C-6 and Manual Transmission

The Evaporative Emission Control (EVAP) system is designed to prevent fuel vapors from being emitted into the atmosphere from a vehicles fuel system. In order to meet Federal and State Regulations for vehicle evaporative emission control, all gasoline powered engines are required to be equipped with this system.
The EVAP system consists of a fuel tank pressure/vacuum filler cap, a fuel tank vapor vent valve, a charcoal "carbon" canister, and a canister purging control device.
The EVAP system directs fuel vapors generated in the fuel tank through the vapor valve to a charcoal carbon canister. Activated charcoal within the canister holds and stores the fuel vapors, until they are purged into the induction system.

Typical Ported Purge Evaporative Emission System:

As the throttle plate is moved past the idle position, a port within the throttle body is exposed. This allows ported vacuum to be applied to the canister. The stored fuel vapors are then drawn into the induction system to be consumed. A vacuum restrictor is usually inserted within the vacuum line between the manifold and the canister for regulating purge operation.