2005 YAMAHA VX110 Service Manual

7-14
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IGNITION SPARK
WARNING
When checking the spark gap, do not
touch any of the connections of the spark
checker/ignition tester lead wires.
When performing the spark gap test, take
special care not to let sparks leak out of
the removed spark plug cap.
When performing the spark gap check,
keep flammable gas or liquids away,
since this test can produce sparks.
1. Check:
Ignition spark
Weak →
Check the ECM output peak
voltage.
Check the ignition coil for resistance.
Checking steps:
Connect the spark plug cap to the special
service tool.
Spark checker:
YM-34487
Ignition tester:
90890-06754
Crank the engine and observe the igni-
tion system spark through the discharge
window.
OK
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7-15
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IGNITION SYSTEM PEAK VOLTAGE
WARNING
When checking the electrical components,
do not touch any of the connections of the
digital tester lead wires.
NOTE:
If there is no spark, or the spark is weak,
continue with the ignition system test.
If a good spark is obtained, the problem is
not with the ignition system, but possibly with
the spark plug(s) or another component.
1. Measure:
ECM output peak voltage
Below specification →
Measure the
pickup coil output peak voltage.
NOTE:
When measuring the ECM output peak volt-
age while cranking the engine, disconnect
the ignition coil couplers for all cylinders
except for the cylinder being measured.
To crank the engine, connect the engine
shut-off cord (lanyard) to the engine shut-off
switch, and then press the start switch.
Test harness (2 pins):
New: YB-06867
Current: YB-06767
Test harness FWY-2 (2 pins):
New: 90890-06867
Current: 90890-06767
ECM output peak voltage:
Black/red (B/R) –
Red/yellow (R/Y)
Black/white (B/W) –
Red/yellow (R/Y)
Black/yellow (B/Y) –
Red/yellow (R/Y)
Black/green (B/G) –
Red/yellow (R/Y)
r/minLoaded
Cranking 2,000 3,500
V 90 130 140
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7-16
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2. Measure:
Pickup coil output peak voltage
Below specification →
Replace the
pickup coil.
Above specification →
Replace the
ECM.
NOTE:
To crank the engine, connect the engine shut-
off cord (lanyard) to the engine shut-off switch,
and then press the start switch and engine
stop switch simultaneously.
Test harness (3 pins):
New: YB-06877
Current: YB-06777
Test harness HM090-3 (3 pins):
New: 90890-06877
Current: 90890-06777
Pickup coil output peak voltage:
White/black (W/B) –
Black/orange (B/O)
r/minUnloaded Loaded
Cranking 2,000 3,500
V 8.0 6.9 19.4 25.1
3. Measure:
Lighting coil output peak voltage
Below specification →
Replace the light-
ing coil.
Test harness (3 pins):
New: YB-06870
Current: YB-06770
Test harness SMT250-3 (3 pins):
New: 90890-06870
Current: 90890-06770
Lighting coil output peak voltage:
Green (G) – Green (G)
r/minUnloaded
Cranking 2,000 3,500
V 7.8 24.5 41.6
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NOTE:
To crank the engine, connect the engine shut-
off cord (lanyard) to the engine shut-off switch,
and then press the start switch and engine
stop switch simultaneously.
4. Measure:
Rectifier/regulator output voltage
Below specification →
Replace the recti-
fier/regulator.
NOTE:
Do not use the peak voltage adapter to mea-
sure the output voltage.
Disconnect the output lead of the tester har-
ness.
Test harness (6 pins):
YB-06848
Test harness FSW-6A (6 pins):
90890-06848
Rectifier/regulator output
voltage:
Red (R) – Black (B)
r/minUnloaded
3,500
V 13.0
BATTERY
Refer to “ELECTRICAL” in Chapter 3.
FUSE
Refer to “STARTING SYSTEM”.
SPARK PLUGS
Refer to “POWER UNIT” in Chapter 3.
IGNITION SYSTEM
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7-18
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–+ELEC
IGNITION COIL
1. Measure:
Primary coil resistance
Out of specification →
Replace.
NOTE:
When measuring a resistance of 10 Ω
or less
using a digital tester, the correct measurement
cannot be obtained because of the tester’s
internal resistance.
Refer to “Low resistance measurement”.
Primary coil resistance:
1.19–1.61
Ω at 20 °C (68 °F)
2. Measure:
Secondary coil resistance
Out of specification →
Replace.
Secondary coil resistance:
8.5–11.5 k
Ω at 20 °C (68 °F)
ENGINE STOP SWITCH
1. Check:
Engine stop switch continuity
Out of specification →
Replace.
Engine stop switch continuity
(black coupler)
Clip PositionLead color
White Black
InstalledFree
Push
RemovedFree
Push
IGNITION SYSTEM
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7-19
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ENGINE TEMPERATURE SENSOR
1. Measure:
Engine temperature sensor resistance
(at the specified temperature)
Out of specification →
Replace.
Engine temperature sensor
resistance:
20 °C (68 °F): 54.2–69.0 k
Ω
100 °C (212 °F): 3.12–3.48 k
Ω
Measurement steps:
Suspend the engine temperature sensor
in a container filled with water.
Place a thermometer in the water.
Slowly heat the water.
Measure the resistance when the speci-
fied temperature is reached.
SENSOR ASSEMBLY
1. Check:
Intake air temperature sensor
Out of specification →
Replace the sen-
sor assembly.
Checking steps:
Measure the ambient temperature.
Connect a computer to the watercraft and
use the Yamaha Diagnostic System to
display the intake air temperature.
If the ambient temperature and the dis-
played intake air temperature differ by
more than ±
5 °C (±
9 °F), replace the
sensor assembly.
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7-20
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THERMOSWITCH (ENGINE)
1. Check:
Thermoswitch (engine) continuity
(at the specified temperature)
Out of specification →
Replace.
1 No continuity
È Temperature
2 Continuity
É Time
NOTE:
The thermoswitch (engine) connector is blue.
Thermoswitch (engine) continuity
temperature:
a 84–90 °C (183–194 °F)
b 70–84 °C (158–183 °F)
Checking steps:
Suspend the thermoswitch (engine) in a
container filled with water.
Place a thermometer in the water.
Slowly heat the water.
Measure the continuity when the speci-
fied temperature is reached.
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THERMOSWITCH (EXHAUST)
1. Check:
Thermoswitch (exhaust) continuity
(at the specified temperature)
Out of specification →
Replace.
1 No continuity
È Temperature
2 Continuity
É Time
NOTE:
The thermoswitch (exhaust) connector is
black.
Thermoswitch (exhaust)
continuity temperature:
a 80–86 °C (176–187 °F)
b 66–80 °C (151–176 °F)
Checking steps:
Suspend the thermoswitch (exhaust) in a
container filled with water.
Place a thermometer in the water.
Slowly heat the water.
Measure the continuity when the speci-
fied temperature is reached.
IGNITION SYSTEM
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