1979 Mercury 80HP

NMCatsFan

Recruit
Joined
Aug 5, 2015
Messages
1
I have a strange problem. Engine starts easy, idles good. The boat will cruise at about 10mph all day which I figure is about 20% of power regardless of throttle position unless I go full power, then it will bog and try to die. Sometimes if you quickly go from quarter throttle to full power and then pull it back about an inch (of throttle travel) it will do a normal hole shot and run great making full power. Until I make a turn and then it will bog down again. Any ideas? So here is the scenario again:
1. Start engine, starts nice every time.
2. Start cruising at anywhere from quarter throttle to approx 3/4 throttle, doesn't matter. Boat will go about 10mph.
3. Move throttle very quickly from 1/4 throttle to full throttle and back off about an inch, good hole shot, start moving at approx 25mph to 30mph. Once I go into a turn and the engine will bog down again and sometimes stall. Always starts back up pretty easily. Usually after 3 or 4 hours of cruising this trick stops working though.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,571
If the carbs are clean, they may be misadjusted. Richn them 1/8 turn at a time and test acceleration after each adjustment. If carbs are not clean, they need to be rebuilt.
 
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