open gas tank FIAT UNO 1983 Service Repair Manual

Fault finding - all engines
Note: When investigating starting and uneven running faults, do not be tempted into snap diagnosis. Start from the beginning of the check
procedure and follow it through. It will take less time in the long run. Poor performance from an engine in terms of power and economy is not
normally diagnosed quickly. In any event, the ignition and fuel systems must be checked first before assuming any further investigation needs to
be made.
All engines 1•35
1
Engine fails to turn when starter operated
m mBattery discharged
m mBattery terminals loose or corroded
m mBattery earth to body defective
m mEngine/transmission earth strap broken or loose
m mDisconnected or broken wire in starter circuit
m mIgnition/starter switch defective
m mStarter motor or solenoid defective (see Chapter 9)
m mMajor mechanical failure (seizure) or long disuse (piston rings rusted
to bores)
Engine turns and fails to start
m mBattery discharged
m mBattery terminals loose or corroded
m mBattery or engine earth strap loose
m mStarter motor connections loose
m mOil in engine/transmission too thick
m mStarter motor defective
m mVapour lock in fuel line (in hot conditions or at high altitude)
m mBlocked float chamber needle valve
m mFuel pump filter blocked
m mChoked or blocked carburettor jets
m mFaulty fuel pump
m mFuel tank empty
m mOther fuel system fault (see Chapter 3)
m mShorted or disconnected low tension leads
m mDirty, incorrectly set, or pitted contact breaker points
m mContact breaker point spring earthed or broken
m mFaulty condenser
m mDefective ignition switch
m mFaulty coil
m mDamp or dirty HT leads, distributor cap or plug bodies
m mBroken, loose or disconnected LT leads
m mIgnition leads connected wrong way round
m mOther ignition fault (see Chapter 4)
m mValve timing incorrect (after rebuild)
Engine fires but will not run
m
mInsufficient choke (cold engine)
m mFuel starvation or tank empty
m mIgnition fault (see Chapter 4)
m mOther fuel system fault (see Chapter 3)
Engine stalls and will not restart
m
mToo much choke allowing too rich a mixture to wet plugs
m mFloat damaged or leaking or needle not seating
m mFloat lever incorrectly adjusted
m mIgnition failure - sudden
m mIgnition failure - misfiring precedes total stoppage
m mIgnition failure - in severe rain or after traversing water splash
m mNo petrol in petrol tank
m mPetrol tank breather choked
m mSudden obstruction in carburettor
m mWater in fuel system
Engine slow to warm up
m
mChoke linkage maladjusted
m mAir cleaner temperature control unit defective
m mThermostat stuck open (see Chapter 2)
m mOther fuel system fault (see Chapter 3)
Difficult starting when cold
m
mInsufficient choke
m mFouled or incorrectly gapped spark plugs
m mDamp or dirty HT leads, distributor cap or spark plug bodies
m mDirty or maladjusted contact breaker points
m mOther ignition fault or timing maladjustment (see Chapter 4)
m mFuel system or emission control fault (see Chapter 3)
m mPoor compression (may be due to incorrect valve clearances, burnt
or sticking valves, blown head gasket, worn or damaged pistons,
rings or bores)
m mIncorrect valve timing (after rebuild)
Difficult starting when hot
m
mIncorrect use of manual choke
m mFuel line vapour lock (especially in hot weather or at high altitudes)
m mIncorrect ignition timing
m mOther fuel system or emission control fault (see Chapter 3)
m mPoor compression (see above)
Engine lacks power
m
mIgnition timing incorrect
m mContact breaker points incorrectly gapped
m mIncorrectly set spark plugs
m mDirty contact breaker points
m mDistributor automatic advance and retard mechanisms not
functioning correctly
m mOther ignition system fault (see Chapter 4)
m mAir cleaner choked
m mCarburation too rich or too weak
m mFuel filter blocked
m mAir filter blocked
m mFaulty fuel pump giving top and fuel starvation
m mOther fuel system fault (see Chapter 3)
m mPoor compression
m mValve clearances incorrect
m mCarbon build-up in cylinder head
m mSticking or leaking valves
m mWeak or broken valve springs
m mWorn valve guides or stems
m mWorn pistons and piston rings
m mBurnt out valves
m mBlown cylinder head gasket (accompanied by increase in noise)
m mWorn pistons and piston rings
m mWorn or scored cylinder bore
m mBrakes binding
Engine misfires throughout speed range
m
mDefective or fouled spark plug
m mLoose, cracked or defective HT lead
m mMaladjusted, sticking or burnt valves
m mIgnition timing incorrect
m mBlown head gasket
m mFuel contaminated
m mOther ignition fault (see Chapter 4)
m mOther fuel system fault (see Chapter 3)
Poor engine braking
m
mHigh idle speed
m mOther fuel system fault (see Chapter 3)
m mLow compression

fluid. They are “sealed”. Liquid will get in, but
a thorough clean will be impracticable, and it
will be impossible to get new grease in.
