Pressurizing The Tank; Seal In The Case Of Overturning - Fiat 1998 Marea Service Manual

Engine
Fuel system
10.
The valve is supported by a steel plate and opposed by a spring.
When the pressure in the tank exceeds the recommended value, it overcomes the resistance of the spring
allows the valve to lift, thereby allow the flow of vapours.
When the pressure returns to within the limits, the valve closes again.
Ventilation
In certain operating conditions, a vacuum may form in the tank through the effect of:
- heat variations;
- fuel consumption.
The function of the valve, under these circumstances, is to restore the pressure inside the tank through the
intake of air.
Any problem with this function can cause irregular operation or the breakdown of the vehicle through
problems with the electric pump supply.

Seal in the case of overturning

The roll-over function is to prevent the escape of fuel from the tank if the vehicle overturns or is at a very
steep angle.
During the normal operation of the vehicle (bends, acceleration, braking, etc.) the fuel is shaken around in
the tank and may spill out.
The high sensitivity of this valve to roll-over prevents these escape.
SUPPLY MANIFOLD (RAIL)
The supply manifold (rail) is fitted on the cylinder head, inlet side.
With its volume it dampens the pressure fluctuations of the fuel due mainly:
- to the operation of the pressure pump;
- to the opening of the injectors.
The fuel pressure sensor is fitted in the centre of the supply manifold.
The (high pressure) hydraulic connections are achieved through special steel pipes.
20
Marea- Marea Weekend
~ I MULTI-PURPOSE VALVE
The multi-purpose valve is Icoated on the fuel
tank and carries out the following tasks:

- pressurizing the tank

- ventilation
- seal in case of overturning
Pressurizing the tank
The tank pressure is kept at between 55 and 75
mbar by means of a valve resting on a sealing
edge.
< § ! > ^9 ™
99 range
Print n° 506.763/74