6-2
CAUTION
If the genset fuel line is con-
nected to the main fuel line with a tee, the
genset may starve for fuel when the vehicle
is operated at highway speeds. The genset
fuel pump has neither the capacity nor the
power to overcome the draw of the vehicle
engine fuel pump. For this reason, use a
separate fuel line to the genset, or a sepa-
rate fuel tank.
• Tying a genset fuel line into a pressure supply
line (vehicle fuel pump at the engine side of the
fuel pump) may cause poor genset operation
and create a hazard of fire or explosion caused
by fuel leakage.
WARNING
Gasoline presents the hazard
of explosion or fire, which can result in se-
vere personal injury or death. Do not con-
nect the genset fuel line to the pressurized
part of the vehicle fuel system. Flooding of
the genset engine and compartment with
gasoline can occur, resulting in a fire haz-
ard.
Some vehicle manufacturers permit tying into the
fuel
return line
on high pressure fuel systems. Con-
tact the vehicle manufacturer for details and ap-
proval.
Install an approved, flexible, non-metallic, non-con-
ductive, and non-organic fuel line between the ve-
hicle fuel system and the genset, to absorb vibra-
tion. The flexible fuel line must be long enough to al-
low genset movement, to prevent binding, stretch-
ing, or breaking. Onan recommends seamless steel
tubing and flared connections for long runs between
the fuel tank and the flexible connector to the gen-
set.
Run fuel lines at the same height as the top level of
the tank to a point as close to the engine as pos-
sible. This reduces the danger of fuel siphoning out
of the tank if the line should break.
Keep fuel lines away from hot engine or exhaust
areas to reduce the chance of vapor lock. Fuel lines
should be accessible and protected from damage.
Use metal straps without sharp edges to secure fuel
lines. Do not run fuel lines where they may contact
sharp or rough surfaces, or where they may be-
come kinked, pinched, chaffed, or struck.
PROPANE (LPG) FUEL SYSTEM
Fuel System Provisions
Onan LPG gensets contain a filter cartridge and
magnet connected to the fuel solenoid valve to pro-
tect the solenoid valve and regulator valves from
dirt and contaminants. The solenoid valve and filter
are shown in Figure 6-1. Figure 6-2 on Page 6-3
shows the flow diagram for the LPG fuel system
components used on the genset.
Genset operation using LPG is very sensitive to alti-
tude, temperature, and BTU content of the gas.
Variation in any one of these factors directly affects
the performance on the genset. Because of this, mi-
nor adjustments might be required after the installa-
tion. Refer to the Generator Set Service Manual if
adjustments are required.
Recommended Fuel
Use clean, fresh commercial propane or HD-5
grade liquid propane gas in a mixture of at least 90
percent propane. Propane fuels other than HD-5
grade can contain more than 2.5 percent butane
and can result in poor fuel vaporization and poor en-
gine starting in low ambient temperatures (below
32F or 0C).
FIGURE 6-1. FUEL SOLENOID VALVE AND FILTER
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