Motor FIAT PUNTO 1998 176 / 1.G User Guide

2D*10 Engine removal and overhaul procedures
05 Remove the brush holder assembly from the automatic transmission as described in Chapter 7B, Section 4. The brushes bear on the slip rings at the rear of the electro-magnetic clutch housing and they may be damaged when the transmission is removed. 86 Unscrew and remove the transmission-to-engine bolts then carefully draw the transmission away from the engine, resting It securely on wooden blocks. Collect the locating dowels If they are loose enough to be extracted, 87 If the oil pump driveshaft remains engaged with the crankshaft, remove it and reert Into the transmission to protect It from damage.
Connection 86 If the engine and transmission have not been separated, go to paragraph 104. Manual transmission models 89 Smear a little high-melting-point grease
on
the splines of the transmission input shaft. Do not use an excessive amount as there Is the risk of contaminating the clutch friction plate. 90 Carefully offer up the transmission to the engine cylinder block, guiding the input shaft through the clutch friction plate. 91 Refit the transmission-to-engine bolts and
the
single nut. hand^jghtenlng 1hem to secure the transmission in position. Note: Do not hghten them to force the engine and transmission together. Ensure that the beilhousing and cylinder block mating faces will butt together evenly without obstruction, before finally tightening the bolts and nut securely. Automatic transmission models 92 Check that the oil pump driveshaft is correctly engaged with the oil pump in the transmission. 93 Carefully offer up the transmission to Ihe rear of the engine and insert the oil pump driveshaft In the centre of the electro-magnetic clutch housing. Locate the transmission on the locating dowels then Insert the bolts and tighten them securely. 94 Refit the brush holder assembly to the automatic transmission with reference to Chapter 7B, Section 4. Petrol engines 96 Refit the transmission lower cover and tighten the bolts. 96 Locate the support bracket on the lower cover, then insert the bolts hand-tight. Also Insert the bolts securing the bracket lo the rear of Ihe cylinder block. With all the bolts Inserted, tighten them securely. 97 Refit the earth leads and tighten the bolts. Diesel engines 98 Refit the rpm sensor and tighten the bolts. 99 Insert the Intermediate shaft through the bracket then locate the dust boot on it and insert the Inner end in the transmission.
100 Refit and tighten the bolts securing the Intermediate shaft to the bracket on the rear of the cylinder block. 101 Refit the transmission lower cover and tighten the bolts. Ail models 102 Refit the starter motor (see Chapter 5A). 103 Refit the wiring harness to the components on the engine/transmission assembly making sure it is routed correctly.
Refitting 104 Locate the engine/transmission assembly beneath the engine compartment and attach the hoist to the lifting eyes. 105 Carefully lift the assembly up into the engine compartment taking care not to damage the surrounding components. 106 Reconnect the left-hand engine/trans-mission mounting to the body and tighten the bolts. 107 Reconnect Ihe right-hand engine mounting to the body and tighten the bolts. 108 Working beneath the vehicle, refit the rear engine mounting and tighten the bolts. 109 Disconnect the hoist from the engine and transmission lifting eyes and remove the hoist from under the vehicle. 110 The remainder of the refitting procedure is the direct reverse of the removal procedure, noting the following points:
a) Ensure that alf sections of the wiring harness follow their original routing; use new cable-ties to secure the harness In position, keeping it away from sources
of
heat and abrasion. b) On vehicles with manual transmission check and if necessary adjust the gearchenge cable and rod with reference to Chapter 7A. c) On vehicles with automatic transmission use new ro//p/ns fo secure the driveshafts to the transmission output stubs. Also check and if necessary adjust the kickdown end selector cables with reference to Chapter 78. d) Ensure that afi hoses are correctly routed and are secured with the correct hose clips, where applicable. If the hose clips cannot be used again; proprietary worm drive clips should be fitted
In
their place. e) Refill the cooling system as described in Chapter 1A or 18. f) Refill the engine with appropriate grades and quantities of oil (Chapter
1A
or 1B). g) Refit and adjust the auxiliary drivebelt(s) wfth reference fo Chapter 1A or 1B. h) Check and If necessary adjust the accelerator cable with reference to Chapter
AA,
48 or
AC.
i) When the engine is started for the first time, check for
air,
coolant, lubricant and fuel leaks from manifolds, hoses etc. If
the
engine has been overhauled, read
the
notes In Section 13 before attempting to starlit.
5 Engine overhaul • dismantling sequence
1 It is much easier to dismantle and work on the engine if it is mounted on a portable engine stand. These stands can often be hired from a tool hire shop. Before the engine is mounted on a stand, the flywheel should be removed, so that the stand bolts can be tightened Into the end of the cylinder block/crankcase. 2 If a stand Is not available, it Is possible to dismantle the engine with it blocked up on a sturdy workbench, or on the floor, Be very careful not to tip or drop the engine when working without a stand. 3 If you intend to obtain a reconditioned engine, all anclllarles must be removed first, to be transferred to the replacement engine (just as they will If you are doing a complete engine overhaul yourself). These components Include the following:
Petroi engines a) Power steering pump if removed with the engine (Chapter
10).
b) Alternator fmcluding mounting brackets) and starter motor (Chapter
SA).
c) The Ignition system and HT components including ail sensors, HT leads and
spark
plugs (Chapters 1A and
SB).
d) The fuel injection system components (Chapters A A and
AB).
e) All electrical switches, actuators and sensors, and the engine wiring harness (Chapters 4A, AB, SB). f) Inlet and exhaust manifolds (Chapters 4A, AB end
AD).
g) Engine oil dipstick and tube. h) Engine mountings (Chapter
2A).
i) Flywheef/driveptate (Chapter
2A).
j) Clutch components (Chapter
6)
- manual transmission. k) Electro-magnetic clutch components (Chapter 7B) - automatic transmission. I) Cooling system components (Chapter
3).

