Opel 1900 1973, Service Manual, Page: 328 / 625

FUEL SYSTEM
37
must always be removed before the distributor can be
removed.
EVAPORATION CONTROL SYSTEM
1. The function of the fuel evaporation control sys-
tem is to absorb the fuel vapors developing in the fuel
tank, especially when vehicle is parked, due to at-
mospheric pressure and temperature influences, and
to release these fuel vapors during vehicle operation.
2. This system utilizes the property of the activated
carbon to absorb and expel fuel vapors. The activated
carbon container is installed on the left front side of
the engine compartment. The fuel tank has a
vented tiller cap. Vent hoses are joined in the area of
the tank. A plastic evaporation line leads from there
along vehicle underbody to the activated carbon con-
tainer.
3. A small tube above the throttle valve body con-
nects the carburetor to the activated carbon con-
tainer. In this way, the fuel vapor collected in the
activated carbon container is fed through the
carbu-
retor into the combustion chambers during engine
operation.
4. The carburetor is provided with an internal and
outside ventilation, the activated carbon container is
also connected to the outside ventilation (only effec-
tive when engine is idling). In this way, the fuel
vapors escaping to the outside during engine idle are
collected
by
the activated carbon container and fed
into the combustion chambers.
5. The vent lines are connected to the upper part of
the activated carbon container. Fresh air enters
through a foam rubber
at the lower part and
flows, together with the fuel vapor, to the carburetor.
Metered bores in the hose fittings of the fuel tank
control the air and fuel vapor flow through the
activated carbon container to the carburetor, and the
pressure release in the fuel tank and ensure complete
purging of the carbon container.
Care must be taken not to mix up lines at the ac-
tivated carbon container. See Figure
6. The metered bores in the fuel tank fitting and an
overflow protection in the fuel tank, which prevents
a complete filling of the tank, prevents fuel flows into
the activated carbon container rendering it useless.
FUEL FILTER
An AC fuel filter type (GF 423) is being used on all
1973 A vapor return line returns vapors in the
fuel line back to the fuel tank. Proper installation of
the filter is essential. The vapor return line connector
must be on top (highest point) for proper operation.
See Figure
1. LINE TO
CARBURETOR
2. FILTER
3.
LINE FROM
4. VAPOR
RETURN LINE
Figure Fuel Filter
MAINTENANCE AND ADJUSTMENTS
Figure Carbon Canister
CLEANING FUEL PUMP STRAINER