Multi-purpose valve

MULTI-PURPOSE VALVE

The multi-purpose valve is located on the fuel tank and carries out the following tasks:

• pressurizing the tank
• ventilation
• seal in case of overturn

Pressurizing the tank

The tank pressure is kept at between 55 and 75 mbar through a small valve resting on the edge.

This valve is supported by a steel plate and has an opposing spring.

When the pressure in the tank exceeds the recommended value, it overcomes the resistance of the spring and allows the valve to rise, allowing the flow of vapours.

When the pressure returns to within the limits, the valve closes.

Ventilation

In certain operating conditions, a vacuum may be created in the tank due to:

• heat variations;
• fuel consumption.

The function of the valve, in this case, is to restore the pressure inside the tank by drawing in air.

Any irregularity in this function can cause misfiring or the vehicle to come to a halt through problems with the supply of the electric pump.

Seal in the case of overturning (roll-over)

The roll-over function is designed to prevent fuel coming out of the tank if the vehicle turns over or is at an angle.

During normal operation (round bends, acceleration, braking, etc.) the fuel splashes around in the tank and could escape.

The extreme sensitivity of this valve to roll-over prevents fuel from escaping.

SUPPLY MANIFOLD (RAIL)

The supply manifold (rail) is fitted on the cylinder head, inlet side.

It dampens the fuel pressure fluctuations due mainly to the:

• operation of the pressure pump;
• opening of the injectors.

The fuel pressure sensor is fitted in the centre of the supply manifold.

The (high pressure) hydraulic connections are through special steel pipes.