Fuel Conversion Connections - Kohler APM402 Operation

3.6.5

Fuel Conversion Connections

To change the fuel type, change the wiring harness connections. The engine ECM has fuel tables and spark advance curves
programmed for both natural gas and LPG. Use the following fuel connection tables and wiring diagrams to determine the
applicable connections for your generator set model. Be sure to review the wiring diagram for special applications.
For typical models with PSI and GM engines, use the following:
See Figure 33 and Figure 34.
Natural Gas Operation

Disconnect lead 65 from lead N5.

Disconnect lead 73B from the fuel solenoid valve.

Connect lead 73A to the fuel solenoid valve.
LPG Vapor Operation

Disconnect lead 73A from the fuel solenoid valve.

Connect lead 73B to the fuel solenoid valve (LPG vapor).

Connect lead 65 to lead N5 (ground).
LPG Liquid Withdrawal Operation

Disconnect lead 73A from the fuel solenoid valve.

Connect lead 73B to the fuel solenoid valve (LPG liquid withdrawal).

Connect lead 65 to lead N5 (ground).
Auto Changeover Natural Gas/LPG Vapor Operation

Disconnect lead 65 from N5.

Connect lead N5 to LFP2 relay common terminal.

Connect lead 73A to the fuel solenoid valve (natural gas).

Connect lead 73B to the fuel solenoid valve (LPG vapor).
Harness Natural Gas
73A QCON-7
(NG fuel solenoid valve)
N5 not used
73B not used
65 not used
63
70E2
Figure 33 Gaseous Fuel Electrical Connections, Typical Models with PSI or GM Engine
86
LPG Vapor LPG Liquid
not used
65
QCON-10 (LPG fuel solenoid valve)
N5
LFP1-NC low fuel pressure sensor (if used)
P6- B (15 amp fuse)
Auto Changeover
QCON-7
(NG fuel solenoid valve)
65 LFP2-COM
N5 not used
TP-6694 9/20