Kohler COMMAND CV17-745 Service Manual page 68

Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
Section 5B
EFI Fuel System
Figure 5B-15. Style 2 Fuel Injector.
General
The fuel injectors mount into the throttle body/intake
manifold, and the fuel rail attaches to them at the top
end. Replaceable O-Rings on both ends of the injector
prevent external fuel leakage and also insulate it from
heat and vibration. A special clip connects each
injector to the fuel rail and holds it in place. The
O-Rings should be replaced anytime the injector is
removed.
When the key switch is on and the relay is closed, the
fuel rail is pressurized, and voltage is present at the
injector. At the proper instant, the ECU completes the
ground circuit, energizing the injector. The valve needle
in the injector is opened electromagnetically, and the
pressure in the fuel rail forces fuel down through the
inside. The "director plate" at the tip of the injector (see
inset) contains a series of calibrated openings which
directs the fuel into the manifold in a cone-shaped
spray pattern.
5B.14
Multi-Orifice
Director Plate With
Calibrated Opening
1. Filter strainer in
fuel supply
2. Electrical connection
3. Solenoid winding
Figure 5B-16. Fuel Injector Details.
The injector is opened and closed once for each
crankshaft revolution, however only one-half the total
amount of fuel needed for one firing is injected during
each opening. The amount of fuel injected is controlled
by the ECU and determined by the length of time the
valve needle is held open, also referred to as the
"injection duration" or "pulse width". It may vary in
length from 1.5-8 milliseconds depending on the speed
and load requirements of the engine.
Service
Injector problems typically fall into three general
categories: electrical, dirty/clogged, or leakage. An
electrical problem usually causes one or both of the
injectors to stop functioning. Several methods may be
used to check if the injectors are operating.
1. With the engine running at idle, feel for
operational vibration, indicating that they are
opening and closing.
2. When temperatures prohibit touching, listen for a
buzzing or clicking sound with a screwdriver or
mechanic's stethoscope (see Figure 5B-17).
www.mymowerparts.com
1
2
3
5
4
6
7
4. Valve housing
5. Armature
6. Valve body
7. Valve needle