Diesei engines a) Power steering pump //removed with the engine (Chapter
10).
b) Alternator (Including mounting brackets) and starter motor (Chapter 5A). c) The glow plugfpre-heatlng system components (Chapter
SC).
d) Ait fuel system components, including the fuel injection pump, all sensors and actuators (Chapter
AC).
e) The vacuum pump. f) Ail electrical switches, actuators and sensors, and the engine wiring harness (Chapter 4C and 5C). g) Inlet and exhaust manifolds and, where applicable, the turbocharger (Chapter
AC
and 4D). h) The engine oil level dipstick and its tube. i) Engine mountings (Chapter
2C).

2D*10 Engine removal and overhaul procedures
12.18 Angle-tightening the main bearing cap bolts (petrol engine)
12.Ida Application area for silicone Instant gasket on crankshaft rear oil seal housing (petrol engine) 12.19b Refitting the crankshaft rear oil seal housing (petrol engine)
19 Fit a new oil seal to the crankshaft rear oil seal housing. Apply grease to the seal lips. On 1108 cc petrol engines a conventional gasket Is not used at the oil seal retainer joint face, but a 3 mm diameter bead of RTV (Instant) silicone gasket must be applied as shown -allow at least one hour 1or the gasket to cure before oil contacts it. On all other engines a gasket Is fitted Securely tighten the housing bolts (see Illustrations). 20 Check that Ihe crankshaft rotates freely by turning It by hand. If resistance Is fell, re-check the running clearances, as described above. 21 Carry out a check of the crankshaft endfloat as described at the beginning of Section 8. If the thrust surfaces of the crankshaft have been checked and new thrust washers hove been fitted, then the endfioat should be within specification.
22 Refit the pistons and connecting rods as described in Section 7. 23 Refit the flywheeVdriveplate, and-vibration plate (16-valvo engines), oil pump and pick-up tube, and sump with reference to the relevant Sections of Parts A, B or C of this Chapter.
13 Engine -initial start-up after overhaul and reassembly
1 With the engine refitted In the vehicle, double-check the engine oil and coolant levels. Make a final check that everything has been reconnected, and that there are no tools or rags left In the engine compartment.
Petrol engine models 2 Remove the spark plugs, then disable the
ignition system by disconnecting the LT wiring plug to the ignition colls. 3 Turn the engine on the starter until Ihe oi pressure warning light goes out. Refit ihe spark plugs, and reconnect the LT wiring.
Diesel engine models 4 Disconnect tho wiring from the stop solenoid on the Injection pump, then turn the engine on the starter motor until the oil pressure warning light goes out. Reconnect ihe wire to the stop solenoid. 6 Fully depress the accelerator pedal, turn tho ignition key to its first position and wait tor HHJ preheating warning light to go out.
All models 6 Start the engine, noting that this may take i little longer than usual, due to the fuel system components having been disturbed.
12.19c On diesel engines use a screwdriver to prise out the rear oil seal 12.19d Locate the new oil soalln the housing (diosel engine)... 12.19e ... and use a block of wood to drive it in
12.19f On Diesel engines fit the gasket to the cylinder block ... 12.19g ... then locate the rear oli seal housing... 12.19h ... and Insert the bolts

