85 merc inline 6 bogs- no power

floaterdude

Cadet
Joined
Nov 5, 2002
Messages
6
I was pulling my kids on a wakeboard a few weeks ago and the engine worked fine, plenty of power, then we took a break and did some slow cruising for a while, then powered up to get back to the dock and no power - just makes a dogged muffled sound and you couldn't go any faster than about 15 to 20 mph.
Since then I have changed plugs, put temp clear vinyl hoses on tank connections, found one tank to have an air leak on a loose fitting inside tank, fixed it,checked fuel pump filter and diaphram ( new last year) re-adjusted the carbs. Checked linkage on spark advance which was calibrated last year.
Did a compression test - 150 psi on all cylinders. Basically checked all the mechanical stuff. The engine starts and idles fine and will high rev in neutral at the dock or with muffs. Could it be a plugged main jet in one of the carbs? Could it be a ignition pack or coil? Can I test it or should I take it in?
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: 85 merc inline 6 bogs- no power

First make sure you have fire on all 6 cyls, if you do then clean the carbs
 

olemerc115

Cadet
Joined
Jul 6, 2008
Messages
28
Re: 85 merc inline 6 bogs- no power

seems like these old merc inline 6 all do this crap, mine is driving me crazy, has anyone ever fixed this problem, If they all do it there is something that always goes bad on these engines doing this to them, can you hook up the timing light on the spark plug wires as you bog the engine on the lake, if the light does not flash that cyliner isnt firing, like his mine is great until you try to plane off or put the engine under any load situation,
 
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