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TP-6200 10/12 143Section 3 Scheduled Maintenance
SB-700
1. Electronic-controlled pressure regulator (EPR)
2. Fuel mixer
3. Fuel solenoid valve
(UL--listed models require 2 fuel solenoid valves)
1
2
3
Figure 3-8 Fuel Regulator and Valve, Typical
3.6.3 Natural Gas and LPG Conversion
Most models operate on either natural gas or LPG fuel
by performing the fuel conversion procedure. A hang
tag on the fuel regulator may provide additional
conversion setup information. Fuel conversion may
decrease generator set output. Refer to the respective
generator set spec sheet for ratings based on fuel
selection. Changing fuel does not alter the emissions
compliance of the generator set engine. Consult your
local generator set distributor/dealer for additional
information.
Note: If a gas-fueled model has the fuel type changed
(LPG to natural gas or
natural gas to LPG), order
a new nameplate from an authorized distributor/
dealer with the updated ratings and attach to the
generator set.
To change the fuel type, change the electrical
connections between the fuel system and the engine
ECM. The engine ECM has fuel tables and spark
advance curves programmed for both natural gas and
LPG. The information shown below, in Figure 3-9, and in
Figure 3-10 generally apply to all models and all fuels.
Be sure to review the respective wiring diagram for your
specific model for possible special applications.
Natural Gas Operation
D Disconnect lead 65 from lead N5.
D Disconnect lead 73B from the fuel solenoid valve.
D Connect lead 73A to the fuel solenoid valve.
LPG Vapor Operation
D Disconnect lead 73A from the fuel solenoid valve.
D Connect lead 73B to the fuel solenoid valve (LPG
vapor).
D Connect lead 65 to lead N5 (ground).
LPG Liquid Withdrawal Operation
D Disconnect lead 73A from the fuel solenoid valve.
D Connect lead 73B to the fuel solenoid valve (LPG
liquid withdrawal).
D Connect lead 65 to lead N5 (ground).
Auto Changeover Natural Gas/LPG Vapor
Operation
D Disconnect lead 65 from N5.
D Connect lead N5 to LFP2 relay common terminal.
D Connect lead 73A to the fuel solenoid valve (natural
gas).
D Connect lead 73B to the fuel solenoid valve (LPG
vapor).
Eng.
ECM
Natural
Gas
LPG
Vapor
LPG
Liquid
Auto
Changeover
73A
QCON--7
(NG fuel
solenoid
valve)
not used
QCON--7
(NG fuel
solenoid valve)
N5 not used 65 65 LFP2--COM
73B not used QCON--10 (LPG fuel solenoid valve)
65 not used N5 N5 not used
63 LFP1--NC low fuel pressure sensor (if used)
70E2 P6--B (15 amp fuse)
Figure 3-9 Gas Fuel Electrical Connections
3.6.4 Fuel System Changeover Kits
(Dual Fuel)
Automatic Changeover
A changeover fuel system kit provides automatic
changeover from natural gas to LPG vapor. The
primary and backup fuels each have a fuel solenoid
valve. The primary fuel is natural gas; the backup fuel is
LPG vapor. Before starting, both fuel solenoid valves
are closed. When the generator set starts, the primary
fuel solenoid valve opens. The primary fuel line has a
pressure switch in series with a relay connected to the
start/run circuit.
When the primary fuel pressure drops below 0.6 kPa
(1.4 oz./in.
2
) or 6.4 cm (2.5 in.) water column , a relay
opens the backup fuel solenoid valve and closes the
primary fuel solenoid valve. When the primary fuel
pressure rises above 0.6 kPa (1.4 oz./in.
2
)or6.4cm
(2.5 in.) water column, the generator set uses the
primary fuel. Contact an authorized service
distributor/dealer for kit availability.