3*2 Cooling, heating and ventilation systems
Testing 7 A rough test of the thermostat may be made by suspending it with a piece of siring in a container full of water. Heat tho water to bring it to the boii and observe the movement of the vaive shaft through the inlet port (see illustrations). 6 The thermostat valve must be fully open, by the time the water boils. If not, renew the complete IhermOstat/housIng assembly. 9 If a thermometer is available, the precise opening temperature of the thermostat may be determined; compare with the figures given in the Specifications. The opening temperature Is also marked on the thermostat housing. 10 Note that a thermostat which falls to close completely as ihe water cools must also be renewed.
Refitting 11 Ensure that the cylinder head and thermostat housing mating surfaces are
completely clean and free from ail traces of Ihe old gasket material. 12 Lay a new gasket In position on the cylinder head, then fit the thermostat housing and Insert retaining bolts, tightening them securely.
Caution: Do not over-tlghten tho retaining bolts, as tho alloy casting could easily be damaged 13 Where applicable, transfer the cooling fan switch and coolant temperature sensor to the new housing. 14 Refit the coolant hose(s) to the ports on the thermostat housing and lighten the clips securely. 15 Where applicable, refit the harness/hose support bracket to the thermostat housing and tighten the bolts securely. Also refit the air cleaner and Inlet ducts as described in Chapter 4B 15 Refill the cooling system as described in Chapter 1A or 1B.
5 Electric cooling fan(s) -testing, removal and refitting ^
Testing 1 Detailed fault diagnosis should be camw out by a Rat dealer using dedicated tesl equipment, but basic diagnosis can be car&c out as follows. 2 If the fan does not appear to work, run if* engine until normal operating temperature s reached, Ihen allow It to idle. The fan shouldcti In within a few minutes (before lite temperalure gauge needle enters the red section), il nol. switch off the engine and disconnect tfie cooling fan motor wiring connector. 3 The motor can be tested by disconnecting it from the wiring loom, and connecting a 12? volt supply directly to It. The motor should operate - if not. the motor, or the motor wiring. Is faulty.
frotf heater from cylinder head mdotor
4.7b Thermostat operation in the fully closed position (diesel engine)
from neoier Irom cylinder head radiator
4.7c Thermostat operation in the fully open position (diesel engine)

3*2 Cooling, heating and ventilation systems
4 If the motor operates when tested as described, (he fault must lie In the engine wring harness or the temperature sensor. The temperature sensor/switch can be tested as described in Section 6. Any further fault Diagnosis should be referred to a suitably-equipped Fiat dealer - do not attempt to test
Ihe
electronic control unit.
Removal 5 Disconnect the battery negative terminal (refer to D/scon oecf/ng the battery in the Reference Section of this manual). 6 On diesel engine models, unbolt the relay bracket from the side of the battery tray to improve access. On 1242 cc {16-valve) petrol engine models, remove the air cleaner and
inset
ducts as described in Chapter 4B. 1 Disconnect the motor wiring connectorfs). 8 Unbolt the shroud from the rear of the ratiator. then lift out the cooling fan assembly. Refitting 9 Refitting is a reversal of removal
6 Cooling fan switch -testing, removal and refitting ^
Testing 1 The switch is threaded into the lower left
nand
comer of the radiator. 2 The switch can be tested by removing it,
and
checking that the switching action occurs
at
the correct temperature {heat the sensor in a container of water, and monitor the temperature with a thermometer). 3 There should be no continuity between the switch terminals, until Ihe specified cooling fan cut-In temperature Is reached, when continuity (and zero resistance) should exist between the terminals.
Removal 4 Disconnect the battery negative terminal refer to Disconnecting the battery in the Reference Section of this manual). 5 Allow the engine to cool completely, then drain the cooling system as described in Chapter 1Aor 1B. 6 Disconnect the wiring plug from the sensor.
bolts...
7 Carefully unscrew the sensor and. whore applicable, recover the sealing ring. Refitting 8 If the sensor was originally fitted using sealing compound, clean the sensor threads thoroughly, and coat them with fresh sealing compound. 9 If the sensor was originally fitted using a sealing ring, use a new sealing ring on refitting. 10 Refitting is a reversal of removal, but refill the cooling system as described in Chapter 1A or 18. 11 On completion, start the engine and run it until it reaches normal operating temperature. Continue to run the engine until the cooling fan cuts in and out correctly.
7 Coolant pump • & removal, inspection 5 and refitting
Removal
Petrol engine models 1 Disconnect the battery negative terminal (refer to Disconnecting the battery in the Reference Section of this manual). 2 Drain the cooling system and remove the auxiliary drivebett(s) as described In Chapter 1 A. 3 Remove the timing belt as described In Chapter 2A or 28. 4 Unscrew the securing bolts/nuts, and withdraw the coolant pump (see illustrations).
7.9b ... and lift off the pulley (diesel engine)
(petrol engine) If the pump Is stuck, tap it gently using a soft-faced mallet - do not lever between the pump and cylinder block mating faces.
Diesel engine models 5 Disconnect the battery negative terminal (refer to D/s connecting the battery in the Reference Section of this manual). 6 Drain the cooling system as described in Chapter 1B. 7 Remove the auxiliary drivebelt(s) as descnbed In Chapter 1B. 6 On models fitted with power steenng, refer to Chapter 10 and remove the power steering pump from its mountings; this can be achieved without disconnecting the power steering fluid hoses from the pump. Tie the pump away from the work area, taking care to avoid kinking the fluid hoses. 9 Unscrew the securing bolts, and remove the coolant pump pulley. It will be necessary to counterhold the pulley In order to unscrew the bolts, and this is most easily achieved by wrapping an old drivebelt tightly around the pulley to act in a similar manner to a strap 3 wrench. Alternatively, a stout screwdriver can be braced between two of the pulley bolts while the third is slackened (see illustrations). 10 Disconnect ihe bypass hoses from the coolant pump outlet stubs. 11 Unscrew the securing bolts, and withdraw the coolant pump assembly. Note that the pump must be detached from the transfer pipe than runs behind the cylinder block to the thermostat housing (see illustration). The pipe is a push fit in the port on the rear of the coolant pump
7.11 Removing the coolant pump assembly (diesel engine)

