I have a Yanmar 3GM30 with 425 hours. It was on the boat when I acquired it 3.5 years ago. The engine runs very well and I have no complaints except that it is generally difficult to start when cold. I have tried moving the throttle all the way from barely open to wide open and nothing seems to help. I mentioned this to the local Yanmar dealer at a recent boat show and he said that maybe the battery was not providing sufficient power to turn over the engine fast enough. I just installed a brand new group 27 starting battery and this has not made any difference. Once the engine gets going it can easily be started again. I do not have any kind of electric fuel pump. Any ideas as to what is happening?