
sensor, to trigger each injector separately in
cylinder firing order (sequential injection), with
benefits in terms of better fuel economy and
lower exhaust emissions.

Air induction system

The air system consists of an air filter

housing, an air mass meter, an intake
resonator and plenum chamber, and a throttle
housing. The air mass meter is an information-
gathering device for the ECU; it uses a “hot-
wire” system to send the ECU a constantly-
varying (analogue) voltage signal
corresponding to the volume of air passing
into the engine. Another sensor in the air mass
meter measures intake air temperature. The
ECU uses these signals to calculate the mass
of air entering the engine.

The throttle valve inside the throttle housing

is controlled by the driver, through the
accelerator pedal. As the valve opens, the
amount of air that can pass through the
system increases. The throttle potentiometer
opens further, the air mass meter’s signal
alters, and the ECU opens each injector for a
longer duration, to increase the amount of fuel
delivered to the inlet ports.

Electronic control system

The ECU controls the fuel injection system,

as well as the other sub-systems which make
up the entire engine management system. It
receives signals from a number of information
sensors, which monitor such variables as
intake air mass and temperature, coolant
temperature, engine speed and position,
acceleration/deceleration, and exhaust gas
oxygen content. These signals help the ECU
determine the injection duration necessary for
the optimum air/fuel ratio. These sensors and
associated ECU-controlled relays are located
throughout the engine compartment. For
further information regarding the ECU and its
control of the engine management system,
see Chapter 6.

Idle speed and mixture
adjustment - general

Both the idle speed and mixture are under

the control of the ECU, and cannot be
adjusted. Not only can they not be adjusted,
they cannot even be checked, except with the
use of special diagnostic equipment (see
Chapter 6) - this makes it a task for a Ford
dealer service department. Do not attempt to
“adjust” these settings in any way without
such equipment.

If the idle speed and mixture are thought to

be incorrect, take the vehicle to a Ford dealer
for the complete system to be tested.

On models equipped with a heated

windscreen, an idle-increase solenoid valve is
fitted, which raises the idle speed to
compensate for the increased load on the
engine when the heated windscreen is
switched on. When the valve is open, air from
the plenum chamber bypasses the throttle
housing and idle speed control valve, passing
directly into the inlet manifold through the
union on its left-hand end. The system is
active only for the four minutes that the
heated windscreen circuit is live, and is
supplementary to the main (ECU-controlled)
idle speed regulation.

Warning: Petrol is extremely
flammable, so extra precautions
must be taken when working on
any part of the fuel system. Do

not smoke, or allow open flames or bare
light bulbs, near the work area. Don’t work
in a garage if a natural gas-type appliance
with a pilot light is present. While
performing any work on the fuel system,
wear safety glasses, and have a dry
chemical (Class B) fire extinguisher on
hand. If you spill any fuel on your skin,
rinse it off immediately with soap and
water.
Note: This is an initial check of the fuel delivery
and air induction sub-systems of the engine
management system, to be carried out in
conjunction with the operational check of the
fuel pump (see Section 8), and as part of the
preliminary checks of the complete engine
management system (see Section 3 of
Chapter 6).
1 Check the earth wire connections for
tightness. Check all wiring and electrical
connectors that are related to the system.
Loose electrical connectors and poor earths
can cause many problems that resemble
more serious malfunctions.
2 Check to see that the battery is fully-
charged. The ECU and sensors depend on an
accurate supply voltage to properly meter the
fuel.
3 Check the air filter element - a dirty or
partially-blocked filter will severely impede
performance and economy (see Chapter 1).
4 If a blown fuse is found, renew it and see if
it blows again. If it does, search for a short-
circuited wire in the harness related to the
system (see Chapter 6).
5 Check the air intake duct from the intake to
the inlet manifold for leaks, which will result in
an excessively-lean mixture. Also check the
condition of the vacuum hoses connected to
the inlet manifold.
6 Remove the plenum chamber from the
throttle housing. Check the throttle valve for
dirt, carbon or other residue build-up. If it’s