3*2 Cooling, heating and ventilation systems
12 If tho pump is stuck, tap It gently using a soft-faced mallet • do not lever between the pump and cylinder block mating faces.
Inspection 13 Check the pump body and impeller for signs of excessive corrosion. Turn the impeller, and check for stiffness due to corrosion, or roughness due to excessive end play. 14 Check the clearance between the pump Impeller and the casing using a feeler blade (see Illustration). If the clearance is different to that given In the Specifications, the pump must be renewed. No spare components are available; the pump can only be renewed as a complete assembly. 15 On diesel engine models, remove the O-rlng at the end ol the transfer pipe, which runs behind Ihe cylinder block and fits Into the rear of the coolant pump. A new O-rlng should be fitted as a matter of course.
Refitting
Petrol engine models 16 Commence refitting by thoroughly cleaning all traces of sealant from the mating faces of the pump and cylinder block/pump housing. 17 Apply a continuous bead of sealant {liquid gasket) to the cylinder block mating face of the pump, taking care not to apply excessive sealant, which may enter the pump itself (see Illustration). 18 Place the pump In position In Its housing, then refit and lighten the bolts/nuts to the specified torque. 19 Refit the liming belt as described In Chapter 2A or 28. 20 Refit the auxiliary drivebeltfs) and refill the cooling system as described in Chapter
t
A. 21 Reconnect Ihe battery negative terminal. Diesel engine models 22 Commence refitting by thoroughly cleaning all traces of old gasket from the mating faces of the pump housing and cylinder block. 23 Place a new gasket in position on (he cylinder block, locate the pump in position, then refit and tighten the bolts (see
7.17 On petrol engine models, apply a continuous bead of sealant (liquid gasket) to the pump mating face
pump Impeller and the casing using a feeler blode (diesel engine) illustration). Ensure that the end of the coolant transfer pipe seats firmly In tho port at the rear of the coolant pump, without displacing the O-ring seal. 24 Refit Ihe pump pulley, then refit the securing bolts and tighten to the specified torque. Counterhofd the pulley using the same method employed during removal. 25 Where applicable, refit the power steering pump with reference to Chapter 10. 26 Refit and tension the auxiliary drivebelt(s) as described in Chapter 18. 27 Refill (he cooling system as desenbed in Chapter 1B. 28 Reconnect the battery negative terminal.
8 Heater/ventilation components - § removal and refitting
Complete heater assembly