17Check all the parts, get a new gland, two
new grommets, (1116 cc and 1301 cc) and a
new gasket. Scrape all deposits out of the
housing and off the impeller.
18To reassemble, start by inserting the new
grommets (1116 cc and 1301 cc) in the
grooves by each bearing. Fit the circlip to the
shaft, then the shouldered ring, bearings and
spacer. Fit the shaft and bearing assembly
into the cover. Fit the stop screw. Press on
the pulley.
19Fit the new gland (seal), seating it in its
location in the cover. Press the impeller onto
the shaft. The impeller must be put on part
way, and then the housing held in place to see
how far the impeller must go down the shaft
to give the correct clearance, which is 0.8 to
1.3 mm (0.03 to 0.05 in) as shown in Figs. 2.4
and 2.5.
20The impeller clearance can be checked
through the coolant passage in the side of the
pump.
21Refitting is a reversal of the removal
process, but use a new flange gasket and
tension the drivebelt as described in Section 8
(photo).
22Refill the cooling system.
10 Cooling system sensors
1A coolant temperature sender switch is
located in the cylinder head (above No. 1
spark plug) on 903 cc engines and adjacent to
No. 2 spark plug on 1116 cc and 1301 cc
engines.
2The switch operates the coolant
temperature gauge and an excessive
temperature warning lamp.
3On some models, a level sensor is screwed
into the side of the expansion tank. This
sensor consists of a pair of reed switches
within a capsule which are kept closed by the
strong magnetic flux generated by the
hydrostatic force inspired by the action of the
coolant against the float.
4If the coolant level drops then the magneticflux is weakened and the switches open.
5In the event of a fault developing, before
assuming that the cause is the sensor, check
all connecting wiring.
11 Heating and ventilation
system- description
1The heater is centrally mounted under the
facia and is of fresh air type.2Air is drawn in through the grille at the base
of the windscreen. It then passes through the
coolant heated matrix when it can then be
distributed through selective outlets
according to the setting of the control levers.
3A booster fan is provided for use when the
car is stationary or is travelling too slowly to
provide sufficient air ram effect.
4Fresh air outlets are provided at each end
and centrally on the facia panel.
12 Heater unit-
removal and refitting
1
1Drain the cooling system.
2Disconnect the heater hoses at the engine
compartment rear bulkhead.
3Working within the car under the facia
panel, disconnect the leads from the
heater blower by pulling the connecting plug
apart.
4If a radio is fitted, disconnect the
aerial, earth, speaker and power leads from
it.
Cooling and heating systems 2•5
Fig. 2.6 Checking impeller clearance
(Sec 9)9.21 Fitting coolant pump (1116 cc engine)
Fig. 2.7 Heater and ventilation system (Sec 11)
A Fresh air inlet flap
B Air distribution flap
C Coolant valveD Blower
E MatrixF Control levers
G Footwell air duct
2

Coolant pump -
removal and refitting#
11The coolant pump is located on the
crankshaft pulley end of the engine and is
driven by the timing belt.
12The pump cannot be repaired and must
be regarded as disposable.
13Drain the cooling system.
14Remove the timing belt cover and then set
No. 1 piston to TDC. To achieve this, turn the
crankshaft pulley bolt until the camshaft
sprocket timing mark is aligned with the one
on the cylinder head.
15Release the belt tensioner and slip the
timing belt off the camshaft and coolant pump
sprockets.
16Unbolt and remove the coolant pump and
clean the mounting face of all old gasket
material.
17Apply a continuous bead of RTV silicone
sealant (instant gasket) to the mounting face
of the coolant pump and bolt it into position
(photos).
