1983 FIAT UNO engine overheat

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)

protective shield to gain access to the pump
which is located forward of the fuel tank.
60Disconnect the fuel hoses and the wiring
connector, release the retaining clamp and
withdraw the pump unit.
Refitting all components
61Refitting of all components is a reversal of
the removal procedure, but note the following
specific points.
62Ensure that all components are clean prior
to refitting and where applicable, use new
seals and gaskets. Ensure that all connectionsare securely and correctly made.
63Do not reconnect the battery until all the
refitting procedures are complete.
64When the engine is restarted, check
around the fuel injection system for any signs
of leakage from the fuel supply and return
components.
Lambda sensor - general
65The sensor is screwed into the exhaust in
front of the catalytic converter.
66A faulty sensor can damage the converter,
therefore it must be checked regularly (see
Maintenance schedule, Section 3) by a dealer
using special equipment.
67Use of leaded fuel will also damage this
sensor, as well the converter.
PART F:
TURBOCHARGER SYSTEM
Description
1A turbocharger is fitted to certain 1301 and
1372 cc ie engines. The accompanying
photographs are all taken from a 1301 cc
engine, but the system is much the same for
both engine types.
2The turbocharger is basically a shaft with an
exhaust gas-driven turbine at one end, and a
compressor located at the other end which
draws in outside air and forces it into the inlet
manifold. By compressing the incoming air, a
larger charge can be let into each cylinder,
and greater power output is achieved than
with normal aspiration.3Lubrication of the turbocharger shaft
bearings is provided by pressurised engine
oil, and the unit is cooled by the coolant from
the engine cooling system.
4A wastegate valve is incorporated in the
turbocharger to divert excessive exhaust gas
pressure from the turbine into the exhaust
pipe at a predetermined pressure level.
5A maximum air pressure switch is located in
the inlet manifold. Its purpose is to cut the
ignition system off when the turbocharger
system pressure continues to increase
beyond 0.86 bars (12.5 lbf/in
2). This would
otherwise damage the engine, due to high
combustion temperatures and pressures
(photo).
6An intercooler (heat exchanger) is located
between the turbocharger and the inlet
manifold. Its function is to cool the inlet
charge, thus increasing its density, to provide
greater power output.
7A mechanical bypass valve is located
between the low-pressure pipe (downstream)
and the high-pressure pipe (upstream), which
reduces the inherent noise from the
turbocharger when the accelerator pedal is
released (photo).
8None of the components of the
turbocharger system can be repaired and
parts are not available. Any fault will therefore
mean that the turbocharger or associated
assemblies will have to be renewed complete.
Precautions
9The following precautions should be
observed when using a turbocharged vehicle.
a) Never operate the engine without the air
cleaner fitted.
b) Never switch off the engine before its
speed has dropped to idling. If the car
has been driven hard, allow it to idle for a
few minutes before switching off. Failure
to observe these recommendations can
cause damage to the turbocharger due to
lack of lubrication.
10Always keep the fuel injection system
well-maintained and tuned. Operating on a
weak mixture can cause overheating of the
turbocharger.
Turbocharger
(1301 cc ie engine) -
removal and refitting
Á
11Disconnect and remove the airflow meter
as described in Section 9C.
12Disconnect the spiral-wound hose from
the fuel injector cooling duct.
13Remove the turbocharger air hoses from
within the left-hand side of the engine
compartment. Note particularly their routing.
14Remove the throttle housing/inlet
manifold as described in Section 9C, also the
fuel rail, injectors and inlet manifold branch
pipe stubs. Remove the alternator heat shield
(photo).
15Remove the exhaust heat shield.
16Unscrew the turbocharger-to-exhaust
pipe flange nuts (photos).