A


Warning: On mode's fitted with air conditioning, do not attempt to remove the cooling unit, which Is located between the heater blower motor casing and the main heater assembly. Romovat of the cooling unit entails disconnection of refrigerant lines - refer to Section 10 for precautions to be observed.
rfJS
tf In any doubt as to the procedure fo follow on models with air conditioning, consult a Fiat dealer for advice. Note: This is an involved procedure, and It (s recommended fhat the following Section fs read thoroughly before commencing work. Plenty of time should be allowed to compter the operation. During dismantling, make notes on the routing of all wiring and cables, and the locations of all fixings, to aid reassembly. Removal 1 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual), 2 Set the heater control to HOT. then drain the cooling system as described In Chapter 1A or 18. 3 Working in the engine bay, slacken the clips and dotach the healer unit coolant hoses from the ports at the bulkhead (see illustration) Recover the rubber grommets. 4 Refer to Chapter 11 and remove the entire facia assembly from the vehicle bulkhead. Rest the assembly on the front seats. 5 At this stage, access to the air l nlet/dlstrl but Ion/blending control cables is possible. These can be easily disconnected from their respective control levers and renewed If required. 6 Working from the engine bay. remove the protective plastic caps to expose the heater assembty mounting studs and remove the nuts 7 Label the electrical connections to 1hi» heater assembly, to aid correct refitting later and then unplug them at the connectors 8 Slacken and remove the nuts and lift the healer assembly off its mounting studs. Refitting 9 To refit the assembly, reverse the steps described for removal, bearing in mind the following points: a) Make sure that all wiring and cables are muted as noted during dismantling. b) Make sure that dl air ducts are securely reconnected. c) Refit the facia components with reference to Chapter 11. dl On completion, refill the cooling system as described In Chapter 1A or 18.
8.3 Slacken the clips (arrowed) and detach the heater unit coolant hoses from the ports at the bulkhead

3*2 Cooling, heating and ventilation systems
Heater matrix Removal 10 Remove the complete heater assembly as described previously in this Section. 11 Slacken and remove the securing screws, then withdraw the heater matrix from the tester assembly casing. Refitting 12 Refitting is a reversal of removal; refit Ihe neater assembly as described previously in
this
Section.
Heater blower motor
Removal 13 Disconnect the battery negative terminal {refer to Disconnecting the battery in the Reference Section of this manual). 14 Unplug the wiring from the blower motor
al the
connector. 15 Working in the passenger front footwell, under the glovebox. remove the securing grows and lower the blower motor and rotor assembly from Its casing (see illustration). Refitting
16 Refitting is a reversal of removal.
Heater blower motor resistor
Removal 17 The resistor is located at the bottom of the heater casing, behind the blower motor. 18 Disconnect the battery negative terminal (refer to O/sconnecf/ng the battery in the Reference Section of this manual). 19 For improved access, remove the blower motor as described in the previous sub-Section. 20 Disconnect the wiring plug from the resistor. 21 Working under the glovebox. remove the two securing screws, and withdraw the resistor from the blower unit case (see lustrations).
8.15 Removo the securing screws and lower the blower motor and rotor assembly from its casing Refitting 22 Refining Is a reversal of removal.
Heater control panel
Removal 23 Pull the ventilation fan speed control knob from the panel. 24 Unscrew and remove the three screws securing the panel cover. Two screws are under the lower edge of the panel, whilst Ihe remaining screw is located in the ventilation fan speed control knob recess. Remove the panel. 25 Unscrew and remove the four screws securing the control panel to the facia. The screws are located in each comer of the panel. 26 Remove the facia as described in Chap-ter 11. 27 Make a careful note of the cable and electrical connections. Unscrew the cable clamps and unclip the inner cables from the controls. Unplug the ventilation fan speed control. 28 Unclip and remove the control panel from the heater distributor box assembly. Refitting 29 Refitting is a reversal of removal.
9 Air conditioning system -general Information and precautions
General information An air conditioning system is available on certain models. It enables the temperature of Incoming air to be lowered, and also dehumidifies the air, which allows rapid demisting and increased comfort. The cooling side of the system works In the same way as a domestic refrigerator. Refrigerant gas is drawn into a belt-driven compressor where the increase In pressure causes the refrigerant gas to turn to liquid. It then passes through a condenser mounted on the front of the radiator, where it is cooled. Tho liquid then passes through an expansion vaive to an evaporator, where it changes from liquid under high pressure to gas under low pressure. This change is accompanied by a drop in temperature, which cools the evaporator and hence the air passing over it. The refrigerant returns to the compressor, and the cycle begins again. The air bfown through the evaporator passes to the air distribution unit where it is mixed, if required, with hot air blown through the heater matrix to achieve the desired temperature in the passenger compartment. The heating side of ihe system works in the same way as on models without air conditioning (see Section 8). The system Is electronically-controlled. Any problems with the system should be referred to a Fiat dealer.
Precautions With an air conditioning system. It is necessary to observe special precautions whenever dealing with any part of the system, or its associated components. If for any reason the system must be disconnected, it Is
8.21a Remove the two securing screws (arrowed)... ,21b ... and withdraw the resistor from the blower unit case

