Suzuki GS850G Service Manual page 336

FUEL COCK
$2
Fuel valve
[ z ?
O-ring
13? Diaphragm
(42 Spring : 5 :
One
way
valve
(& Fuel flow
Bt
Vacuum
When the engine is not running with the valve in
@
the ON position, the fuel valve i s kept in the
closed position by applying pressure utilizing a
spring
so
that no fuel will flow to the carbure.
tars. When the engine is engaged,
a negative
pressure is generated in the diaphragm chamber
through the vacuum (negative pressure)
pipe which is connected to
the carburetors, and
builds
up
a negative pressure which
i s higher
than the spring pressure
so
that the diaphragm is
forced to open the fuel valve and thus allow
the
fuel t o flow to
the carburetors.
On the other hand, setting the valve
in
the ON
position keeps the air return orifice open.
Negative pressure does not accumulate on the
diaphragm a t the time of engine stopping, and
then the spring pressure actuates the diaphragm
to move back t o its original posirion and closes
the fuel valve.
However, setting the valve in PRI position with
a screwdriver causes the air return orifice to
close, resulting in negative pressure in the
chamber under
the diaphragm. This nega-
tive pressure doesn't allow the fuel valve to
close and therefore the fuel keeps flowing to the
carburetors,
PRI
When starting the engine
at
PRI
position,
be sure to change the valve from PRI