33
Fuel System
22 690 01 Rev. --
KohlerEngines.com
Troubleshooting Smart-Choke
™
Related Causes
Condition
Possible Cause
Conclusion
Engine starts hard, runs rough, or
stalls at idle speed.
Choke not closing.
Check choke lever/linkage to ensure
choke is operating properly.
Check that bimetallic spring actuates
freely.
Engine runs rich (indicated by black,
sooty exhaust smoke, misfi ring, loss
of speed and power, governor
hunting, or excessive throttle
opening).
Choke partially closed during
operation.
Check choke lever/linkage to ensure
choke is operating properly.
Check that bimetallic spring actuates
freely.
Check choke diaphragm assembly
mounting.
Confi rm 12V to thermostat on top of
diaphragm assembly.
Confi rm check valve routing from
intake manifold to diaphragm
assembly is clear. Confi rm initial
pull-off of choke during cranking.
Smart-Choke
™
System Troubleshooting
These procedures are to be performed on a cold engine.
NOTE: Bimetallic spring assembly is pre-set at factory
and riveted shut. DO NOT attempt to adjust/
change its settings.
NOTE: Do not remove or loosen diaphragm screws on
diaphragm assembly. Position and torque is
pre-set at factory.
NOTE: Thermostat temperature must be at room
temperature before testing.
1. Turn knobs toward unlock symbol and remove air
cleaner cover. Lift and remove precleaner (if
equipped) and air cleaner element from air cleaner
adapter.
2. Remove blower housing.
3. Choke plate should be fully closed when engine is
cold.
4. There should be light spring tension holding choke
closed.
5. There should not be any binding when choke shaft
assembly is rotated, which could cause choke to
remain partially open.
6. Check choke linkage 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. 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.
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 infi nite (open) reading is found, replace
diaphragm assembly. Diaphragm vacuum signal will
not open choke plate fully when cold and will not
close choke plate fully when engine is warm.
9. Unplug check valve assembly from diaphragm and
draw a vacuum of -5 psig and confi rm that it holds
for at least 30 seconds. If it does not, replace
diaphragm assembly.
10. Confi rm check valve assembly is oriented correctly
and that it fl ows easily in one direction – toward
manifold.
11. Reinstall blower housing.
12. 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.
13. With engine running, 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.
