VESPA 946 E4 EMEA 2021 Manual page 67

Vespa 946 E4-E5 EMEA-USA-ASIA (2021-)
To ensure that the engine works properly, it is necessary that the flow of air is not too intense, this is
achieved by means of a restricted section 0.0354in (0.9 mm) formed in the socket on the intake manifold.
The relative connecting pipe with the canister, includes the installation of the safety valve.
This is a one-way valve which ensures the passage of air in the direction of the manifold when the
control vacuum is greater than 2.9PSI (20kPa) (200mbar).
The vacuum of the engine at idle, causes a slight flow of air easily compensated by the idle speed
adjustment parameters.
When the vehicle is stopped, the safety valve will be closed due to the lack of control vacuum therefore,
any expansion of the fuel tank, will not cause pollution of the intake manifold, and then cause flooding
of the engine.
To control the valve, it is preferable to it, alterna-
tively just access the manifold side pipe.
•
Connect the MITY-VAC pump on the
engine side duct.
•
Select the pump command on the "vac-
uum" position, then slowly apply vac-
uum up to the valve threshold check
opening.
If you detect different pressures, replace the valve.
Note: An excessively high opening vacuum value
impedes the active carbon regeneration process;
vice versa, an opening vacuum that is too low, in-
creases the flow of air to the engine causing the
thinning of idle.
Characteristic
Standard opening vacuum
(2.90-3.77)PSI (20-26)kPa (200-260)mbar
Roll-over valve check
The valve must enable the following results:
•
Aeration of the tank while riding (the ambient air enters the tank in relation to the volume of
fuel used).
•
Pressurisation of the tank (while riding or during a break, you may experience increases in
the temperature inside the tank. The valve must pressurize the tank to limit the escape of
fuel vapour to the canister).
Maintenance
MAIN - 67