dirty, seek the advice of a Ford dealer - since
the electronic control system is designed to
compensate for factors such as the build-up
of dirt in the throttle housing, it may well be
best to leave it dirty, unless the deposits are
extensive. Note: A warning label on the
housing states specifically that the housing
bore and the throttle valve have a special
coating, and must not be cleaned using
carburettor cleaner, as this may damage it.
7 With the engine running, place a
screwdriver or a stethoscope against each
injector, one at a time. Listen through the
screwdriver handle or stethoscope for a
clicking sound, indicating operation.
8 If an injector isn’t operating (or sounds
different from the others), turn off the engine,
and unplug the electrical connector from the
injector. Check the resistance across the
terminals of the injector, and compare your
reading with the resistance value listed in this
Chapter’s Specifications. If the resistance
isn’t as specified, renew the injector.
9 A rough idle, diminished performance
and/or increased fuel consumption could also
be caused by clogged or fouled fuel injectors.
Fuel additives that can sometimes clean
fouled injectors are available at car accessory
shops.
10 The remainder of the system checks
should be left to a dealer service department
or other qualified repair specialist, as there is
a chance that the ECU may be damaged if
tests are not performed properly.

Warning: The fuel system
pressure must be released before
any part of the system is
disturbed - see Section 2. 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. Don’t work in a garage where a
natural gas-type appliance (such as a
water heater or clothes dryer) with a pilot
light is present. If you spill any fuel on your
skin, rinse it off immediately with soap and
water. When you perform any kind of work
on the fuel system, wear safety glasses,
and have a Class B type fire extinguisher
on hand.

Throttle housing

Check

1 Remove the plenum chamber (see Sec-
tion 4), and verify that the throttle linkage
operates smoothly.
2 If the housing bore and valve are dirty
enough for you to think that this might be the
cause of a fault, seek the advice of a Ford
dealer.  Do not clean the housing (see the
notes in the checking procedure given in
Section 15).

16 Fuel system components -

check and renewal

15 Fuel injection system/engine

management system - check

Fuel and exhaust systems  4•9

4

Renewal

3 Disconnect the battery negative (earth) lead
- see Chapter 5, Section 1.
4 Remove the plenum chamber (see Sec-
tion 4).
5 Disconnect the accelerator cable from the
throttle linkage (see Section 5 or 6, as
appropriate). Where fitted, also disconnect
the cruise control actuator cable (see Chap-
ter 12).
6 Releasing its wire clip, unplug the large
electrical connector (next to the fuel pressure
regulator). Similarly release and unplug the
throttle potentiometer’s electrical connector.
7 Clearly label, then detach, all vacuum hoses
from the throttle housing.
8 Remove the throttle housing mounting
screws (see illustration), then detach the
throttle housing and gasket from the inlet
manifold. Discard the gasket - this must be
renewed whenever it is disturbed.
9 Using a soft brush and carburettor cleaner,
thoroughly clean the exterior of the throttle
housing, then blow out all passages with
compressed air.

Caution: Do not clean the throttle
housing’s bore, the throttle valve,
or the potentiometer, either by
scraping or with a solvent. Just

wipe them over carefully with a clean soft
cloth.
10 Refitting is the reverse of the removal
procedure. Fit a new gasket, and tighten the
housing screws to the specified torque.

Fuel rail and injectors

Check

11 Refer to the procedure in the fuel system
check (see Section 15).

Renewal

Note: For simplicity, and to ensure the
necessary absolute cleanliness on
reassembly, the following procedure
describes the removal of the fuel rail
assembly, complete with the injectors and
pressure regulator, so that the injectors can be
serviced individually on a clean work surface.

