Troubleshooting - Yamaha WR125R 2009 Service Manual

EAS27120

TROUBLESHOOTING

The ignition system fails to operate (no spark or intermittent spark).
TIP
• Before troubleshooting, remove the following part(s):
1. Battery cover
2. Rear fender
3. Fuel tank
1. Check the fuses.
(Main and ignition)
Refer to "CHECKING THE FUS-
ES" on page 8-65.
OK ↓
2. Check the battery.
Refer to "CHECKING AND
CHARGING THE BATTERY" on
page 8-65.
OK ↓
3. Check the spark plug.
Refer to "CHECKING THE SPARK
PLUG" on page 3-7.
OK ↓
4. Check the ignition spark gap.
Refer to "CHECKING THE IGNI-
TION SPARK GAP" on page 8-70.
NG ↓
5. Check the spark plug cap.
Refer to "CHECKING THE SPARK
PLUG CAP" on page 8-69.
OK ↓
6. Check the ignition coil.
Refer to "CHECKING THE IGNI-
TION COIL" on page 8-70.
OK ↓
7. Check the crankshaft position sen-
sor.
Refer to "CHECKING THE CRANK-
SHAFT POSITION SENSOR" on
page 8-71.
OK ↓
8. Check the main switch.
Refer to "CHECKING THE
SWITCHES" on page 8-61.
OK ↓
NG →
Replace the fuse(s).
NG →
• Refill battery fluid.
• Clean the battery terminals.
• Recharge or replace the battery.
NG →
Re-gap or replace the spark plug.
OK →
Ignition system is OK.
NG →
Replace the spark plug cap.
NG →
Replace the ignition coil.
NG →
Replace the crankshaft position sen-
sor/stator assembly.
NG →
Replace the main switch.
8-3
IGNITION SYSTEM