18Check that the camshaft sprocket and the
crankshaft have not been moved and fit the
timing belt to the camshaft and coolant pump
sprockets. The pump sprocket does not
require setting in any particular position
before connecting the timing belt.
19Tension the belt as described in Sec-
tion 5B of this Chapter.
20Fit the timing belt cover.
21After allowing one hour for the gasket
material to cure, refill and bleed the cooling
system.
PART B:
1301 CC TURBO IE ENGINE
Description
1The cooling system on this model has flow
and return connections to the turbocharger,
and is an essential means of cooling the
turbocharger.
2The radiator cooling fan is of two-speed
type, being controlled by a two-stage
thermostatic switch screwed into the radiator
side tank.
3According to the coolant temperature level,
the fan speed is regulated to provide the most
effective cooling.
4The remote cooling system expansion tank
is mounted in the left-hand rear corner of the
engine compartment (photo).
PART C:
1372 CC IE AND 1372 CC
TURBO IE ENGINES
Description
1The cooling system layout and components
for the 1372 cc engines is shown in
Figs. 13.29 and 13.30.
2The system on each engine operates in
essentially the same manner as that
described for the other models in Chapter 2,
but the location of components and the
coolant hose routings differ according to
model. The cooling system expansion tank
location differs according to model, being
either located on the side of the radiator ormounted separately on the side of the inner
wing panel.
3On Turbo models, the cooling system also
assists in cooling the turbocharger.
Maintenance
4The maintenance procedures are
essentially the same as those described for
the other models in Chapter 2.
Cooling system - draining,
flushing and refillingÁ
Warning: Wait until the engine is
cold before starting this
procedure. Do not allow
antifreeze to come into contact
with your skin or painted surfaces of the
vehicle. Rinse off spills immediately with
plenty of water. Never leave antifreeze
lying around in an open container or in a
puddle in the driveway or on the garage
floor. Children and pets are attracted by its
sweet smell. Antifreeze is fatal if ingested.
5Disconnect the battery negative lead.
6Working inside the vehicle, turn the heater
temperature control knob fully to the right,
which will fully open the heater coolant valve.
7With the expansion tank cap removed,
place a suitable container beneath the
radiator bottom hose.
8Loosen the clip and ease the bottom hose
away from the radiator outlet (photo). Allow
the coolant to drain into the container.
9Reposition the container under the front of
the cylinder block, and unscrew the cylinder
block drain plug (photo). Allow the coolant to
drain into the container.
Supplement: Revisions and information on later models 13•55
8A.17B Tightening the coolant pump bolts8A.17A Fitting the coolant pump to the
999 cc engineFig. 13.28 Sectional view of the coolant
pump on the 999 and 1108 cc engines
(Sec 8A)
8C.9 Cylinder block drain plug8C.8 Bottom hose connection to the
radiator8B.4 Topping up the expansion tank with
antifreeze on the 1301 cc engine
13

10Apply suitable sealant to the threads of
the drain plug, then refit and tighten the plug.
11Dispose of the drained coolant safely, or
keep it in a covered container if it is to be
re-used.
12If required, the system can be flushed
through as described in Section 2 of Chap-
ter 2.
13Before attempting to refill the cooling
system, make sure that all hoses have been
reconnected, that the hoses and clips are in
good condition, and that the clips are tight.
Also ensure that the cylinder block drain plug
has been refitted and tightened. Note that an
antifreeze mixture must be used all year round
to prevent corrosion of the engine
components - refer to Section 3, Chapter 2.
14Open the bleed screw in the top of the
expansion tank (photo).
15Remove the expansion tank cap, and fill
the system by slowly pouring the coolant into
the expansion tank to prevent air locks from
forming.
16Top up the coolant until liquid free from air
bubbles emerges from the radiator bleed
screw orifice, then close the bleed screw.
17Continue topping up until the coolant
reaches the Maximum mark on the expansion
tank.
18Start the engine and run it until it reaches
normal operating temperature, then stop the
engine and allow it to cool. Normal operating
temperature is reached when the cooling fancuts into operation. Feel the radiator top hose
to ensure that it is hot. If cool, it indicates an
air lock in the system.
19Check for leaks, particularly around
disturbed components. Check the coolant
level in the expansion tank, and top up if
necessary. Note that the system must be cold
before an accurate level is indicated. There is
a risk of scalding if the expansion tank cap is
removed whilst the system is hot.
