Fault finding - fuel system, Fuel system 3•13 – FIAT Uno 45 User Manual

Page 71

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6 On 1116 cc and 1301 cc models, the
exhaust system is of dual downpipe, two
silencer, two section type.
7 The exhaust system is flexibly mounted
(photo).
8 Do not attempt to separate the sections of

the exhaust system, while in position in the
car. Unbolt the pipe from the manifold and,
using a screwdriver, prise off the flexible
suspension rings. Provided the car is then
raised on jacks, ramps or placed over
an inspection pit, the complete exhaust

system can be withdrawn from under the car.
9 If only one section is to be renewed, it is far
easier to separate once the complete system
is out of the car.
10 When refitting, grease the pipe sockets
and fit the clamps loosely until the suspension
rings are connected and the downpipe bolted
up (using a new copper gasket). Check the
attitude of the sections with regard to each
other and the adjacent parts of the
underbody. Fully tighten the clamps and
downpipe flange nuts, remembering to bend
up the lockplate tabs on 1116 cc and 1301 cc
models (photo).
11 On the larger engined models, it may be
necessary to raise the vehicle at the rear and
support it on axle stands so that the rear sus-
pension hangs down and is fully extended.
This will allow sufficient clearance between
the axle and the body for the exhaust system
to be withdrawn.

Fuel system 3•13

3

19.10 Exhaust pipe socket clamp

19.7B Exhaust tailpipe mounting

Fault finding - fuel system

Unsatisfactory engine performance and excessive fuel consumption

are not necessarily the fault of the fuel system or carburettor. In fact they
more commonly occur as a result of ignition and timing faults. Before
acting on the following it is necessary to check the ignition system first.
Even though a fault may lie in the fuel system it will be difficult to trace
unless the ignition is correct. The faults below, therefore, assume that
this has been attended to first (where appropriate).

Smell of petrol when engine is stopped

Leaking fuel lines or unions

Leaking fuel tank

Smell of petrol when engine is idling

Leaking fuel line unions between pump and carburettor

Overflow of fuel from float chamber due to wrong level setting,
ineffective needle valve or punctured float

Excessive fuel consumption for reasons not
covered by leaks or float chamber faults

Worn jets

Over-rich setting

Sticking mechanism

Dirty air cleaner element

Difficult starting when cold

Choke control

Insufficient use of manual choke

Weak mixture

Difficult starting, uneven running, lack of power,
cutting out

One or more jets blocked or restricted

Float chamber fuel level too low or needle valve sticking

Fuel pump not delivering sufficient fuel

Induction leak

Difficult starting when hot

Excessive use of manual choke

Accelerator pedal pumped before starting

Vapour lock (especially in hot weather or at high altitude)

Rich mixture

Engine does not respond properly to throttle

Faulty accelerator pump

Blocked jet(s)

Slack in accelerator cable

Engine idle speed drops when hot

Incorrect air cleaner intake setting

Overheated fuel pump

Engine runs on

Idle speed too high

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