oil filter FORD SIERRA 1991 2.G Fuel And Exhaust Systems Fuel Injection Workshop Manual

manual mixture adjustment is possible.
On models with a catalytic converter, an
evaporative emission control (EVAP) system is
fitted. This prevents the release of fuel vapour
into the atmosphere. With the ignition
switched off, vapours from the fuel tank are
fed to a carbon canister, where they are
absorbed. When the engine is started, the
EEC IV module opens a purge solenoid valve,
and the fuel vapours are fed into the inlet
manifold and mixed with fresh air. This cleans
the carbon filter. A blow-back valve prevents
inlet air being forced back into the fuel tank.
A fuel pump inertia switch is fitted. This
switch breaks the electrical circuit to the fuel
pump in the event of an accident or similar
impact, cutting off the fuel supply to the engine.
A “limited operation strategy” (LOS) means
that the vehicle will still be driveable, albeit at
reduced power and efficiency, in the event of
a failure in the EEC IV module or its sensors.
1.6 and 1.8 litre (R6A type) CVH models
The fuel injection system fitted to these
models is under the overall control of an EEC
IV engine management system which also
controls the ignition timing.
Fuel is supplied from the rear-mounted fuel
tank by an electric fuel pump which is integral
with the fuel level sender unit mounted inside
the fuel tank. Fuel passes via a fuel filter to the
Central Fuel Injection (CFI) unit. A fuel
pressure regulator, mounted on the CFI unit,
maintains a constant fuel pressure to the fuel
injector. Excess fuel is returned from the
regulator to the tank.
The CFI unit, resembling a carburettor,
houses the throttle valve, throttle valve control
motor, throttle position sensor, air charge
temperature sensor, fuel injector, and
pressure regulator.
The duration of the electrical pulse supplied
to the fuel injector determines the quantity of
fuel injected, and pulse duration is computed
by the EEC IV module on the basis of
information received from the various sensors.
The fuel injector receives a pulse twice per
crankshaft revolution under normal operating
conditions, and once per crankshaft
revolution under engine idle conditions. A
ballast resistor is used in the fuel injector
control circuit on 1.6 litre engines.
Inlet air passes through the air cleaner into
the CFI unit. The volume of air entering the
engine is calculated by the EEC IV module from
information supplied by various sensors. These
sensors include the air charge temperature
sensor and throttle position sensor, mounted in
the CFI unit; a crankshaft speed/position
sensor which supplies information on engine
speed; and a manifold absolute pressure (MAP)
sensor which measures the pressure of the air
entering the engine.
Additional sensors inform the EEC IV module
of engine coolant temperature, and vehicle
speed (from a gearbox-mounted sensor).
An exhaust gas oxygen (HEGO) sensor
enables the EEC IV module to control the
fuel/air mixture to suit the operating
parameters of the catalytic converter. No
manual mixture adjustment is possible.
Idle speed is controlled by a throttle valvecontrol motor, which controls the position of
the throttle valve under conditions of idling,
deceleration/part-throttle, and engine start-up
and shut-down.
On 1.6 litre engines, a pulse-air system is
fitted to reduce the exhaust gas emissions
during engine warm-up. The system is con-
trolled by a vacuum-operated valve, which is
operated by the EEC IV module via a solenoid.
The system introduces air into the exhaust
manifold to increase the exhaust gas
temperature, which oxidises more of the
pollutants, and brings the catalyst up to
working temperature more quickly. The
system operates until the catalyst reaches
operating temperature, when the control
solenoid shuts off the system.
On 1.8 litre engines, an exhaust gas
recirculation (EGR) system is used to
recirculate a small amount of exhaust gas into
the inlet manifold. This process lowers the
combustion temperature, resulting in a
reduction of NOx (oxides of nitrogen)
emissions. The EGR system is controlled by
the EEC IV module in conjunction with an
Electronic Pressure Transducer (EPT) and an
Electronic Vacuum Regulator (EVR).
On certain models, an evaporative emission
control system may be fitted. This prevents
the release of fuel vapour into the
atmosphere. With the ignition switched off,
vapours from the fuel tank are fed to a carbon
canister, where they are absorbed. When the
engine is started the EEC IV module opens a
purge solenoid valve, and the fuel vapours are
fed into the inlet manifold and mixed with
fresh air. This cleans the carbon filter. A blow-
back valve prevents inlet air being forced
back into the fuel tank.
A fuel pump inertia switch is fitted. This
switch breaks the electrical circuit to the fuel
pump in the event of an accident or similar
impact cutting off the fuel supply to the engine.
A “limited operation strategy” (LOS) means
that the vehicle will still be driveable, albeit at
reduced power and efficiency, in the event of
a failure in the EEC IV module or its sensors.
Precautions
Many of the procedures in this Chapter
require the removal of fuel lines and
connections which may result in some fuel
spillage. Before carrying out any operation on
the fuel system refer to the precautions given
in “Safety first!” at the beginning of this
Manual and follow them implicitly. Petrol is a
highly dangerous and volatile liquid and the
precautions necessary when handling it
cannot be overstressed.
Residual pressure will remain in the fuel
lines long after the vehicle was last used,
therefore extra care must be taken when
disconnecting a fuel line hose. Loosen any
fuel hose slowly to avoid a sudden release of
pressure which may cause fuel spray. As an
added precaution place a rag over each union
as it is disconnected to catch any fuel which is
forcibly expelled.
Certain adjustment points in the fuel system
(and elsewhere) are protected by
“tamperproof” caps, plugs or seals. The
purpose of such tamperproofing is todiscourage, and to detent, adjustment by
unqualified operators.
