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 ...

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    Engine 1. Cylinder and cylinder head Incorrect valve clearance Damaged valve train components 2. Air filter Clogged air filter element Fuel system 1. Throttle body Damaged or loose throttle body joint Improperly adjusted engine idling speed (idle adjusting screw) Improper ...

    Separating the crankcase
    1. Remove: Crankcase bolts NOTE: Loosen each bolt 1/4 of a turn at a time, in stages and in the proper sequence as shown. A. Right crankcase B. Left crankcase 2. Turn: Shift drum segment NOTE: Turn the shift drum segment "1" to the position shown in the illustration. In this ...

    Checking the front fork legs
    The following procedure applies to both of the front fork legs. 1. Check: Inner tube Outer tube Bends/damage/scratches Replace. WARNINGDo not attempt to straighten a bent inner tube as this may dangerously weaken it. 2. Measure: Spring free length "a" Out of sp ...

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