Radiator (and cooling fan)
- removal and refitting Á
20Disconnect the battery negative lead.
21Detach the wiring connectors from the
cooling fan and the fan switch located in the
radiator (photos).
22If preferred, the cooling fan unit can be
removed separately from the radiator, by
undoing the attachment bolts and carefully
withdrawing the unit upwards from the
vehicle. Take care not to damage the radiator
core as it is lifted clear (photo).
23Drain the cooling system as described
earlier in this part of the Section, but note that
it will not be necessary to remove the cylinder
block drain plug.
24Undo the retaining screws and remove
the front grille panel.
25Loosen off the retaining clips and detach
the upper coolant hose and the expansion
hose from the radiator.26Note their direction of fitting, then prise
free the radiator retaining clips. Carefully lift
the radiator from the car.
27Refitting is a reversal of the removal
procedure. Ensure that as the radiator is
lowered into position, it engages in the two
rubber location grommets.
28With the radiator (and cooling fan) refitted,
top up the cooling system as described earlier
in this Section (photo).
Thermostat -
removal and refitting Á
Note: A new thermostat cover gasket must be
used on refitting.
29Drain the cooling system as described
earlier in this Section, but note that there is no
need to drain the cylinder block.
30Disconnect the coolant hoses from the
thermostat cover (situated at the gearbox end
of the cylinder head).
31Unscrew the two thermostat cover
securing bolts, noting that the left-hand bolt
may also secure the HT lead bracket, and
remove the thermostat/cover assembly.
Recover the gasket (photo).
32If faulty, the thermostat must be renewed
complete with the housing as an assembly.
33If desired the thermostat can be tested as
described in Chapter 2.
34Refitting is a reversal of removal, bearing
in mind the following points.
Supplement: Revisions and information on later models 13•57
8C.21B Cooling fan switch wiring
connector8C.21A Cooling fan and wiring connector8C.14 Bleed screw location on top of the
expansion tank (arrowed)
8C.31 Thermostat unit removal on the
1372 cc ie engine (distributor removed for
clarity)8C.28 Topping up the radiator coolant level
on the 1372 cc ie engine. Note orientation
of radiator retaining clip (arrowed)8C.22 Cooling fan to radiator securing bolt
13

8The air cleaner on the 1116 cc and
1299/1301 cc engine is of circular type.
Access to the element is obtained by
extracting the three cover nuts and lifting off
the lid (photos).9The air cleaner casing can be removed after
unscrewing the four nuts which hold it to the
carburettor and the single nut on the camshaft
cover bracket. As the casing is withdrawn,
disconnect the hoses from it (photos).10The thermostatically-controlled cold air
flap opener is similar to that described in
paragraph 7.
11The air cleaner on the 1372 cc ie engine is
of rectangular shape. The element can be
removed after releasing the spring clips at the
front of the unit, followed by the two screws
from its top face. The air cleaner end cover
can then be withdrawn and the element
removed. The air cleaner unit on the 1372 cc
Turbo ie engine is located in the front
right-hand corner of the engine compartment.
Prise free the four clips to release the top
cover and expose the element.
Fuel pump (999 and 1108 cc
carburettor models) -
description, removal
and refitting
Á
12The fuel pump is mechanically-operated
via a pushrod which is in contact with an
eccentric cam on the camshaft. The pump is
of sealed, disposable type - no repair or
cleaning being possible.
13To remove the pump, disconnect the
flexible hoses and unbolt the pump from the
cylinder head. Retain the pushrod and the
insulator block.
14Refitting is a reversal of removal, use new
gaskets, one on each side of the insulator
block.
Fuel tank (999 and 1108 cc
engines)
15In conjunction with the plastic type fuel
tank, the breather and fuel level transmitter
unit have been modified as shown in
Fig. 13.35.
Supplement: Revisions and information on later models 13•61
9A.9A Circular type air cleaner fixing nuts9A.9B Circular type air cleaner nut on the
camshaft cover (arrowed)
9A.8B Circular type air cleaner element9A.8A Air cleaner on the 1116 cc, 1299 cc
and 1301 cc models
Fig. 13.35 Fuel tank and supply circuit on the 999 and 1108 cc engines (Sec 9A)
1 Carburettor 2 Fuel pump 3 Fuel return pipe 4 Fuel feed pipe 5 Tank vent valve 6 Fuel level sender unit
13

adjustments described in this sub-Section,
however, will require removal of the
carburettor.
