Merc 800 speed died off

[brooksk]

Folks,<br />I have an 18'Starcraft V-hull w/ '78 Mercury 800 80hp and while finishing up an hour of tube pulling I noticed the boats speed would not climb over 20mph at WOT when an hour earlier I had it up to 32mph. I did not notice any shaking or roughness to the motor, and when back at dock w/motor trimmed up did not see anything wrapped aroung the prop. Does this sound like one or more cylinders not firing or one loaded up with overrich fuel/oil? Could it be bad coils or power pack? What the first thing you'd recommend?<br />All comments appreciated.

 

[12Footer]

Re: Merc 800 speed died off

How well does she idle in gear?<br />If it does at all, I would check the hull for soggy floatation. You might even see this as a strange "squat" in the bow, or a tilt to one side. Also, check for a plugged drain hole in one or more srtringers under the deck.<br />This would also be noticeable as an odd stance in the water, or an audible "sloshing", when the bow is raised quickly on the trailer (it will also wiegh a great deal more.