I've got a 2003 Mercury 90 HP 4-stroke that makes a very noticeable pulsating humming noise in neutral at idle (about 850 RPM). The sound is louder after running it hard for 5+ minutes. If I put it into forward (or reverse), still at idle speed, the sound goes away. There are 30 hours on the motor. It's made the sound since it was new. I didn't think much of it until a buddy was on board for the first time and asked what the noise was. Is this pulsating humming sound in neutral normal?<br /><br />Thanks,<br />Bill
