Float valve (page 2 of 2)

The solenoid valve is connected to a positive (+ BATT.) and to terminal 29 of the control unit which operates it.

The operation of the solenoid valve is designed to control the quantity of fuel vapours drawn in by the filter and recirculated to the inlet (under the butterfly valve).

The valve enclosed in the casing (1) is made up of a moving part or shutter (2) connected to a spring (3); the fixed part is composed of a metal cylinder (4) perforated inside with a coil (5).

When the ignition coil is supplied, the shutter (2) is attracted against the cylinder (4) and the solenoid valve closes.

The opening and the closing of the solenoid valve is achieved by means of a special square wave signal, produced by the injection control unit (duty-cycle operation).

The signal is produced on the basis of the butterfly valve opening angle and is only activated at a given engine temperature, established during the setting up.

When the key is turned to the ON position, the valve receives a fixed supply of 12 V so that it remains closed; this also continues during the starting and post-starting stages. Whilst the engine is warming up, irrespective of its speed, the control unit activates the working cycle and maintains it until the temperature of the engine coolant reaches 70° - 80° C.