It is also possible to remove and refit an

individual injector once the fuel system has
been depressurised and the battery has been
disconnected. If this approach is followed,
read through the complete procedure, and
work as described in the relevant paragraphs,
depending on the amount of preliminary
dismantling required. Be careful not to allow
any dirt to enter the system (see
illustrations).
12 Relieve the residual pressure in the fuel
system (see Section 2), and equalise tank
pressure by removing the fuel filler cap. 

Warning: This procedure will
merely relieve the increased
pressure necessary for the
engine to run - remember that

fuel will still be present in the system
components, and take precautions
accordingly before disconnecting any of
them.
13 Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
14 Remove the plenum chamber (see
Section 4).
15 If the additional clearance is required,
disconnect the accelerator cable from the
throttle linkage (see Section 5 or 6, as
appropriate). Where fitted, also disconnect
the cruise control actuator cable (see Chap-
ter 12).
16 Releasing the wire clips, unplug the four
fuel injector electrical connectors.
17 Disconnect the fuel feed and return lines
at the quick-release couplings next to the
braking system vacuum servo unit, then
unclip the fuel hoses from the inlet manifold;
use rag to soak up any spilt fuel. Note: Do not
disturb the threaded couplings at the fuel rail
unions unless absolutely necessary; these are

sealed at the factory. The quick-release
couplings will suffice for all normal service
operations.
18 Disconnect the crankcase breather hose
from the cylinder head cover union, and the
vacuum hose from the fuel pressure regulator
(see illustration).
19 Unscrew the three bolts securing the fuel
rail, and withdraw the rail, carefully prising it
out of the inlet manifold, and draining any
remaining fuel into a suitable clean container
(see illustrations). Note the seals between
the rail noses and the manifold; these must be
renewed whenever the rail is removed.
20 Clamping the rail carefully in a vice fitted
with soft jaws, unscrew the two bolts securing
each injector, and withdraw the injectors.
Place each in a clean, clearly-labelled storage
container.
21 If you are renewing the injector(s), discard
the old injector, the nose seal and the O-rings.
If you are simply renewing leaking injector O-

4•10 Fuel and exhaust systems

16.8  Undo screws (arrowed) to remove

throttle housing

16.12A  Fuel injectors can be unbolted

(arrowed) . . .

16.12B  . . . and removed individually if

required, but it is better to remove them

with the fuel rail, if servicing is necessary.

O-ring seals (arrowed) must be renewed

whenever injector is removed

16.18  Injector removal - disconnect fuel

lines at quick-release couplings (A), unclip

hoses (B), disconnect vacuum hose from

regulator (C), unplug electrical 

connectors (D) - three of four shown - and

disconnect breather hose from union (E)

16.19A  Unscrew bolts (arrowed) . . .

16.19B  . . . and withdraw fuel rail with

injectors and pressure regulator - renew

nose seals (arrowed) whenever rail is

disturbed

rings, and intend to re-use the same injectors,
remove the old nose seal and O-rings, and
discard them.
22 Further testing of the injector(s) is beyond
the scope of the home mechanic. If you are in
doubt as to the status of any injector(s), it can
be tested at a dealer service department.
23 Refitting is the reverse of the removal
procedure, noting the following points:
(a) Lubricate each nose seal and O-ring with

clean engine oil on installation.

(b) Locate each injector carefully in the fuel

rail recess, ensuring that the locating tab
on the injector head fits into the slot
provided in the rail. Tighten the bolts to
the specified torque.

(c) Fit a new seal to each fuel rail nose, and

ensure the seals are not displaced as the
rail is refitted. Ensure that the fuel rail is
settled fully in the manifold before
tightening the three bolts evenly and to
the torque wrench setting specified.

(d) Fasten the fuel feed and return quick-

release couplings as described in Sec-
tion 3.

(e) Ensure that the breather hose, vacuum

hose and wiring are routed correctly, and
secured on reconnection by any clips or
ties provided.

