I have a Doral Prestancia 270 with twin 4.3 liter Mercruisers. Recently a
strange problem has developed that I do not understand. When planning at
3400 RPM and the synchronizer at zero now and again the synchronizer will
show the port engine down by 200 to 300 RPM. This lasts from 10 seconds to
30 seconds. When this happens there is a change in the sound of the motors
and when it recovers there is a definite surge in power. The strange thing
is all during these events the two engine tachometers ramain steady at 3400
RPM. I have checked for weeds and do not see anything amiss when doing an
underwater visual check.

If anyone can shed some light on this problem I would be most grateful,

Don

Reel Life
Lake Simcoe, Ontario