1986-7 Mercury 25xd Won't Run WOT

Austen24

Cadet
Joined
Aug 12, 2018
Messages
6
I have a 1986-7 Mercury 25hp that I have been working on. Had issues with flooding out the carb and found hole in float causing in to sink in the bowl. New float and solved that problem. Take it out and now will bog/decelerate at WOT. It'll run mid throttle fine and run WOT for about 5 seconds then die down. Go back to idle speeds then it will accelerate again with same results. Fuel issue? or Coil issue? Using same fuel line from a different motor and no issues on it. So fuel line/bulb should not be an issue. Any help appreciated to get this thing dialed in. Thanks in advance.
 

flyingscott

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Apr 8, 2014
Messages
7,985
Does pumping the ball make it run better? Did you set the float height correctly? Did you rebuild the carb with a quality kit?
 

Austen24

Cadet
Joined
Aug 12, 2018
Messages
6
When I pumped the bulb it seemed to try to flood it out rather than help. As for rebuilding carb I have not yet replaced gaskets and all. I did clean out all the jets and wipe down. The motor was running fine prior to float issues. Took it to lake and with fuel line hooked up, fuel would pour out of carb. I pulled the bowl to see the float and noticed it full of fuel. Replaced with one from local boat shop and now idles great, runs at low and mid throttle great. Hit full throttle and then die down. Ran by myself and ran WOT about 10 seconds. Added two guys to the boat and wouldn't even reach WOT before dying down. Led me to think a weak coil, but I also am not hugely knowledgeable.
 

flyingscott

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Joined
Apr 8, 2014
Messages
7,985
Do a compression test and spark test. If you had the carb off did you replace the base gasket?
 
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