Kohler LH630-775 Service Manual page 53

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Multi-Orifice
Director Plate With
Calibrated Opening
1. Filter strainer in
fuel supply
2. Electrical connection
3. Solenoid winding
Figure 5B-14. 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-15).
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4. Valve housing
5. Armature
6. Valve body
7. Valve needle
Figure 5B-15. Checking Injectors.
3. Disconnect the electrical connector from an
injector and listen for a change in idle
performance (only running on one cylinder) or a
change in injector noise or vibration.
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).
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 the relay is energized.
1. Disconnect the electrical connector from both
injectors. Plug a 12 volt noid light (part of EFI
Service Kit, see Section 2) in one connector.
Figure 5B-16. Volt Noid Light.
Section 5B
EFI Fuel System
Listen Here
5B.13
5B