Onan CCK Service Manual

MAIN POWER
FIGURE 26. VAPOR WITHDRAWAL FUEL SYSTEM, BLOCK DIAGRAM
LPG VAPOR WITHDRAWAL SYSTEM
A typical vapor withdrawal LP gas fuel system
consists of a vacuum fuelock and filter, a fuel
regulator, and a gas carburetor connected by flexible
hoses, Figure 26. A pulse balance line is needed for
one and two cylinder engines between the carburetor
and regulator. A vacuum line is needed between the
intake manifold and the fuelock and filter. Some
systems have a vacuum or solenoid operated fuel
cutoff valve or both; the solenoid operated valve may
be tied in with the ignition system.
FUEL
The engine and carburetor operate on propane
(Liquified Petroleum Gas-LPG). This discussion
covers only systems and components used with
propane vapor withdrawal applications.
FUELOCK AND FILTER
The IMPCO vacuum operated fuelock and filter is
combined in one unit. Figure 27. It should be trouble-
free and maintenance-free for extended periods.
Normally, no adjustments or filter replacements are
needed on a periodic basis, but repair kits and
replacement filters are available for complete
overhaul if a malfunction occurs. Each kit includes
detailed and illustrated installation procedures and
new replacement parts.
FIGURE 27. FUELOCK AND FILTER
The fuel inlet and outlet take 1/4~inch NPT fittings.
The vacuum connection takes a 1/8-inch NPT fitting
for a 7/32-inch I.D. hose. The fuelock opens with 2-
inches water column at normal tank pressure.
The fuelock and filter unit replaces a separate line
filter, an electric solenoid lockoff valve and a vacuum
controlled switch required on earlier gas engine
applications.
32

Onan CCK Specifications

General

Cylinders	2
Ignition System	Battery ignition
Fuel Type	Gasoline
Cooling System	Air-cooled
Fuel System	Carburetor
Starter	Electric
Governor	Mechanical
Max RPM	1800 RPM
Engine Type	4-cycle
Bore and Stroke	3.25 x 3.625 inches (82.55 x 92.08 mm)