4A«1
Chapter 4 Part A:
Fuel system - single-point petrol injection models
Contents
Accelerator cable • removal, refitting and adjustment 4 Air cleaner and inlet system - removal and refitting 2 Air cleaner filter element renewal See Chapter 1A Engine management system components - removal 8nd refitting .. 5 fuel filter renewal See Chapter 1A Fuel injection system - depressurlsatlon 8 Fuel injection system • testing and adjusting 10
Degrees of difficulty
Fuel pump/fuel gauge sender unit - removal and refitting 8 Fuel tank - removal and refitting 7 General information and precautions 1 Idle speed and mixture adjustment See Chapter 1A Inlet air temperature regulator • removal and refitting 3 Inlet manifold - removal and refitting 9 Unleaded petrol - general Information and usage 11
Easy, suitable for Fairty easy, suitable Fairly difficult, Jx suitable for competent ^ OY mechanic ^
DifficUt, suitable tor % Very difficult, ^ novice with Me for begrmer with &
Fairly difficult, Jx suitable for competent ^ OY mechanic ^ experienced DIY > * suitable for expert D(Y JS or professional ^ experience some experience &
Fairly difficult, Jx suitable for competent ^ OY mechanic ^ mechanic > * suitable for expert D(Y JS or professional ^
Specifications
System type Weber-Marelll integrated single-point fuel injection/ignition system
Fuel system data Fuel pump type Electric, Immersed in fuel tank Fuel pump delivery rate 110 litres/hour minimum Regulated fuel pressure 1.0 ± 0.2 bar Crankshaft TDC sensor resistance at 20°C €50 to 720 ohms Injector duration (at idle)
1
£ ms
Recommended fuel Minimum octane rating 95 RON unleaded
Torque wrench settings Nm ibfft Coolant temperature sensor 3 2 Fuel filter collar nut S 4 Fuel tank 28 21 Idle control stepper motor 4 3 Inlet manifold 27 20 Inlet union to filter 31 23 Outlet union to filter 15 11 Throttle body to manifold 7 5 Throttle potentiometer 3 2

4A*2 Fuel system - single-point petrol Injection models
1 General information and precautions
General information The iAW Weber-Marelli single point Injection (SPI) system is a self-contained engine management system, which controls both the fuel Injection and Ignition (see Illustration), This Chapter deals with the fuel Injection system components only - refer to Chapter 5B for details ol the ignition system components. The fuel Injection system comprises a fuel tank, an electric fuel pump, a fuel filter, fuel supply and return lines, a throttle body with an integral electronic fuel Injector, and an Electronic Control Unit (ECU) together with its associated sensors, actuators and wiring. The fuel pump delivers a constant supply of fuel through a cartridge fitter to the throttle body, and the fuel pressure regulator (integral with the throttle body) maintains a constant fuel pressure at the fuel injector and returns excess fuel to the tank via the return line. This
constant flow system also helps to reduce fuel temperature and prevents vaporisation. Tne fuel injeclor Is opened and closed by an Electronic Control Unit (ECU), which calculates the injection timing and duration according to engine speed, throttle position and rate of opening, Inlet air temperature, coolant temperature and exhaust gas oxygen content information, received from sensors mounted on the engine. inlet air is drawn Into the engine through the air cleaner, which contains a renewable paper filter element. The inlet air temperature is regulated by a vacuum operated valve mounted in the air ducting, which blends air at ambient temperature with hot air, drawn from over the exhaust manifold. Idle speed is controlled by a stepper motor located on the side of the throttle body. Cold starling enrichment is controlled by the ECU using the coolant temperature and inlet air temperature parameters to increase the injector opening duration. The exhaust gas oxygen content is constantly monitored by the ECU via the Lambda (oxygen) sensor, which is mounted in
me exhaust downpipe. The ECU then uses this Information to modify the Injection timing and duration to maintain the optimum air/fuel ratio. An exhaust catalyst Is fitted to all SPI models. The ECU also controls the operation of the activated charcoal filter evaporative loss system • refer to Chapter 4D for further details. It should be noted that fault diagnosis of the I IAW Weber-Marelli system is only possible with dedicated electronic test equipment. Problems with the system should therefore be I referred to a Flat dealer for assessment. Once i the fault has been Identified, the I removal/refitting procedures detailed in the following Sections can then be followed.
Precautions |

A


Warning: Many procedures in thH Chapter require the removal ot fuel lines and connections, which may result in fuel spillage. Before carrying | out any operation on Me fuel system, refer to the precautions given In Safety flrstt at the beginning ot this manual, and follow them Implicitly. Petrol Is a highly dangerous and volatile liquid, and the precautions
1.1 IAW Weber-Marelli single point Injection (SPI) system 1 Fuel
tank
2 Fuel pump 3 Fuel filter 4 Anii'reflux valve 5 Fuel pressure regulator 6 Injector
7 Air cleaner 8 Fuel vapour
trap
9 Idle stepper motor
10
Absolute pressure sensor J11njection/ignition ECU 12 Tnrottle position sensor
13 Engine coolant temperature sensor 14 Intake air temperature sensor 15 Inject'onfignitron dual
relay
16 Ignition coils 17 Rpm and TDC sensor
18 Spark plugs 79 Diagnostic socket 20 EVAP solenoid 21 Lambda/oxygen sensor 22 Rev counter 23 IAW failure warning light

