Fuel Vapour Cut-Off Solenoid (Ec1); Longitudinal Section Of Fuel Vapour Cut-Off Valve - Fiat Bravo Service Manual

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Fuel vapour cut-off solenoid (EC1)

The function of this valve is to control, via the fuel injection-ignition electronic control unit, the quantity

of fuel vapours drawn in by the activated charcoal filter and directed to the inlet manifold.

If there is no supply, this valve is in the closed position, preventing the fuel vapours from making the

mixture excessively rich.

Its operation is controlled by the electronic fuel injection-ignition as follows:

- during starting, the solenoid remains closed, preventing the fuel vapours from making the mixture too

rich; this condition remains until the coolant reaches a pre-established temperature (about 65 °C)

- with the engine up to temperature, the electronic control unit sends a square-wave signal to the

solenoid, which modulates aperture depending on the full/empty ratio of the signal.

In this way the control unit controls the quantity of fuel vapours sent to the inlet manifold, thus avoid-

ing significant changes in mixture strength.

In the operating conditions listed below:

- throttle in idle position

- engine speed below 1500 rpm

- bottom inlet manifold pressure at a limit value calculated by the

control unit in accordance with the rpm

the solenoid control is inhibited, and the solenoid is kept in the

closed position, to improve engine operation.

Counter spring.

Magnetic winding.

Pipe connected to inlet manifold.

Pipe connected to activated charcoal filter.

Wiring connector

The numbers in boxes indicate the corre-

sponding control unit pins.

Solenoid control is inhibited.

Self-adaptivity of fuel vapour recirculation is

Self-adaptivity of mixture strength is inhibited.

Checking the resistance

The solenoid's resistance can be measured by

disconnecting the connector and connecting

an ohmmeter as s h o w n in the figure.

Resistance: 17.5 - 23.5 ohm to 20 C