Fuel Systems; Gas Piping; Fuel Solenoid Valve; Fuel Regulators - Kohler 8.5RES Service Manual

6.12 Fuel Systems

WARNING
Explosive fuel vapors.
Can cause severe injury or death.
Use extreme care when handling,
storing, and using fuels.
The fuel supplier provides and maintains manual
shut-off valves and the primary regulator. Verify that the
fuel system capacity is adequate to supply the generator
set plus all other gas appliances.
A factory-installed secondary regulator and 12 VDC
solenoid valve are located in the front inlet air
compartment. The controller energizes the
solenoid valve to open at startup and deenergizes the
valve to close at shutdown.
regulator reduces fuel pressure for delivery to the fuel
metering valve. The fuel flows from the fuel metering
valve to the carburetor in a gaseous state.
carburetor mixes the fuel with intake air for consumption
by the engine.
Use a universal exhaust gas oxygen (UEGO) sensor to
check the fuel mixture after replacing the fuel regulator,
fuel mixer, or silencer. The engine should be warm when
the fuel mixture is checked. See Section 6.12.6 for
instructions to check the fuel mixture.
Refer to the troubleshooting
Section 3,Troubleshooting, to identify generator set
operation problems that may be caused by an
inadequate fuel supply, incorrect adjustments, or
damaged fuel system components.
instructions in this section to check fuel system
components.

6.12.1 Gas Piping

Verify that the gas pipe size meets the size
specifications in Figure 6-32. Measure the pipe length
from the gas utility pressure regulator to the end of the
pipe where it connects to the fuel inlet of the generator
set. Add 2.4 m (8 ft.) for each bend in the pipe.
Compare the total length with the chart in Figure 6-32. If
the piping is longer than the maximum length shown in
the chart, replace it with a larger pipe size. Bleed the air
from the gas lines after installation.
TP-6196 10/09
fuel
The secondary fuel
The
instructions in
Then use the
Figure 6-33 lists the maximum gas flow rates for each
model.
8.5RES
Natural
Pipe Length,
Gas
m (ft.)
8 (25) 3/4
15 (50) 3/4
30 (100) 1
46 (150) 1
61 (200) 1
Figure 6-32 Maximum Gas Pipe Length
Generator Set Model
8.5kW
12kW
Figure 6-33 Maximum Natural Gas Flow Rate

6.12.2 Fuel Solenoid Valve

A solenoid valve upstream of the regulator and the
flexible fuel connector provides automatic fuel on/off
control. The engine starting battery powers the solenoid
valve and the engine starting controls open the valve
when the engine cranks or runs.
Gas Valve Operation Test Procedure
1. Disconnect the positive (+) battery lead from the
gas valve terminal.
2. Apply 12 VDC to the gas valve terminal and listen
for an audible click, indicating that the valve
actuates.
3. Replace the gas valve if it does not actuate in
step 2.

6.12.3 Fuel Regulators

The typical gaseous fuel system uses two regulators.
The primary regulator reduces the line pressure to an
allowable inlet pressure for the secondary regulator.
The fuel supplier provides and maintains the primary
regulator. The secondary regulator is factory-installed
on the generator set and is designed for a maximum inlet
pressure of 2.7 kPa (6 oz./in.
column.
Note: Do not attempt to adjust the fuel mixture or engine
speed by adjusting the regulators.
Section 6 Component Testing and Adjustment
12RES
Natural
Gas
LP
1/2 3/4
3/4 1
1 1
1 1 1/4
1 1 1/4 1 1/4
Gas Flow Rate, Btu/hr.
Natural Gas LP
132000 180000
202000 270000
2
) or 280 mm (11 in.) water
LP
3/4
1
1
1
93