Kohler COMMAND CH18, Service Manual

Page: 92 / 232

5B.23
Section 5B
EFI Fuel System
5B
For starting and warm up, the ECU will adjust the
fuel and ignition timing, based upon ambient
temperature, engine temperature, and loads present.
In cold conditions, the idle speed will probably be
higher than normal for a few moments. Under other
conditions, the idle speed may actually start lower
than normal, but gradually increase to the established
setting as operation continues.
Do not attempt to
circumvent this warm up period, or readjust the idle
speed during this time. The engine must be completely
warmed up for accurate idle speed adjustment.
Adjustment Procedure
1. Make sure there are no fault codes present in the
ECU memory.
2. Start the engine and allow it to fully warm up
and establish closed looped operation
(approximately 5-10 min.).
3. Place the throttle control in the ‘‘idle/slow’’
position and check the idle speed with a
tachometer. Turn the idle speed screw in or out as
required to obtain
1500 RPM , or the idle speed
specified by the equipment manufacturer.
4. The low idle speed adjustment can affect the high
speed setting. Move the throttle control to the full
throttle position and check the high speed. Adjust
as necessary to 3750 RPM (no load), or the speed
specified by the equipment manufacturer.
Idle Speed Screw Dampening Spring
A small dampening spring (Kohler Part No.
24 089 42-S ) is attached to the end of the idle speed
screw of some EFI engines to help stabilize no load
operating speeds. See Figure 5B-36.
Figure 5B-35. Upper Intake Manifold.
General
The EFI engines have no carburetor, so the throttle
function (regulate incoming combustion airflow) is
incorporated in the intake manifold assembly. The
manifold consists of a one-piece aluminum casting
which also provides mounting for the fuel injectors,
throttle position sensor, fuel rail, air baffle, idle speed
screw, and air cleaner assembly.
Service
The throttle body/intake manifold is serviced as an
assembly, with the throttle shaft, throttle plates, and
idle speed adjusting screw installed. The throttle shaft
rotates on needle bearings (non-serviceable), capped
with rubber seals to prevent air leaks.
Idle Speed Adjustment (RPM)
General
The idle speed is the only adjustment that may be
performed on the EFI system. The standard idle speed
setting for EFI engines is 1500 RPM, but certain
applications might require a different setting. Check
the equipment manufacturer’s recommendation.
Fuel Rail
Throttle Body
Intake Manifold
Low Idle Speed
Adjusting Screw
CAUTION:
Fuel lines between the fuel pump and fuel rail must be made
from SAE 30 R9 fuel line. Standard fuel line (SAE 30 R7)
may
only be used between the fuel tank and pump (5/16”
ID) and for the return line from the pressure regulator to
the tank (1/4” ID). All high-pressure fuel line connections
must be secured with Oetiker Clamps (Kohler Part No.
24 237 05-S), installed/crimped with the corresponding
pliers.
Throttle Body/Intake Manifold Assembly