4A*2 Fuel system - single-point petrol Injection models
2.4a Disconnect the large breather hose... ziecessary when handling it cannot be mrstressed. Note that residual pressure
wttf
remain in the tuei lines long after the wh/cte was last used, When disconnecting any fuel line, first depressurise the fuel
system
(see Section 8).
2 Air cleaner and intet system • removal and refitting
1
Accelerator cable -removal, refitting and adjustment l
Removal 1 Remove the air cleaner element as described in Chapter 1A. 2 Disconnect the outer section from the hot
air
tube and the inlet air duct and remove it
from
the engine compartment. 3II necessary remove the inlet air duct. 4 Disconnect Ihe large and small breather
roses
from the inner section of the air cleaner, tftsn unscrew the retaining nuts and lift the section from the throttle body (see lustrations).
5
Recover the sealing ring. Check the ring for condition and renew it if necessary.
6
Wipe clean the inner surfaces of both the merand outer sections of the air cleaner. Refitting 7 Refitting Is a reversal ol removal but renew
tie
element
H
necessary.
3 Inlet air temperature regulator -removal and refitting
Removal t
The
thermostatically-controlled cold air flap cpener is located in the air cleaner outer ttsrig section. To check the unit, disconnect
ire air
inlet duct with the engine cold and use imrrorto check that the flap Is positioned to aJmit only hot air from the shroud on the utaust manifold. Next, warm up the engine
and
check that the flap moves to admit only sett air from the inlet duct. If the unit is faulty fl must be renewed.
2
Remove the air cleaner element as •senbod in Chapter
1
A.
kickdown cable adjustment as described in Chapter 7B before adjusting the accelerator cable • in its rest position the accelerator pedal should have approximately 8.0 mm free travel.
5 Engine management system components -removal and refitting I
2.4b ... and the small breather hose ...
3 Unscrew the retaining screw and remove the regulator from the air cleaner outer section.
Refitting 4 Refitting is a reversal of removal.
Removal 1 Remove the air cleaner and air inlet ducting as desenbed in Section 2. 2 To release the cable from the throttle body, unscrew the outer cable locknuts, then disengage the inner cable from the throttle cam, and release the outer cable from its mounting bracket. 3 Working under the instrument panel inside the vehicle, unhook the cable from the fork at the top of the pedal arm. 4 Release the bulkhead grommet and withdraw the accelerator cable from Inside the engine compartment.
Refitting and adjustment 5 Refitting is a reverse of the removal process, but adjust the cable (by means of the outer cable locknuts) so that there is only a very small amount of free play present at the throttle body end of the inner cable. Have an assistant depress the accelerator pedal, and check that the throttle cam opens fully and returns to the at-rest position, then secureJy tighten the cable locknuts. On Selecta models, check the
Note: Refer to the warning given in Section 1 before proceeding. Throttle body assembly
Removal 1 Remove the air cleaner and air duct as desenbed in Section 2. 2 Disconnect the wiring connectors from the throttle potentiometer, idle control stepper motor, inlet air temperature sensor and the injector wiring loom connector situated on the front of the throttle body. 3 Depressurise the fuel system with reference to Section 8, then release the retaining clips and disconnect the fuel feed and return hoses from the throttle body assembly, if the original Fiat retaining clips are still fitted, cut the clips and discard them; replace them with standard luel hose clips on refitting. 4 Slacken the accelerator cable locknuts, then disengage the inner cable from the throttle cam and froe tho outer cable from its retaining bracket. Position the cable clear of the throttle body. 5 Disconnect the EVAP purge valve hose, and the MAP sensor hose from the rear of the throttle body. 6 Slacken and remove the four bolts securing the throttle body assembly to tho Inlet manifold, then remove the assembly along with its insulating spacer. Refitting 7 Refitting is a reversal of the removal pro-cedure, bearing in mind the following points: a) Examine the insulating spacer for signs of damage, and renew //necessary, b) Ensure that the throttle body, inlet manifold and insulating spacer ma ting surfaces are clean and dry, then fit the throttle body and spacer, and securely tighten the retaining bolts.
2.4c ... then remove the retaining nuts. 2.4d ... and remove the air cleaner inner section

