Mid 90's 15 hp mercury made force is trying to introduce me to davy jones!

Murky115

Petty Officer 3rd Class
Joined
May 10, 2016
Messages
95
Hello all . I am having some trouble with my mid 90s 15 hp force made by mercury it is mounted on a 14 foot 76 game Fisher with a cathedral hull. . I left the launch ramp she only would run until half throttle then it would die. Undeterred I continued to my destination an island in the Hudson river that is boat in only state camp grounds . I camped messed with the boat a little adjusting the screw in the front of the carb in an attempt to remedy the problem no real luck there.
When it was time for me to return to the real world it was VERY windy I needed to go north up stream. The tide was ebbing and the very strong wind was from the south creating some very big waves . Upon leaving I found the motor would now only run at about an 8th throttle this created a horrible voyage with me just barely going faster then the current and outgoing tide and not faster then the waves at my stern. Is this carburetor. ( just had it off and cleaned needle valve and bowl)? Ignition ( replaced one ignition coil about a year ago and have newer plugs ) ? Fuel lines (they are about two years old )? Just did a cold compression test 98 pounds each cylinder. Also it seemed too hot to me on the way out when it would run at half throttle on the way out . Could my hand on the block no longer then a two count but plenty of water was coming out of the telltale .
 

Murky115

Petty Officer 3rd Class
Joined
May 10, 2016
Messages
95
The Mood is her name
 

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oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
Replace the impeller (river sand destroys them). Measure spark on all leads with an open air, adjustable tester (not the inline type). Look for about a half inch spark to determine the magneto is ready for prime time Tester looks like this, and should run about $10 US at an auto parts store: xLIS50850_1200Wx1200H.jpg.pagespeed.ic.DpYWD8n9Ep.jpg
 

Murky115

Petty Officer 3rd Class
Joined
May 10, 2016
Messages
95
I know I know I'm resurrecting a dinosaur of a thread but it occurred to me that I never finished it. For the good of the forums it must be finished. The problem I was having was air leaking in between the carb and the block . Diagnosed by spraying carb cleaner on that area while the engine was running which bogged her down . Stripped carb mounting bolt allowed leak .
 
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