FIAT Uno 45 - Manual (Page 49)

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
Ⅵ Ⅵ Battery discharged
Ⅵ Ⅵ Battery terminals loose or corroded
Ⅵ Ⅵ Battery earth to body defective
Ⅵ Ⅵ Engine/transmission earth strap broken or loose
Ⅵ Ⅵ Disconnected or broken wire in starter circuit
Ⅵ Ⅵ Ignition/starter switch defective
Ⅵ Ⅵ Starter motor or solenoid defective (see Chapter 9)
Ⅵ Ⅵ Major mechanical failure (seizure) or long disuse (piston rings rusted
to bores)
Engine turns and fails to start
Ⅵ Ⅵ Battery discharged
Ⅵ Ⅵ Battery terminals loose or corroded
Ⅵ Ⅵ Battery or engine earth strap loose
Ⅵ Ⅵ Starter motor connections loose
Ⅵ Ⅵ Oil in engine/transmission too thick
Ⅵ Ⅵ Starter motor defective
Ⅵ Ⅵ Vapour lock in fuel line (in hot conditions or at high altitude)
Ⅵ Ⅵ Blocked float chamber needle valve
Ⅵ Ⅵ Fuel pump filter blocked
Ⅵ Ⅵ Choked or blocked carburettor jets
Ⅵ Ⅵ Faulty fuel pump
Ⅵ Ⅵ Fuel tank empty
Ⅵ Ⅵ Other fuel system fault (see Chapter 3)
Ⅵ Ⅵ Shorted or disconnected low tension leads
Ⅵ Ⅵ Dirty, incorrectly set, or pitted contact breaker points
Ⅵ Ⅵ Contact breaker point spring earthed or broken
Ⅵ Ⅵ Faulty condenser
Ⅵ Ⅵ Defective ignition switch
Ⅵ Ⅵ Faulty coil
Ⅵ Ⅵ
Damp or dirty HT leads, distributor cap or plug bodies
Ⅵ Ⅵ Broken, loose or disconnected LT leads
Ⅵ Ⅵ Ignition leads connected wrong way round
Ⅵ Ⅵ Other ignition fault (see Chapter 4)
Ⅵ Ⅵ Valve timing incorrect (after rebuild)
Engine fires but will not run
Ⅵ Ⅵ Insufficient choke (cold engine)
Ⅵ Ⅵ Fuel starvation or tank empty
Ⅵ Ⅵ Ignition fault (see Chapter 4)
Ⅵ Ⅵ Other fuel system fault (see Chapter 3)
Engine stalls and will not restart
Ⅵ Ⅵ Too much choke allowing too rich a mixture to wet plugs
Ⅵ Ⅵ Float damaged or leaking or needle not seating
Ⅵ Ⅵ Float lever incorrectly adjusted
Ⅵ Ⅵ Ignition failure - sudden
Ⅵ Ⅵ Ignition failure - misfiring precedes total stoppage
Ⅵ Ⅵ Ignition failure - in severe rain or after traversing water splash
Ⅵ Ⅵ No petrol in petrol tank
Ⅵ Ⅵ Petrol tank breather choked
Ⅵ Ⅵ Sudden obstruction in carburettor
Ⅵ Ⅵ Water in fuel system
Engine slow to warm up
Ⅵ Ⅵ
Choke linkage maladjusted
Ⅵ Ⅵ Air cleaner temperature control unit defective
Ⅵ Ⅵ Thermostat stuck open (see Chapter 2)
Ⅵ Ⅵ Other fuel system fault (see Chapter 3)
Difficult starting when cold
Ⅵ Ⅵ Insufficient choke
Ⅵ Ⅵ Fouled or incorrectly gapped spark plugs
Ⅵ Ⅵ Damp or dirty HT leads, distributor cap or spark plug bodies
Ⅵ Ⅵ Dirty or maladjusted contact breaker points
Ⅵ Ⅵ Other ignition fault or timing maladjustment (see Chapter 4)
Ⅵ Ⅵ Fuel system or emission control fault (see Chapter 3)
Ⅵ Ⅵ Poor compression (may be due to incorrect valve clearances, burnt
or sticking valves, blown head gasket, worn or damaged pistons,
rings or bores)
Ⅵ Ⅵ Incorrect valve timing (after rebuild)
Difficult starting when hot
Ⅵ Ⅵ Incorrect use of manual choke
Ⅵ Ⅵ Fuel line vapour lock (especially in hot weather or at high altitudes)
Ⅵ Ⅵ Incorrect ignition timing
Ⅵ Ⅵ Other fuel system or emission control fault (see Chapter 3)
Ⅵ Ⅵ Poor compression (see above)
Engine lacks power
Ⅵ Ⅵ Ignition timing incorrect
Ⅵ Ⅵ Contact breaker points incorrectly gapped
Ⅵ Ⅵ Incorrectly set spark plugs
Ⅵ Ⅵ Dirty contact breaker points
Ⅵ Ⅵ Distributor automatic advance and retard mechanisms not
functioning correctly
Ⅵ Ⅵ Other ignition system fault (see Chapter 4)
Ⅵ Ⅵ Air cleaner choked
Ⅵ Ⅵ Carburation too rich or too weak
Ⅵ Ⅵ Fuel filter blocked
Ⅵ Ⅵ Air filter blocked
Ⅵ Ⅵ Faulty fuel pump giving top and fuel starvation
Ⅵ Ⅵ Other fuel system fault (see Chapter 3)
Ⅵ Ⅵ Poor compression
Ⅵ Ⅵ Valve clearances incorrect
Ⅵ Ⅵ Carbon build-up in cylinder head
Ⅵ Ⅵ Sticking or leaking valves
Ⅵ Ⅵ Weak or broken valve springs
Ⅵ Ⅵ Worn valve guides or stems
Ⅵ Ⅵ Worn pistons and piston rings
Ⅵ Ⅵ Burnt out valves
Ⅵ Ⅵ Blown cylinder head gasket (accompanied by increase in noise)
Ⅵ Ⅵ Worn pistons and piston rings
Ⅵ Ⅵ Worn or scored cylinder bore
Ⅵ Ⅵ Brakes binding
Engine misfires throughout speed range
Ⅵ Ⅵ Defective or fouled spark plug
Ⅵ Ⅵ Loose, cracked or defective HT lead
Ⅵ Ⅵ Maladjusted, sticking or burnt valves
Ⅵ Ⅵ Ignition timing incorrect
Ⅵ Ⅵ Blown head gasket
Ⅵ Ⅵ Fuel contaminated
Ⅵ Ⅵ Other ignition fault (see Chapter 4)
Ⅵ Ⅵ Other fuel system fault (see Chapter 3)
Poor engine braking
Ⅵ Ⅵ High idle speed
Ⅵ Ⅵ Other fuel system fault (see Chapter 3)
Ⅵ Ⅵ Low compression