4A*2 Fuel system - single-point petrol Injection models
motor c) Ensure that all hoses are correctly reconnected and, where necessary, that their retaining clips are securely tightened. d) Adjust the accelerator cable as described In Section 4.
Fuel injector Note: If a faulty Injector Is suspected, before condemning the Injector, it is worth vying the effect of one of the proprietary Injector cleaning treatments. Removal 8 Remove the air cleaner and air duct as described In Section 2. 9 Disconnect the wiring then unscrew the mounting screws and remove Ihe Injector from the throttle body. Refitting 10 Refitting is a reversal of removal.
Fuel pressure regulator
Removal 11 Remove Ihe air cleaner and air duel as described In Section 2. 12 Using a marker pen. make alignment marks between the regulator cover end the throttle body, then undo the four retaining
screws. As the screws are loosened, place a rag over the cover to catch any fuel spray which may be released. 13 Lift off the cover, then remove the spring and withdraw the diaphragm, noting Its correct fitted orientation. Remove all traces of dirt, and examine the diaphragm for signs of splitting. If damage Is found, it will be necessary to renew the complete upper throttle body assembly. Refitting 14 Refitting is a reversal of removal ensuring that the diaphragm and cover are fitted the correct way round, and that the retaining screws are securely tightened,
Idle control stepper motor
Removal 15 Disconnect the battery negative terminal (refer to Disconnecting the battery In the Reference Section of this manual), then remove the air cleaner and air duct as described in Section 2. 16 Using a crosshead screwdriver, unscrew the mounting screws and remove the stepper motor from the throttle body. Recover the gaskei (see illustration). 17 Clean the unit and check for damage and wear. Refitting 18 When refitting the unit use a new gasket and make sure that the plunger is inserted correctly using the following procedure. Insert the unit and refit the mounting screws loosely. Reconnect the wiring then switch on the ignition several times so that the unit centralises itself. Finally fully tighten the mounting screws to the specified torque. Note: The mounting screws are covered with a locking agent and must be renewed every time they are removed 19 Leave the battery negative terminal disconnected for about 20 minutes - the injection/ignition ECU will position the Idle control stepper motor correctly the first time the engine is started. Reconnect the battery negative terminal.
Throttle potentiometer
Removal 20 Remove the air cleaner and air duct as described in Section 2. 21 Disconnect the wiring from the throttle potentiometer. 22 Using an Allen key unscrew the mounting screws then withdraw the unit from the throttle body (see Illustration). Note: The mounting screws ere covered with a locking agent and must be renewed every time they are removed. Refitting 23 When refitting the unit make sure that the pin Is correctly engaged, and tighten the mounting screws to the specified torque. 24 If a Rat test Instrument is available, the
operation of the throttle potentiometer can be checked at this stage. Before connecting the wiring first turn Ihe ignition key to position MAR and wait a few seconds, then return the key to the STOP position, Reconnect the wiring and connect the test instrument. Turn the Ignition key to the MAR position and cancel the error that will appear. The throttle position Indicated should be between 0° and 4°. If greater than this, check thai the accelerator cable is correctly adjusted however If the correct reading cannot be obtained renew the unit.
Inlet air temperature sensor
Removal 25 Remove the throtlle body assembly as described earlier In this Section. 28 Extract the plastic pins and remove the press-fit cover from the top of the throttle body. 27 Invert the cover then unscrew the mounting screws and remove the Inlet air temperature sensor from the cover. Refitting 28 Refining Is a reversal of removal.
Manifold absolute pressure (MAP) sensor
Removal 29 The manifold absolute pressure sensor is located on the left-hand side of the bulkhead. 30 Unscrew the mounting screws and remove the sensor from the bulkhead, Disconnect the wiring and vacuum pipe. Refitting 31 Refitting is a reversal of removal, but check the condition of the vacuum pipe and renew it if necessary.
Coolant temperature sensor
Removal 32 The coolant temperature sensor Is located on the left-hand side of the inlet manifold. Drain the cooling system as described In Chapter 1A before removing it. 33 Disconnect the wiring. 34 Unscrew the sensor and remove It from the Inlet manifold. If using a socket take care not to damage Ihe wiring connector on the sensor. Refitting 35 Refitting Is a reversal of removal bui tighten Ihe sensor to the specified torque. Do not exceed the specified torque otherwise the unit may be damaged.
Crankshaft TDC sensor
Removal 36 The crankshaft TDC sensor Is located on the front side of the crankshaft pulley. Firmly apply the handbrake, then jack up the front of the car Bnd support It securely on axle stands (see Jacking end vehicle support). Remove 5.22 Throttle potentiometer mounting screws