Fuel Injector Details - Kohler command pro ECH749 Service Manual

EFI SYSTEM-BOSCH

Fuel Injector Details

A
B
C
D
H
A
Filter Strainer In
Fuel Supply
C Solenoid Winding
E Armature
G
Valve Needle
Injector problems typically fall into three general
categories: electrical, dirty/clogged, or leakage. An
electrical problem usually causes one or both of injectors
to stop functioning. Several methods may be used to
check if injectors are operating.
1. With 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.
NOTE: Do not apply voltage to fuel injector(s).
Excessive voltage will burn out injector(s). Do
not ground injector(s) with ignition ON.
Injector(s) will open/turn on if relay is energized.
3. Disconnect 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:
1. Disconnect electrical connector from both injectors.
Plug a 12 volt noid light (part of EFI Service Kit, see
Tools and Aids) into one connector.
68
E
E
G
B
Electrical
Connection
D Valve Housing
F Valve Body
H Multi-Orifi ce Director
Plate With
Calibrated Opening
KohlerEngines.com
2. Make sure all safety switch requirements are met.
Crank engine and check for fl ashing of test light.
Repeat test at other connector.
a. If fl ashing occurs, use an ohmmeter (Rx1 scale)
and check resistance of each injector across two
terminals. Proper resistance is 12-20 Ω. If injector
resistance is correct, check whether connector
and injector terminals are making a good
connection. If resistance is not correct, replace
injector following steps 1-8 and 13-16 below.
b. If no fl ashing occurs, reattach connectors to both
injectors. Disconnect main harness connector
from ECU and connector from relay. Set
ohmmeter to Rx1 scale and check injector circuit
resistance as follows.
"24 Pin" (MSE 1.0) Plastic-Cased ECU:
Check resistance between relay terminal #87
and pin #16 in main connector. Then check
resistance between relay terminal
#87 and pin #17. Resistance should be 4-15
Ω for each circuit. "32 Pin" (MSE 1.1)
Plastic-Cased ECU: Check resistance
between relay terminal #87 and pin #14 in
main connector. Then check resistance
between relay terminal #87 and pin #15.
Resistance should be 4-15 Ω for each circuit.
Check all electrical connections, connectors, and wiring
harness leads if resistance is incorrect.
Injector leakage is very unlikely, but in those rare
instances it can be internal (past tip of valve needle), or
external (weeping around injector body). Loss of system
pressure from leakage can cause hot restart problems
and longer cranking times. To check for leakage it will
be necessary to loosen or remove blower housing which
may involve removing engine from unit.
24 690 01 Rev. K