In some EEC countries (though not yet in
the UK) it is an offence to drive a vehicle with
missing or broken tamperproof seals. Before
disturbing a tamperproof seal, satisfy yourself
that you will not be breaking local or national
anti-pollution regulations by doing so. Fit a
new seal when adjustment is complete when
this is required by law.
Do not break tamperproof seals on a
vehicle which is still under warranty.
Catalytic converter - precautions
The catalytic converter is a reliable and simple
device which needs no maintenance in itself,
but there are some facts of which an owner
should be aware if the converter is to function
properly for the full service life.
a)DO NOT use leaded petrol in a car
equipped with a catalytic converter the
lead will coat the precious metals,
reducing their converting efficiency and
will eventually destroy the converter.
b)Always keep the ignition and fuel systems
well-maintained in accordance with the
manufacturers schedule, ensure that the
air cleaner filter element, the fuel filter
(where fitted) and the spark plugs are
renewed at the correct interval if the inlet
air/fuel mixture is allowed to become too
rich due to neglect, the unburned surplus
will enter and burn in thecatalytic
converter, overheating the element and
eventually destroying the converter.
c)If the engine develops a misfire, do not
drive the car at all (or at least as little as
possible) until the fault is cured - the
misfire will allow unburned fuel to enter
the converter, which will result in
overheating, as noted above.
d)DO NOT push- or tow-start the car - this
will soak the catalytic converter in
unburned fuel, causing it to overheat when
the engine does start - see b) above.
e)DO NOT switch off the ignition at high
engine speeds - if the ignition is switched
off at anything above idle speed,
unburned fuel will enter the (very hot)
catalytic converter, with the possible risk
of igniting on the element and damaging
the converter.
f)DO NOT use fuel or engine oil additives -
these may contain substances harmful to
the catalytic converter.
g)DO NOT continue to use the car if the
engine burns oil to the extent of leaving a
visible trail of blue smoke - the unburned
carbon deposits will clog the converter
passages and reduce the efficiency; in
severe cases the element will overheat.
h)Remember that the catalytic converter
operates at very high temperatures - hence
the heat shields on the car’s underbody
and the casing will become hot enough to
ignite combustible materials which brush
against it - DO NOT, therefore, park the car
in dry undergrowth, over long grass or
piles of dead leaves.
i)Remember that the catalytic converter is
FRAGILE, do not strike it with tools during
servicing work, take great care when
Fuel and exhaust systems - fuel injection 4B•3
4B

5The system will remain depressurised until
the fuel pump is primed prior to starting the
engine. Remove the container or cloth, as
applicable, on completion.
Refer to Chapter 1, Section 41.
2.0 litre SOHC models
1Disconnect the battery negative lead.
2Slowly loosen the fuel feed union to relieve
the pressure in the fuel lines.
3Disconnect the fuel feed and return lines.
Be prepared for petrol spillage.
4Disconnect the vacuum pipe from the top
of the pressure regulator.
5Unscrew the securing nut from the base of
the pressure regulator and withdraw the unit
(see illustration).
6Refitting is a reversal of removal, but if the
fuel return line was originally secured with a
crimped type clip, discard this and use a new
worm drive clip.
7On completion check the fuel line
connections for leaks. Pressurise the system by
switching the ignition on and off several times.
2.0 litre DOHC models
Note: A new pressure regulator seal will be
required on refitting.
8Disconnect the battery negative lead.
9Slowly loosen the fuel rail fuel feed union to
relieve the pressure in the system (see
illustration). Be prepared for fuel spillage,
and take adequate fire precautions.
10Disconnect the fuel return hose from the
pressure regulator (see illustration). Again,
be prepared for fuel spillage.
11Disconnect the vacuum pipe from the top
of the pressure regulator.
12Unscrew the two securing bolts, and
withdraw the regulator from the fuel rail.
Recover the seal.13Fit a new seal to the regulator, and
lubricate with clean engine oil.
14Fit both the securing bolts to the
regulator, then position the regulator on the
fuel rail, and tighten the securing bolts.
15Further refitting is a reversal of removal. If
the fuel return line was originally secured with
a crimped-type clip, discard this, and use a
new worm-drive clip.
16On completion, pressurise the system by
switching the ignition on and off several times,
and check the fuel line connections for leaks.
1.6 and 1.8 litre (R6A type) CVH
models
Note:On completion of refitting, the fuel
system pressure should be checked by a Ford
dealer at the earliest opportunity.
1.6 litre
17Remove the CFI unit.
18Remove the four screws securing the
regulator housing to the CFI unit, then
carefully lift off the housing and recover the
ball, cup, large spring, diaphragm, valve, and
small spring, noting the position and
orientation of all components (see
illustration). Do not attempt to prise the plug
from the regulator housing, or adjust the Allen
screw (if no plug is fitted); this will alter the fuel
system pressure.
19Check all components, and renew any
faulty items as necessary.
20Commence reassembly by supporting the
CFI unit on its side, so that the regulator
components can be fitted from above.
6Fuel pressure regulator -
removal and refitting
5Fuel filter - renewal
Fuel and exhaust systems - fuel injection 4B•5
4B
6.9 Fuel rail fuel feed union (arrowed)
6.10 Disconnecting the fuel return hose
(arrowed) from the pressure regulator
6.5 Withdrawing the fuel pressure
regulator
6.18 Exploded view of Central Fuel Injection (CFI) unit
1.6 litre CVH engine application shown - 1.8 litre similar
1 Fuel injector assembly
2 Fuel pressure regulator
components
3 Fuel inlet connector
4 Air charge temperature
(ACT) sensor
5 Throttle valve control
motor
6 Throttle position sensor
7 Fuel injector wiring
Caution: Refer to the
precautions in Section 1 before
proceeding.