2008 Etch 115hp Evinrude

by Rammona Schatten
(Ont Canada)

When we first start the motor ir revs up and goes fast then after a few minutes it goes down to a trolling speed and will not go fast. We hold the throttle flat out and it still only crawls along....any ideas ehat the problem could be. It is a very clean pristine motor. The exhaust valve will not stay open, we purchased a kit to keep it open but it still only crawls?