Yamaha F150B Service Manual

Also see for F150B: Owner's manual Service manual Owner's manual

4-14Troubleshooting the power unit012345678910ASymptom 1: Unstable engine idle speed, poor acceleration, poor performance, or limited engine speed.Symptom 2 Cause 1 Cause 2 Checking step Refer topage—Throttle valves does not synchronize — Synchronize the throttle valves. 6-23Throttle link malfunction — Check the throttle link for clack or worn. 6-18Throttle link and throttle cable are notinstalled correctly — Adjust the throttle link and throttle cable. 10-16Spark plug does notspark (some cylinders)Spark plug malfunction — Check the ignition spark. 5-28Check the spark plugs. 10-15Short, open, or loose connection in ignitioncoil circuit—Check the spark plug wires resistance. 5-28Check the ignition coil input voltage. 5-29A-5Check the ignition coil output peak voltage. 5-29Check 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-5Ignition coil malfunction — Check the ignition coil resistance. 5-29Engine ECM malfunction — Replace the engine ECM. 7-15High-pressure fuel linemalfunction (fuel pres-sure is low)Pressure regulator malfunction — Check the pressure regulator. 6-5High-pressure fuel pump malfunction — Check the fuel pressure. 6-4Fuel not supplied (somecylinders)Fuel injector malfunction—Check the fuel injector operation using theYDIS.5-24Check the fuel injector resistance. 5-24Short, open, or loose connection in fuelinjector circuit—Check the fuel injector input voltage. 5-24A-3Check for wiring continuity between the fuelinjector and main relay.5-24A-3Check for wiring continuity between the fuelinjector and engine ECM.5-24A-3Clogged fuel injector filter — Replace the fuel injector. 6-26Engine ECM malfunction — Replace the engine ECM. 7-15