Fiat 1996 Brava Service Manual page 289

Engine Bravo- Brava @ii
6
v
Fuel system ■■_ '_ 98 range
10.
ANTI-EVAPORATION SYSTEM COMPONENTS
Multi-purpose valve
This valve is used to carry out various functions, namely:
- to prevent the flow of liquid fuel if the tank is too full or if the vehicle overturns in the case of an acci­
dent.
- to allow the breathing of the fuel vapours towards the active charcoal filter;
- to allow the ventilation of the tank if there is a vacuum inside.
The valve consists of a float body (2), a heavy ball (3), a plate thrust against the valve body by a spring
(5) and a shim (8) thrust against the plate (4) by the spring (9). The operation of the multi-purpose
valve can be summed up in the following cases, depending on how full the fuel tank is:
a. if the tank is full, the float (2) shutters the port (1) preventing the liquid fuel from reaching the active
charcoal filter preventing it from being damaged;
b. jf the level of the fuel in the tank decreases, the float (2) goes down and rests on the ball (3) open­
ing the port (1); when the pressure exerted by the fuel vapours on the plate (4) overcomes the
spring (5) loading, a ring section opens between the actual plate and the valve body, allowing the
fuel vapours to come out of the duct (6) and reach the active charcoal filter;
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c. if the level of the fuel in the tank decreases to such an extent as to produce a vacuum inside the tank,
this acts on the shim (8) and, overcoming the spring (9) loading, recalls it downwards allowing the
ventilation of the tank through the port (7).
d. if the vehicle overturns, irrespective of how full the tank is, the ball (3), weighing down on the float
(2), pushes it against the port (1) preventing the escape of fuel which would be dangerous and cre
:
ate a fire hazard.
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