Kohler K91 Service Manual page 51

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Two Stage Regulator
The two stage regulator used on Kohler engines is
a double diaphragm type regulator designed for
use with air-cooled engines. It combines primary
and secondary regulation in one unit . The regula­
tor fuel inlet is connected to the fuel tank. Its out­
let is connected t o the carburetor. If the regulator
fails to operate properly, replace it or have it serv­
iced by an a uthorized gas equipment shop . Never
attempt to service a faulty regulator.
Vaporized fuel is admitted to the regulator at fuel
tank pressure (up to 250 psi) . Because the secon­
dary valve is closed (engine not running) , the
pressure on the internal side of the primary dia­
phragm builds up until t he pressure overcomes the
spring action on the opposite side of the d ia­
phrag m . This primary diaphragm spring has suffi-
Figure 6-37. Typical Primary Regulator.
cient tension t o require approximately 1 0 psi pres­
sure on the internal side of the diaphragm to
counteract the opening force due to the spring .
When the pressure reaches this leve l , the valve is
close d , preventing further pressure rise .
The secondary diaphragm acts against the secon­
dary valve spring. Its action results from vacuum
caused by the carburetor. As the vacuum begins
acting on the d iaphrag m , the diaphragm is moved
nearer to the center of the regulator , opening the
secondary valve u ntil equilibrium is reached. As
more fuel is needed , vacuum from the carburetor
increases , causing the secondary valve to open
further. When fuel is flowing , pressure on the pri­
mary diaphragm is lowered slightly , permitting the
spring to open the primary valve i n an attempt to
bring the pressure back to 1 0 psi . Refer to Figure
6-38.
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REGULATOR COVER
DIAPHRAGM
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