Fuel System
3932 690 03 Rev. N
KohlerEngines.com
Smart-Choke
™
System Troubleshooting
Original Design Smart-Choke
™
System Oil
Pressure Switch
B
A
A Power In Terminal
B Power Out Terminal
These procedures are to be performed on a cold engine.
NOTE: Bimetallic spring assembly is pre-set at factory.
DO NOT attempt to adjust/change its settings.
NOTE: Do not remove or loosen thermostat screws.
Position is set at factory.
NOTE: Thermostat temperature must be at room
temperature before testing.
1. Remove air cleaner cover, and air cleaner from air
cleaner base.
2. Choke plate should be fully closed when engine is
cold.
3. There should be light spring tension holding choke
closed.
4. There should not be any binding when choke shaft
assembly is rotated, which could cause choke to
remain partially open.
5. Remove blower housing.
6. Check choke linkage and air vane deector
assembly for binding or debris build up. Gently
actuate linkage and observe that choke plate has full
range of movement (open and close).
7. Unplug red wire with black tracer power lead of
bimetallic spring assembly. Measure heat circuit
resistance of choke thermostat assembly, with a volt
ohm meter at room temperature (68°F/20°C).
8. Original Design Smart-Choke
™
System: Attach one
wire of meter to red wire w/yellow tracer terminal of
assembly, and other wire to ground of bracket or to
ground strip of assembly body.
Updated Design Smart-Choke ™ System: Attach
one wire of meter to red wire w/black tracer terminal
of assembly, and other wire to ground of bracket or
to ground strip of assembly body."
Thermostat resistance should read 15 ohms (+/- 10
ohms). If assembly is warm, allow unit to cool to
room temperature (68°F/20°C) for accurate testing.
If an innite (open) reading is found, replace
bimetallic spring choke bracket assembly. Air vane
linkage will not open choke plate fully when cold and
will not close choke plate fully when engine is warm.
9. Reinstall blower housing.
10. Start engine. Upon start up, choke plate should be
1/3 closed. Choke plate should gradually change to
full open position after 2 to 2-1/2 minutes of running.
This action is performed by bimetallic spring
assembly being heated. If choke plate fails to open,
recheck linkage for binding.
11. With engine running (Original Design Smart-
Choke
™
System) or key switch ON (Updated Design
Smart-Choke
™
System), check voltage at bimetallic
spring choke bracket assembly. Using a DVOM,
attach black lead of meter to ground screw on
assembly bracket, and red lead of meter to red wire
w/black tracer.
12. Select DC VOLTS on your meter. You should see a
minimum of 12 volts DC.
If no voltage is present, test for voltage at oil
pressure switch (Original Design Smart-Choke
™
System).
If voltage is present at power in terminal but not at
power out terminal when engine is running, pressure
switch is potentially faulty. Remove switch and install
a pressure test gauge and start engine. Consult
troubleshooting section of this manual for oil
pressure testing instructions. If adequate pressure is
found, replace pressure switch and conrm
operation/voltage readings.
13. If linkage is free and choke plate fails to open fully
after 2 minutes, check spring tension of bimetallic
assembly. If necessary, replace bimetallic spring
choke bracket assembly.
14. Reinstall air cleaner element and secure cover.
Thermostat
Different styles of thermostats are used. Identify style
on engine and follow appropriate procedure to reset or
install.
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