Kohler Command PRO CH749, Service Manual

Page: 51 / 154

5.19
Section 5
EFI Fuel System
5
23. Reverse the appropriate procedures to install the
new injector(s) and reassemble the engine. Use
new O-rings and retaining clips any time an
injector is removed (new replacement injectors
include new O-rings and retaining clips).
Lubricate O-rings lightly with clean engine oil.
Use the installation tool provided with the
O-rings to install the new upper O-ring. Place the
tool into the fuel injector inlet. Place one side of
the O-ring into the O-ring groove and roll the
O-ring over the tool onto the fuel injector. Torque
the screw securing the fuel injector caps and
blower housing mounting screws to
7.3 N·m (65
in. lb.) , and the intake manifold and air cleaner
mounting screws to 10.5 N·m (93 in. lb.) . An ECU
Reset will need to be completed. Follow the
instructions on page 5.11.
Injector problems due to dirt or clogging are generally
unlikely due to the design of the injectors, the high
fuel pressure, and the detergent additives in the
gasoline. Symptoms that could be caused by dirty/
clogged injectors include rough idle, hesitation/
stumbling during acceleration, or triggering of fault
codes related to fuel delivery. Injector clogging
is usually caused by a buildup of deposits on the
director plate, restricting the
fl ow of fuel, resulting
in a poor spray pa tt ern. Some contributing factors
to injector clogging include higher than normal
operating temperatures, short operating intervals,
and dirty, incorrect, or poor quality fuel. Cleaning of
clogged injectors is not recommended; they should be
replaced. Additives and higher grades of fuel can be
used as a preventative measure if clogging has been a
problem.
Ignition System
Figure 5-16. Ignition Coil.
General
A high-voltage, solid-state, ba tt ery ignition system
is used with the EFI system. The ECU controls the
ignition output and timing through transistorized
control of the primary current delivered to the coils.
Based on input from the cranksha
ft position sensor,
the ECU determines the correct fi ring point for the
speed at which the engine is running. At the proper
instant, it interrupts the
fl ow of primary current in the
coil, causing the electromagnetic fl ux fi eld to collapse.
The fl ux collapse induces an instantaneous high
voltage in the coil secondary which is strong enough
to bridge the gap on the spark plug. Each coil
fi res
every other revolution.
Service
If a coil is determined to be faulty, replacement is
necessary. An ohmmeter may be used to test the
wiring and coil windings.
NOTE: Do not ground the coils with the ignition ON
as they may overheat or spark.
NOTE: Always disconnect the spark plug lead
from the spark plug before performing the
following tests.
Testing
1. Using an ohmmeter set on the Rx1 scale, check
the resistance in circuits as follows:
a. Disconnect the Black connector from the ECU
to check the number one cylinder coil (starter
side). Test between Black pin 1 and Black pin
15.
b. Disconnect the Grey connector from the ECU
to check the number two cylinder coil (oil
fi lter side). Test between Grey pin 10 and Grey
pin 17. A reading of 0.5-0.8

in each test
indicates that the wiring and coil primary
circuits are OK.
c. If reading(s) are not within speci fi ed range,
check and clean connections and retest.
d. If reading(s) are still not within the speci fi ed
range, test the coils separately from main
harness as follows:
1) Remove the screw retaining the coil to the
housing and disconnect the primary leads
connector.