Yamaha YZF-R125 Service Manual: Checking the fuel sender

1. Drain the fuel from the fuel tank.

2. Check:

Fuel sender resistance Out of specification → Replace the fuel sender.


a. Connect the pocket tester ( ×
10) to the fuel sender coupler as shown.


  • Positive tester probe
    sky blue "1"
  • Negative tester probe
    orange/white "2"

Checking the fuel sender


A. Full fuel tank position

B. Empty fuel tank position

b. Measure the fuel sender resistance.

    Checking the horn
    1. Check: Horn resistance Out of specification Replace. a. Disconnect the horn connectors from the horn terminals. b. Connect the pocket tester ( × 1) to the horn terminals. Positiv ...

    Checking the speed sensor
    1. Check: Speed sensor output voltage Out of specification → Replace. a. Connect the pocket tester (DC 20 V) to the speed sensor coupler (wire harness end) as shown. Positive tester pro ...

    Other materials:

    Circuit diagram
    2. Crankshaft position sensor 4. Main fuse 5. Main switch 6. Radiator fan motor fuse 8. Sidestand switch 9. Battery 17.Engine stop switch 19.Intake air pressure sensor 20.Intake air temperature sensor 21.Throttle position sensor 22.Coolant temperature sensor 23.Lean angle sensor 24.S ...

    Clutch lever
    Clutch lever Clutch lever The clutch lever is located at the left handlebar grip. To disengage the clutch, pull the lever toward the handlebar grip. To engage the clutch, release the lever. The lever should be pulled rapidly and released slowly for smooth clutch operation. Th ...

    Checking the rectifier/regulator
    1. Check: Rectifier/regulator output voltage Out of specification → Replace the rectifier/ regulator. a. Set the engine tachometer to the spark plug lead. b. Connect the pocket tester (DC 20 V) to the rectifier/regulator coupler as shown. Positive tester probe red "1" Negat ...

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