jshirlA couple of things come to mind. Do you have smartcraft guages? If you have a new power head are you still in break-in mode. I dont know what year or model Optimax ,but the break in period is as follows:( from merc 3.0 litre board @ BBC.com)ALWAYS READ THE INSTRUCTIONS IN YOUR OWNERS MANUAL AND FOLLOW THEM!Proper engine break-in is critically important to the performance, life and longevity of your engine.In addition to (and in combination with) the manual recommendations, I would make the following recommendations:-Quickleen should be utilized in EVERY tank of fuel…. from the FIRST TANK- to the LAST.-Start engine and allow it to warm up to operating temperature. I strongly recommend the use of a Smartcraft Instrument, which will allow you to monitor and ensure that the engine reaches a MINIMUM of 120 degrees before accelerating above 1200 RPMs.-During the first 3 hours of break-in, keep your engine trim “no higher” than “level trim”. If youre running a hydraulic jackplate, keep the jackplate down as far as “safely” possible. This will help to load the engine, and promotes proper break-in.-Make your first acceleration of the day GRADUALLY. Your target RPM for Breakin (per manual) is 4500-5500 RPM (approximately 3/4 throttle). In all honesty, RPMs between 4000-5000 RPMs are very suitable for break-in. Vary engine RPMs at least once every 2 minutes.-During the first 3 hours of break-in, it is wise to plan a complete shut-down of the engine, while allowing the engine to completely cool down. This can be accomplished while you fish, or- if you prefer, by continuing your break-in on another outing. This “cooldown” is often referred to as a “HEAT CYCLE”. I personally recommend a MINIMUM of ONE heat cycle during the first three hours of operation.-It is ALWAYS wise to allow the engine to idle for approximately 60 seconds before shutdown. This allows engine temperature to stabilize within its “thermostatic control” temperature range, and can help to extend your engines life.-After three hours of operation, FULL THROTTLE and additional trim may be used for SHORT RUNS (recommend five minutes or less).-Continue to vary engine RPMs at least once every 5 minutes over the first 10 HOURS of operation.-Once 10 hours have been reached, begin “NORMAL” operation.Possibly 1)you are trying to push a new powerhead before fully broken in 2) analog tach is not reading correctly 3) plug or plugs are fouled after double oiling period Quickest way to figure it out is a trip to Merc dealer and have the run history downloaded or try asking Don on the Merc 3 litre board at http://www.bassboatcentral.com and have the model and serial number at hand to post in your question. good luckBobLast edited by Bobcat on April 7th, 2012, 5:56 pm, edited 1 time in total.
