Checking The Rectifier/Regulator; Checking The Fuel Sender; Checking The Resistor - Yamaha YZ450FX 2019 Owner's Service Manual

b. Measure the stator coil resistance.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAM30301

CHECKING THE RECTIFIER/REGULATOR

1. Check:
• Rectifier/regulator output voltage
Out of specification  Replace.
Regulated voltage (DC)
14.0–14.8 V
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Set the digital tachometer to the ignition coil.
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
b. Connect the digital circuit tester (DCV) to the
rectifier/regulator coupler.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
• Positive tester probe 
Red "1"
• Negative tester probe 
Black "2"
W W
1 2
B R
2 1
8-65
ELECTRICAL COMPONENTS
c. Start the engine and let it run at about 5000
r/min.
d. Measure the output voltage.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAM30359

CHECKING THE FUEL SENDER

1. Disconnect:
• Starter motor lead
(from the starter relay)
2. Connect:
• Fuel pump coupler
3. Push the start switch.
4. Check:
• Fuel level warning light
Out of specification  Replace the fuel
pump.
Fuel pump is atmosphere "A"
 Fuel level warning light is come on
Fuel pump is soaked in fuel "B"
 Fuel level warning light is goes off
EAM30360

CHECKING THE RESISTOR

1. Disconnect:
• Resistor coupler
(from the wire harness)
2. Check:
• Resistor resistance
Out of specification  Replace the resistor.
Resistor resistance
64.6–71.4 
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the digital circuit tester () to the re-
sistor as shown.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927