13•82 Supplement: Revisions and information on later models
9F.16A Turbocharger-to-exhaust flange
nut (arrowed)9F.14 Alternator heat shield
9F.7 Bypass valve9F.5 Maximum air pressure switch
(arrowed)
Fig. 13.63 Fuel pump and sender unit
location on the 1372 cc Turbo ie engine
(Sec 9E)
1 Fuel level gauge sender connector
2 Fuel pump connector
3 Fuel return hose
4 Fuel supply hose

Wiring diagrams 14•1
14
Component key for wiring diagrams 1 to 29
Note: Not all the items listed will be fitted to all models
No Description
00200 Alternator with built-in regulator
00500 Battery
01001 Starter motor
01202 Rear front electric window motor
01203 Left front electric window motor
01206 Windscreen wiper motor
01207 Rear screen wiper motor
01252 Right front door locking motor
01253 Left front door locking motor
01254 Right rear door locking motor
01255 Left rear door locking motor
01400 Windscreen washer pump
01401 Rear screen washer pump
01420 Electric fuel pump
01500 Engine cooling fan
01502 Injector cooling fan
01504 Ventilation fan
02001 Engine cut-out solenoid on injection pump
02010 Fuel injector
02011 Fuel injector
02012 Fuel injector
02013 Fuel injector
02015 Supplementary air valve
02210 Accelerator pump outlet cut-out solenoid on
carburettor
02215 Supplementary air valve
02400 Ignition coil
02405 Ignition coil with electronic control unit
02490 Static advance ignition control unit
02492 Microplex ignition system control unit
03000 Insufficient engine oil pressure switch
03002 Right front door ajar switch
03003 Left front door ajar switch
03004 Right rear door ajar switch
03005 Left rear door ajar switch
03006 Handbrake ‘on’ warning switch
03007 Brake stop-lamp switch
03008 Reversing light switch
03028 Radiator thermostatic switch
03029 Coolant overheating warning light thermostatic switch
03034 Injector cooling fan thermostatic switch
03035 Accelerator pump outlet cut-out solenoid thermostatic
switch
03036 Radiator thermostatic switch with two operating ranges
03053 Map reading light switch
03059 Foglamps switch
03060 Rear foglamp switch
03110 Heated rear screen switch
03114 Ventilation fan switch
03123 Air pressure switch
03142 Choke warning light switch
03144 Reset switch
03145 Display switch
03305 Right front door open light push button
03306 Left front door open light push button No Description
03319 Horn push button
03500 Ignition switch
03505 Butterfly valve cut-off switch
03506 Throttle position switch
03530 Right front electric window switch
03531 Left front electric window switch
03546 Rear screen wash/wipe switch
03550 Hazard warning lights switch
04010 Steering column switch unit, direction indicators
04022 Steering column switch unit, headlamps, main beam
and dipped, side lights
04032 Steering column switch unit, windscreen wash/wipe
04214 Fuel injection system control relay
04215 Antiskid system failure relay
04225 Radiator fan 2nd speed engagement relay feed
04241 Foglamps relay feed
04260 Electric windows motor relay feed
04283 Antiskid system relay
04291 Horn relay feed
04292 Heated rear screen relay feed
04441 Dim-dip cut-out 04600 Ignition distributor
04700 Coolant temperature sender unit
04701 Electronic injection coolant temperature sender unit
04720 Oil pressure sender unit
05008 Right headlamp, main beam and dipped with side light
05009 Left headlamp, main beam and dipped with side light
05013 Abnormal fuel consumption sensor
05015 Right foglamp
05016 Left foglamp
05410 Right front direction indicator
05411 Left front direction indicator
05412 Right front side direction indicator
05413 Left front side direction indicator
05640 Rear number plate lamp
05690 Right rear light cluster, sidelight, direction indicator,
brake light, rear foglamp
05691 Left rear light cluster; side light, direction indicator,
brake light, rear foglamp
06000 Centre courtesy light
06026 Map reading light
06076 Ideogram fibre optic light
06080 Heater controls light
06084 Instrument panel light
06300 Sidelights warning light
06305 Main beam headlamps warning light
06310 Rear foglamps warning light
06311 Foglamps warning light
06315 Hazard warning lights warning light
06320 Direction indicators warning light
06335 Insufficient brake fluid level warning light
06336 Handbrake ‘on’ warning light
06343 Insufficient engine oil pressure warning light
06344 Insufficient brake fluid level warning light
06345 Fuel reserve warning light
06350 Coolant overheating warning light

Engine cuts out suddenly –
ignition fault
m mLoose or disconnected LT wires
m mWet HT leads or distributor cap (after
traversing water splash)
m mCoil failure (check for spark)
m mOther ignition fault (see Chapter 4)
Engine misfires before cutting out
– fuel fault
m mFuel tank empty
m mFuel pump defective or filter blocked
(check for delivery)
m mFuel tank filler vent blocked (suction will be
evident on releasing cap)
m mCarburettor needle valve sticking
m mCarburettor jets blocked (fuel contami-
nated)
m mOther fuel system fault (see Chapter 3)
Engine cuts out – other causes
m
mSerious overheating
m mMajor mechanical failure (eg camshaft
drive)
Ignition (no-charge) warning light
illuminated
m mSlack or broken drivebelt — retension or
renew (Chapter 9)
Ignition warning light not
illuminated
m mCoolant loss due to internal or external
leakage (see Chapter 2)
m mThermostat defective
m mLow oil level
m mBrakes binding
m mRadiator clogged externally or internally
m mElectric cooling fan not operating correctly
m mEngine waterways clogged
m mIgnition timing incorrect or automatic
advance malfunctioning
m mMixture too weak
Note: Do not add cold water to an overheated
engine or damage may result
Note: Low oil pressure in a high-mileage
engine at tickover is not necessarily a cause
for concern. Sudden pressure loss at speed is
far more significant. In any event check the
gauge or warning light sender before
condemning the engine.
