Fiat 1996 Brava Service Manual page 454

Engine
Fuel system
10.
Bravo-Brava ^ 16v
'98 range
MULTI-FUNCTION VALVE (SIRIO 0175.00)
This valve is used for carrying out various functions, such as:
- prevent the passage of liquid fuel, when the tank is too full or if the vehicle overturns in an accident;
- permit the venting of fuel vapours towards the activated charcoal filter;
- permit ventilation of the tank if it contains a vacuum.
The valve consists of a float (2), a heavy ball (3), a plate (4) pushed home against the valve body by the
spring (5), a shim (8) pushed home against the plate (4) by the spring (9). The operation of the multi­
function valve may be summarized in the following cases, depending on how full the fuel tank is:
b.
if the tank is full, the float (2) blocks the hole (1), preventing the liquid fuel from reaching the activat­
ed charcoal filter, thus preventing damage to the latter;
if the fuel level falls, the float (2) descends and rests on the ball (3), opening the hole (1); when the
pressure exerted by the fuel vapours on the plate (4) exceeds the load of the spring (5), a
ring-shaped gap opens between the plate and the valve casing, which allows the fuel vapours to
emerge from the pipe (6) and reach the activated charcoal filter;
c. if the reduction in fuel level in the tank is such that it creates a vacuum in the tank, this vacuum acts
on the plate (8) and, overcoming the load on the spring (9), recalls it downwards, allowing the tank
to ventilate through the hole (7);
d. if the vehicle overturns, however full the tank is, the ball (3), weighing down on the float (2), pushes
the latter against the hole (1), preventing dangerous leakage of fuel and resulting risk of fire.
42
Publication no. 506.670/14