Yamaha F150B Service Manual

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4-12Troubleshooting the power unit012345678910ASymptom 1: Engine will not start (engine cranks).Symptom 2 Cause 1 Cause 2 Checking step Refer topageDischarged battery Battery performance decrement — Check the battery capacity and specificgravity.10-4Stator assembly malfunction—Measure the lighting coil output peak volt-age.5-26Measure the lighting coil resistance. 5-26Short, open, or loose connection in chargingcircuit —Check the battery cable and terminals forproper connection. —Check the charging circuit wiring connectionand damage.A-7Engine ECM does notoperateMain relay malfunction — Check the main relay. 5-14A-5Blown fuse — Check the fuse. 5-2A-5Short, open, or loose connection in engineECM circuit —Check for wiring continuity between themain relay and engine ECM.5-15A-5Check for wiring continuity between theengine ECM and ground.5-15A-5Engine ECM malfunction — Replace the engine ECM. 7-15Spark plug does notspark (all cylinders)Pulser coil malfunction — Check the pulser coil resistance. 5-30Short, open, or loose connection in pulsercoil circuit — Check for wiring continuity between thepulser coil and engine ECM.5-30A-5Short, open, or loose connection in ignitioncoil circuit—Check the ignition coil input voltage. 5-29A-5Check for wiring continuity between the igni-tion coil and engine ECM.5-29A-5Check for wiring continuity between the igni-tion coil and main relay.5-29A-5