Gauge reads low or warning light
illuminated with engine running
m mOil level low or incorrect grade
m mDefective gauge or sender unit m mWire to sender unit earthed
m mEngine overheating
m mOil filter clogged or bypass valve defective
m mOil pressure relief valve defective
m mOil pick-up strainer clogged
m mOil pump worn or mountings loose
m mWorn main or big-end bearings
Pre-ignition (pinking) on
acceleration
m mIncorrect grade of fuel
m mIgnition timing incorrect
m mDistributor faulty or worn
m mWorn or maladjusted carburettor
m mExcessive carbon build-up in engine
Whistling or wheezing noises
m
mLeaking vacuum hose
m mLeaking carburettor or manifold gasket
m mBlowing head gasket
Tapping or rattling
m
mIncorrect valve clearances (where appli-
cable)
m mWorn valve gear
m mWorn timing chain or belt
m mBroken piston ring (ticking noise)
Knocking or thumping
m
mUnintentional mechanical contact (eg fan
blades)
m mWorn drivebelt
m mPeripheral component fault (generator,
water pump, etc)
m mWorn big-end bearings (regular heavy
knocking, perhaps less under load)
m mWorn main bearings (rumbling and
knocking, perhaps worsening under load)
m mPiston slap (most noticeable when cold)
Engine noises
Low engine oil pressure
Engine overheatsEngine cuts out and will not restart
Fault FindingREF•11
REF
Crank engine and check for spark. Note
use of insulated tool

F
Facia - 12•10, 13•107
Fan -2•3, 13•57, 13•71, 13•84
Fast idle adjustment -3•7, 3•9, 3•10, 3•11,
13•64
Fault finding- REF`•9et seq
Fault finding - braking system -8•9
Fault finding - clutch -5•3
Fault finding - cooling and heating systems
-2•8
Fault finding - driveshafts and hubs -7•6
Fault finding - Econometer -9•12
Fault finding - electrical system -9•14,
REF•9
Fault finding - engine -1•35, 1•36, 2•8,
3•13, 4•9, 13•92, REF•10, REF•11
Fault finding - fuel system -3•9, 3•13,
13•84
Fault finding - ignition system -4•9,
REF•11
Fault finding - Microplex ignition system -
13•92
Fault finding - steering - 10•4
Fault finding - suspension - 11•6
Fault finding - transmission -6•4
Fault finding - turbocharger system - 13•84
Filling - 12•3
Final drive output shafts - 13•94
Fire -0•5
Float adjustment -3•7, 3•8, 3•10, 3•11,
13•64, 13•66
Flywheel -1•19, 1•21, 1•31, 13•46, 13•53
Fog lamps - 13•106
Fuel evaporation control system - 13•78
Fuel filter - 13•67, 13•72, 13•74, 13•79
Fuel gauge fault -9•14
Fuel injection electronic control unit (ECU)
- 13•77
Fuel injection system - 13•68, 13•69
Fuel injection system fault finding - 13•84
Fuel injectors - 13•69, 13•70, 13•71, 13•76,
13•77, 13•81, 13•84
Fuel level transmitter -3•5
Fuel pressure regulator - 13•70
Fuel pump -3•5, 13•61, 13•69, 13•72,
13•76, 13•80, 13•81
Fuel rail - 13•70, 13•81
Fuel system-3•1et seq, 13•60, REF•4
Fuel system fault finding -3•9, 3•13
Fuel tank -3•5, 13•61, 13•72
Fume or gas intoxication -0•5
Fuses -9•5, 13•105
G
Gaiters -7•2, 10•2, 13•98
