30 Generac®Power Systems, Inc.
The greater the airflow through the carburetor venturi,
the lower the pressure at the venturi throat. The lower
the pressure at the venturi throat, the greater the
diaphragm movement, and the greater the movement of
the regulator valve. The more the regulator valve opens,
the greater the gas flow that is proportional to airflow
through the generator.
The following facts about the secondary regulator must
be emphasized:
• The regulator must be sensitive to venturi throat
pressure changes throughout the operating range.
• The regulator must be properly adjusted so it will
stop the flow of gas when the engine is not running
(no air flow through the carburetor).
• The slightest airflow (and vacuum in the venturi
throat) should move the regulator valve off its seat
and permit gas to flow.

6.5.6 FUEL SU PPLY LI NES

• LP gas lines must be accessible, but protected against
possible damage.
• Do NOT connect electrical wiring to any LP gas fuel
line or run wiring alongside the lines.
• Route gas lines away from hot engine exhausts.
• Retain gas lines with metal clamps that do not have
sharp edges.
• Install an approved length of flexible hose between
the gaseous fuel solenoid valve and rigid fuel supply
lines. The flexible line must be nonmetallic, non-
organic and nonconductive. It must be approved for
use with LP gas.

6.5.7 EXCESS FLOW VALVE

LP gas tanks should have an excess flow valve, accord-
ing to NFPA 501C, Paragraph 3-4.4. This valve and the
gas lines must be carefully sized so the valve will close
when a fuel line is severed or broken. Consult the
Natural-LP Gas Association for information and limita-
tions of excess flow valves.
Manual shutoff valves on the supply tank and elsewhere
in the system must be fully open when operating the
generator. The excess flow valve functions properly only
if all valves are fully open.

6.5.8 LEAKAGE TESTS

Do not place the generator into service until you have
properly tested the gas system for leaks. To test the sys-
tem, you need a separate source of 12 volts DC to open
the gaseous fuel solenoid valve.
The leak test must comply fully with NFPA, Paragraph
318. All connections, hoses, valve regulators, fittings,
and other fuel system parts must be tested under gas or
air pressure of not less than 90 psi (620 kPa), while
using soap and water or an equivalent solution to check
for leaks. Other approved methods of testing for leaks
may be used, if appropriate. DO NOT USE ANY FLAME
TO TEST FOR LEAKS.
Gaseous fuel lines between the tank and the sec-
ondary regulator are under a positive pressure
(about 11 inches water column). Gas pressure at
the outlet side of the secondary regulator, howev-
er, is a negative pressure and can draw flame
inside a line or fitting and cause an explosion.
6.6 EXHAUST SYSTEM
The generator exhaust system must be safely and prop-
erly installed. Only approved mufflers and other
exhaust system parts must be used. A properly installed
exhaust system must be vapor tight, quiet and com-
pletely safe.
The generator engine gives off DEADLY carbon
monoxide gas through its exhaust system. This
dangerous gas, if breathed in sufficient concentra-
tions, can cause unconsciousness or even death.
Never operate the generator set with the vehicle
inside any garage or other enclosed area. DO NOT
OPERATE THE GENERATOR IF THE EXHAUST SYS-
TEM IS LEAKING OR HAS BEEN DAMAGED. SYMP-
TOMS OF CARBON MONOXIDE POISONING ARE
(a) inability to think coherently; (b) vomiting; (c)
twitching muscles; (d) throbbing temples; (e)
dizziness; (f) headaches; (g) weakness; and (h)
sleepiness. IF YOU FEEL ANY OF THESE SYMP-
TOMS, MOVE INTO FRESH AIR IMMEDIATELY. IF
SYMPTOMS PERSIST, GET MEDICAL HELP. Do not
operate the generator until its exhaust system has
been inspected and properly repaired.
Never tee the generator engine exhaust pipe into
the vehicle engine exhaust piping. This causes
excessive back pressure on the generator engine.
Also, water from one engine can damage the
other engine.
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Section 6 – Installation
PRIMEPACT 55G and 55LP Recreational Vehicle Generators