Fuel Injector Details; Checking Injectors - Kohler CH18-745 Service Manual

Kohler Engine Parts Call K&T 606-678-9623 or 606-561-4983
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.
1
2
3
4
Multi-Orifice
Director Plate with
Calibrated Opening
1. Filter strainer in fuel supply
2. Electrical connection
3. Solenoid winding
4. Valve housing
Figure 5B-18. 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
2. When temperatures prohibit touching, listen for a
5
6
7
Figure 5B-19. Checking Injectors.
3. Disconnect the electrical connector from an
5. Armature
6. Valve body
7. Valve needle
If an injector is not operating, it can indicate either a
bad injector, or a wiring/electrical connection problem.
Check as follows:
NOTE: Do not apply voltage to the fuel injector(s).
1. Disconnect the electrical connector from both
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EFI Fuel System
operational vibration, indicating that they are
opening and closing.
buzzing or clicking sound with a screwdriver or
mechanic's stethoscope (see Figure 5B-19).
injector and listen for a change in idle
performance (only running on one cylinder) or a
change in injector noise or vibration.
Excessive voltage will burn out the injector(s).
Do not ground the injector(s) with the ignition
"on". Injector(s) will open/turn on if relay is
energized.
injectors. Plug the 12 volt test light (SPX Part No.
KO3217-6) in one connector.
Section 5B
Listen Here
5B
5B.15