TROUBLESHOOTINGBefore performing any troubleshootingprocedures within this section, review theSafety section on page 3.If a problem occurs, stop the engineimmediately. Refer to the SYMPTOMcolumn in the Troubleshooting Chart toidentify the problem.TROUBLESHOOTINGAFTER STARTINGJust after the engine has started, check thefollowing items at a low engine speed:Is sufficient water being dischargedfrom the seawater outlet pipe?If the discharge is low, stop the engineimmediately. Identify the cause and repair.Is the exhaust color normal?The continuous emission of black exhaustsmoke indicates engine overloading. Thisshortens the engine’s life and should beavoided.When operating the engine at low speed forlong periods of time, race the engine onceevery two hours. Race the engine with theclutch in NEUTRAL, accelerate from the lowspeed position to the high speed positionand repeat this process about five times.This is done to clean out carbon from thecylinders and the fuel injection valves.NOTICE: Neglecting to race the enginewill result in poor exhaust color andreduce engine performance.Periodically operate the engine nearmaximum speed while under way. This willgenerate higher exhaust temperatures,which will help clean out hard carbondeposits, maintain engine performance andprolong the life of the engine.GM Series Operation Manual 59© 2007 Yanmar Marine International