(f)

On completion, switch the ignition on and
off five times, to activate the fuel pump and
pressurise the system, without cranking
the engine. Check for signs of fuel leaks
around all disturbed unions and joints
before attempting to start the engine.

Fuel pressure regulator

Check

24 Refer to the fuel pump/fuel pressure
check procedure (see Section 8).

Renewal

25 Relieve the residual pressure in the fuel
system (see Section 2), and equalise tank
pressure by removing the fuel filler cap. 

Warning: This procedure will
merely relieve the increased
pressure necessary for the engine
to run - remember that fuel will

still be present in the system components,
and take precautions accordingly before
disconnecting any of them.

26 Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
27 Remove the plenum chamber (see
Section 4).
28 Disconnect the vacuum hose from the
regulator.
29 Unscrew the two regulator retaining bolts,
place a wad of clean rag to soak up any spilt
fuel, and withdraw the regulator (see
illustration).
30 Refitting is the reverse of the removal
procedure, noting the following points:
(a) Renew the regulator sealing O-ring

whenever the regulator is disturbed.
Lubricate the new O-ring with clean
engine oil on installation.

(b) Locate the regulator carefully in the fuel

rail recess, and tighten the bolts to the
specified torque wrench setting.

(c) On completion, switch the ignition on and

off five times, to activate the fuel pump and
pressurise the system, without cranking
the engine. Check for signs of fuel leaks
around all disturbed unions and joints
before attempting to start the engine.

Idle speed control valve

Check

31 Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
32 Raise the front of the vehicle, and support
it securely on axle stands. 

Warning: Do not place any part of
your body under a vehicle when
it’s supported only by a jack!

33 Unplug the valve’s electrical connector
(see illustration).
34 Connect a 12-volt battery across the
valve’s terminals - positive (+) to terminal 37
(the green/yellow wire) and negative (-) to
terminal 21 (the black/yellow). 

Caution: It is essential that the
correct polarity is observed, or
the diode incorporated in the
valve may be damaged.

35 A distinct click should be heard each time
contact is made and broken. If not, measure
the resistance between the terminals. If the
resistance is as specified, the valve is okay
(but there may be a problem with the wiring or
the ECU). If the resistance is not as specified,
renew the valve (see below).

36 Plug in the valve’s electrical connector.

Renewal

37 Disconnect the battery negative (earth)
lead - see Chapter 5, Section 1.
38 Raise the front of the vehicle, and support
it securely on axle stands. 

Warning: Do not place any part of
your body under a vehicle when
it’s supported only by a jack!

39 Unplug the valve’s electrical connector.
40 Unscrew the two retaining bolts, and
withdraw the valve from the inlet manifold
(see illustration).
41 Since the valve’s individual components
are not available separately, and the complete
assembly must be renewed if it is thought to
be faulty, there is nothing to be lost by
attempting to flush out the passages, using
carburettor cleaner or similar solvent. This
won’t take much time or effort, and may well
cure the fault.
42 Refitting is the reverse of the removal
procedure, noting the following points:
(a) Clean the mating surfaces carefully, and

always fit a new gasket whenever the
valve is disturbed.

(b) Tighten the bolts evenly and to the

specified torque wrench setting.

(c) Once the wiring and battery are

reconnected, start the engine and allow it
to idle. When it has reached normal
operating temperature, check that the idle
speed is stable, and that no induction (air)
leaks are evident. Switch on all electrical
loads (headlights, heated rear window,
etc), and check that the idle speed is still
correct.

Fuel and exhaust systems  4•11

4

16.43  Location of idle-increase solenoid

valve (A) and diode (B)

16.29  Disconnect vacuum hose, and

unscrew bolts (arrowed) to withdraw fuel

pressure regulator

16.33  Access to idle speed control valve is

from underneath vehicle - unplug electrical

connector (arrowed) to check valve

16.40  Unscrew bolts (arrowed) to remove

idle speed control valve