my 115 hp 2006 with 190 hours is running fine up to 4000 rpm. shows 15.1 V on fish finder and 15 on dash gauge (has showed 15.1 from the very first time out). above 4000 rpm the voltage shows 16.3 and the dash gauge dances between 15 and max. the alarm comes on with a 1 beep sequence. other than...