Yamaha YFM250RX 2008 Service Manual page 302

EBS01083
3. The carburetor heater fails to come on.
1. Thermo switch
• Disconnect the thermo switch from the wire-
harness.
• Connect the pocket tester (Ω × 1) to the
thermo switch lead.
Tester positive probe → black
Tester negative probe → black
• Check the thermo switch for continuity at
the temperatures indicated below.
ON
11°C±3°C
(51.8°F±5.4°F)
COOL DOWN
HEAT UP
• Does the thermo switch operated properly?
YES
OFF
16°C±3°C
(60.8°F±5.4°F)
NO
Replace the thermo
switch.
7-35
SIGNAL SYSTEM
2. Carburetor warmer
• Remove the carburetor heating element
from the carburetor.
• Connect the pocket tester (Ω × 1) to the car-
buretor heating element.
Tester positive probe →
heating element
Tester negative probe →
heating element body
• Measure the carburetor heating element
resistance.
Carburetor heating element resis-
tance:
6 ~ 12 Ω (20°C)
• Is the carburetor heating element OK?
YES
This circuit is OK.
ELEC
1
2
NO
Replace the carbu-
retor warmer ele-
ment.