1971 Johnson 125HP outboards Service Manual, Page 40Get this manual
TESTING SENSOR CIRCUIT
aConnect ohmmeter leads to sensor wire plugA 4-6 ohm reading indicates sensor circuit is "OK While meter is connected, work wire back and forth for indication of loose connectionsbConnect one meter lead to groundClose and open throttle to shift anti-reverse spring from groundMeter should read at least 100,000 ohmsWhile meter is connected, work wires entering the distributor base back and forth for indication of groundscIf sensor ohms checks "OK remove flywheel and check sensor .028 air gapTighten sensor and base plate connections securelyInspect distributor cap, rotor, and high tension leads for cracks, carbon trails, and corrosionNOTE: cracked or leaking distributor cap andor rotor, leaking high tension leads, may prevent spark from reaching spark plugsCheck carefully
TESTING COIL (SENSOR CmCUIT AND PULSE PACK "OK")