Figure 4-54.Fuel evaporization system.
FUELTANK VENTLINE carries fuel vapors up
Basic operation of a fuel evaporization control
to a charcoal canister in the engine compartment.
system is as follows:
CHARCOAL CANISTER stores fuel vapors
when the engine is NOT running. The metal or plastic
canister is filled with activated charcoal granules
capable of absorbing fuel vapors.
CARBURETOR VENT LINE connects the
carburetor fuel bowl with the charcoal canister. Bowl
vapors flow through this line and into the canister.
PURGE LINE is used for removing or cleaning
the stored vapors out of the charcoal canister. It
connects the canister and the engine intake manifold.
When the engine is running, intake manifold
vacuum acts on the purge line, causing fresh air to flow
through the filter at the bottom of the canister. The
incoming fresh air picks up the stored fuel vapors and
carries them through the purge line. The vapors enter
the intake manifold and are pulled into the combustion
chambers for burning.
When the engine is shut off, engine heat
produces excess vapors. These vapors flow through the
carburetor vent line and into the charcoal canister for
storage. The vapors that form in the tank flow through