(1747) 16v

(1747) 16v

The anti-evaporation system is designed to prevent fuel vapours, comprising the lightest particles of hydrocarbons, which basically form in the tank, from being discharged into the atmosphere.

The system consists of the tank, the vapour separator, two float valves, a two-way ventilation valve, the charcoal filter and a charcoal filter solenoid valve, operated by the control unit. The cap contains a two-way safety valve.

Operating principle

The system operates, especially at high outside temperatures, when the temperature of the fuel increases and, as a result, the tendency to evaporation increases: in this situation, the pressure inside the tank increases.

In particular, even with the tank (1) full, the two float valves (3) remain open as they are positioned higher than the breather pipe and therefore always allow the fuel vapours to reach the separator (2), thereby preventing fuel from escaping.

The fuel vapours reach the charcoal filter (6) when the pressure inside the tank causes the opening of the ventilation valve (8). This valve also allows an intake of air into the tank via the charcoal filter if it proves necessary when the level of the fuel decreases.

When the engine is running, the control unit operates the charcoal filter solenoid valve which allows the intake of vapours by the engine and the consequent scavenging of the charcoal filter.

If, as a result of the malfunction of one of the components, the pressure inside the tank increases to dangerous levels, the safety valve, located in the cap (4), allows the pressure to be discharged outwards. If necessary, this valve can open in the opposite direction to ventilate the tank and prevent the vacuum from becoming too great.

1. Fuel tank
2. Vapour separator
3. Float valve
4. Plug with safety valve
5. Engine management control unit
6. Charcoal filter
7. Charcoal filter solenoid valve
8. Safety and ventilation valve
9. Intake manifold
10. System relay feed