39Disconnect the short, curved diaphragm
hose from the top cover.
40Extract the top cover screws, lift the cover
from the carburettor body, and rotate it in
order to release the cranked choke control
rod from its key hole (photo). Mop out the fuel
and clean the jets.
41Check the jet sizes and other components
against those listed in the Specifications, in
case a previous owner has substituted
incorrect components (photo).
42Overhaul procedures are generally as
given in Chapter 3, Section 14 for the Weber
30/32 DMTR, but use the Specifications listed
in this Chapter. Additional overhaul
procedures are given here.
Fuel inlet needle valve
43If a high float level causing flooding of the
carburettor has been evident, first check that
the inlet valve housing is tight, and its washer
is sealing satisfactorily. A leak here will cause
fuel to bypass the inlet valve.
44If the needle valve is to be renewed,
remove it in the following way.
45Access to the fuel inlet needle valve is
obtained by carefully tapping out the float arm
pivot pin. Take care, the pivot pin pillars are
very brittle (photo).
46Unscrew the fuel inlet valve body and
remove the valve and washer.47When refitting the new valve, always use a
new sealing washer.
Float stroke (travel) - see Fig. 3.10
48The float stroke should be between 42.5
and 43.5 mm when measured from the top
cover gasket. Adjust if necessary by bending
the tab on the end of the arm.
Accelerator pump
49Adjustment of the accelerator pump is
very rarely required, but if performance is
suspect, carry out the following operations.
50Fill the carburettor float chamber and then
operate the throttle valve plate lever several
times to prime the pump.
51Position a test tube under the accelerator
pump jet and give ten full strokes of the
throttle lever, pausing between each stroke to
allow fuel to finish dripping.
52The total volume of fuel collected should
be as specified. Adjust the nut on the pump
control if necessary to increase or decrease
the volume of fuel ejected.
General
53When the stage is reached where the
valve plate spindle bushes have worn, then
the carburettor should be renewed complete.
54When reassembling the carburettor, use
new gaskets which can be obtained in a repair
pack.
Carburettor (Weber 32 ICEV
61/250 and DMTE 30/32,
DMTE 30/150) - general
55These carburettor types are fitted to later
models according to engine type. They are
similar in structure and operation to their
equivalents described in Chapter 3. Reference
can therefore be made to that Chapter for the
description and any operations concerning
them, but refer to Section 2 of this Chapter for
their specifications.
Carburettor (Solex
C 30/32-CIC 8) - description
56This carburettor is fitted as an alternative
to the Weber unit on 1116 cc models
produced for certain markets. The removal,
refitting and overhaul procedures are
essentially the same as described earlier for
the Weber carburettors.
PART C:
BOSCH LE2-JETRONIC
FUEL INJECTION SYSTEM
Description
Warning: Refer to the beginning
of this Section before starting
any work.
1The Bosch LE2-Jetronic fuel injection
system, fitted to the 1301 cc Turbo ie model,
is an electronically controlled multi-point
injection (MPi) system.
2The fuel injectors are fed at constant
pressure in relation to inlet manifold vacuum
pressure.
3The system electronic control unit (ECU)
actuates the injectors for variable duration,
and so supplies the precise volume of fuel
required for any given engine speed and load
condition.
4The ECU also monitors the air induction, air
temperature, coolant temperature and throttle
opening as additional parameters to compute
the required opening of the fuel injectors,
giving maximum power with fuel economy.
Fuel supply system
5The fuel supply system consists of an
electric pump and primary filter, located
adjacent to the fuel tank. A fuel pressure peak
damper is located next to the pump (photo).