Gashes in bodywork - 12•2
Gaskets -1•20
Gearbox - SeeTransmission
Gearchange lever -6•2
Gearchange linkage - 13•94, 13•95
Glossary of technical terms- REF•13et seq
Grille - 12•3, 13•113
H
Handbrake -8•8, 8•9, REF•1
Handles - 12•11
HC emissions - REF•4
Headlamp -9•6, 9•7, 13•105, 13•106
Heated tailgate window -9•10
Heater -2•5, 2•6, 13•58, 13•59, 13•108
Heater fault -2•8
Horn -9•6, 13•106
Horn fault -9•14
HT leads - 13•92
Hubs -7•3, 7•4, 11•3
Hydraulic hoses and pipes -8•6
Hydraulic system -8•7
Hydrofluoric acid -0•5
I
Idle speed adjustment -3•7, 13•62, 13•65,
13•68, 13•75, 13•79
Idling fault -1•36, 3•13, 13•84
Ignition coil - 13•86, 13•90, 13•91
Ignition switch -4•8
Ignition system-4•1et seq, 13•85
Ignition system fault finding -4•9, 9•14,
REF•11
Ignition unit - 13•89
Indicators -9•7
Injectors - 13•69, 13•70, 13•71, 13•76,
13•77, 13•81, 13•84
Inlet manifold - 13•70, 13•77, 13•80
Instrument panel -9•8, 13•107
Intercooler - 13•84
Interior lamps -9•5, 9•8
Introduction to the Fiat Uno -0•4
J
Jacking -0•8
Joint mating faces and gaskets - REF•8
Jump starting -0•7
L
Lambda sensor - 13•82
Lamps -9•6, 9•7, 9•8
Leaks -0•9, 1•36, 13•84
LED (light emitter diode) -9•12
Lights fault -9•14
Locknuts,locktabs and washers - REF•8
Locks -9•11, 10•4, 12•4, 12•6, 12•7,
13•109
Loudspeakers -9•11
Lubricants and fluids -0•13
M
Magnetic impulse generator winding -
13•86
Main bearings -1•20, 1•30, 13•52
Maintenance -0•10, 13•18
Manifolds -3•12, 13•70, 13•77, 13•80
Master cylinder -8•5, 13•103, 13•93
Microplex ignition system - 13•86, 13•89Microplex ignition system fault finding -
13•92
Mirrors - 12•11, 13•111, REF•1
Misfire -1•35, 4•9, REF•11
Mixture adjustment -3•7, 13•62, 13•65,
13•68, 13•75, 13•79
MOT test checks- REF•1et seq
Mountings -1•13, 1•27, 13•26, 13•35,
13•49
N
Needle valve - 13•66
Number plate lamp -9•7
O
Oil cooler - 13•36
Oil filter -1•8
Oil level sensor - 13•110, 13•111
Oil pressure fault -1•36, REF•11
Oil pump -1•13, 1•19, 1•22, 1•26, 1•29,
13•24, 13•30, 13•35, 13•46, 13•53
Oil seals -1•20, 13•41, 13•44, 13•45,
13•94, REF•8
Oil,engine -0•6, 0•13, 1•3, 1•4, 1•8
Oil,transmission -0•6, 0•13, 6•1, 13•14,
13•95
Overheating -2•8, 4•9, REF•11
P
Pad wear sensor - 13•110
Pads -8•2, 13•100, 13•101
Parking lamp -9•7
Pedals -5•2, 8•9, 13•92, 13•102
Pinking -1•36, 13•84, REF•11
Pistons -1•12, 1•18, 1•22, 1•26, 1•30,
13•25, 13•26, 13•30, 13•35, 13•47,
13•48, 13•53
Plastic components - 13•111
Points -4•2, 4•3
Poisonous or irritant substances -0•5
Power module - 13•90
Pre-ignition -1•36, 13•84, REF•11
Pressure regulating valve -8•6, 13•102
Pressure sensor - 13•86
R
Radiator -2•3, 12•3, 13•57, 13•113
Radio -9•10, 13•110
Rear lamp cluster -9•7
Regulator (voltage) -9•4
Regulator (window) - 12•7
Relays -9•5, 13•71, 13•105
Repair procedures - REF•8
Respraying - 12•3
Rocker cover - 13•19
Rockers -1•19
Roof rack - 12•11
Routine maintenance -0•10, 13•18
Rust holes in bodywork - 12•2
REF•18Index