6Fuel is then pumped through a filter to the
fuel rail and injectors. The injectors are of the
13•66 Supplement: Revisions and information on later models
9C.5 Electric fuel pump/filter/pressure
damper assembly location on a 1301 cc
Turbo ie model
9B.41 Jets on the Weber 30/32 DMTE
carburettor (top cover removed)
9B.45 Float pivot arrangement and needle
valve on the Weber 30/32 DMTE
carburettor
9B.40 Unscrewing a top cover screw from
the Weber 30/32 DMTE carburettor9B.37F Unscrewing a carburettor fixing nut

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 its
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 its 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 its efficiency; in
severe cases the element will overheat.
h) Remember that the catalytic converter
operates at very high temperatures 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 working on the exhaust system,
ensure that the converter is well clear of
any jacks or other lifting gear used to raise
the car and do not drive the car over
rough ground road humps, etc., in such a
way as to ground the exhaust system.
j) In some cases, particularly when the car is
new and/or is used for stop/start driving, a
sulphurous smell (like that of rotten eggs)
may be noticed from the exhaust. This is
common to many catalytic
converter-equipped cars and seems to be
due to the small amount of sulphur found
in some petrols reacting with hydrogen in
the exhaust to produce hydrogen sulphide
(H
2S) gas; while this gas is toxic, it is not
produced in sufficient amounts to be a
problem. Once the car has covered a few
thousand miles the problem should
disappear - in the meanwhile a change of
driving style or of the brand of petrol used
may effect a solution.
k) The catalytic converter, used on a
well-maintained and well driven car,
should last for at least 50 000 miles
(80 000 km) or five years - from this point
on, careful checks should be made at all
specified service intervals on the CO level
to ensure that the converter is still
operating efficiently - if the converter is no
longer effective it must be renewed.
Fuel evaporation control system
- general
76As mentioned earlier, fuel evaporation is
contained within the system. In high outdoor
temperatures, when the vehicle is parked for a
period of time, the fuel in the tank evaporates,
building up pressure. When the pressure builds
up to a predetermined level a vent valve opens
to allow the vapours to pass on to and absorbed
by a carbon filter. However, if extreme pressure
or vacuum should build up, a two way safety
valve opens to allow external venting.
77If the safety valve needs replacing, note
that it must be fitted correctly. The black end
should be connected to the fuel tank and the
blue to the carbon filter.
78The vapours in the carbon filter are
flushed by warm air passing through the filter
on to a ECU controlled vapour cut-off
solenoid.
79The cut-off solenoid is closed when
starting the engine and opens to allow
vapours to be drawn into the inlet manifold,
through a second solenoid. If the cut-off
solenoid needs replacing ensure that the
black arrow on the casing is pointing towards
the inlet manifold.
80The second solenoid, known as an Elbi
solenoid, is closed when the engine is turned
off, thus preventing engine run-on. The side
facing connection is for the inlet manifold
pipe.
PART E:
BOSCH L3.1/2 JETRONIC
FUEL INJECTION SYSTEMS
Warning: Refer to the beginning
of this Section before starting
any work.
Description
1A Bosch L3.1 (or L3.2, as fitted from 1992)
Jetronic fuel injection system is fitted to the
1372 cc Turbo ie engine. The system circuit
and main component locations are shown in
Figs. 13.48 and 13.49.
2The L3.1/2 Jetronic system is a multi-point
fuel injection (MPi) system. It operates in a
similar manner to that of the LE2-Jetronic
system fitted to the 1301 cc Turbo ie engine
described in Part C of this Section. The L3.1/2
system is more sophisticated and has the
ability to provide reasonably efficient engine
operation when system sensors malfunction.
As with the LE2 system, the fuel and air
supply mixture circuits are regulated in
accordance with the electronic control unit
(ECU), but on the L3.1/2 system the control
unit is attached to the upper part of the
airflow meter.
3The ECU analyses the information passed
to it from the system sensors. These signals
are then processed and the air/fuel mixture is
constantly adjusted as required to provide the
13•78 Supplement: Revisions and information on later models
Fig. 13.48 Bosch L3.1 Jetronic fuel injection system - 1372 cc Turbo ie engine (Sec 9E)
1 ECU
1A Diagnostic socket
2 Injection system relay and
fuel pump relay
3 Ignition switch
4 Battery
5 Fuel tank
6 Fuel pump
6A Primary fuel filter7 Coolant temperature
sensor
8 Intake air cooling radiator
(intercooler)
9 Air cleaner
10 Supplementary air valve
11 Throttle position switch
11A Throttle housing
12 Airflow meter12A Intake air temperature
sensor
13 Fuel pressure regulator
14 Fuel rail (to injectors)
15 Secondary fuel filter
16 Injectors
17 Injector cooling fan
18 Thermostatic switch (to
engage injector cooling fan)