1983 ish mercury 90hp engine tech help

Gamblerman

Petty Officer 3rd Class
Joined
Jan 18, 2008
Messages
75
,ok guys this is what i have going on last year she ran great but started to have problem at the end of the season.
Cold start real pain but i know they where from the get go but when warm she started with no problem ok so this was my problem last year try to get up on plane she would die and stall out like i was not getting fuel so i did a complet tune up
plugs, wires,carbs rebuild ,fuel pump rebuilt ,new water sep,timing, but that did nothing for my problem now when you would at some point get her moving and open her up wot she would run great no problem but on the lower end she was running poor. Ok so now i take her out for the first time this year to see what its going to do.Well it runs great all day (I just dont get it ) ok two day later Im out on the lake I make a fast run to my fishing hot spot all is good . I get ready to make my next run and she start to do the same thing as last year but this time at wot she has a miss and running poor.So i get the boat home and I start to pull the plug one at a time. I get to the last two bottom plugs and they are clean but with small water droplets ok so now i do a compression test and this is what i come up with from top to bottom I get 95,97,100,95,95,100 I did this test three times and came up with the same numbers.

Now what should I do next and how do i fix this problem,
This motor has alway been taken care of by the mercury dealer every year when my dad had it on his boat new from the same dealer and he has never had problem with it never over heated alway put away in a heated building
Now Im not new to outboards and I have had many boats over the years but never this kind of problem with water.
Also I replaced the the fuel every year and water fuel sep also so i know its not water in my fuel

If someone can tell me hat i should do next that would be great

Thanks shawn
 

Gamblerman

Petty Officer 3rd Class
Joined
Jan 18, 2008
Messages
75
Re: 1983 ish mercury 90hp engine tech help

,ok guys this is what i have going on last year she ran great but started to have problem at the end of the season.
Cold start real pain but i know they where from the get go but when warm she started with no problem ok so this was my problem last year try to get up on plane she would die and stall out like i was not getting fuel so i did a complet tune up
plugs, wires,carbs rebuild ,fuel pump rebuilt ,new water sep,timing, but that did nothing for my problem now when you would at some point get her moving and open her up wot she would run great no problem but on the lower end she was running poor. Ok so now i take her out for the first time this year to see what its going to do.Well it runs great all day (I just dont get it ) ok two day later Im out on the lake I make a fast run to my fishing hot spot all is good . I get ready to make my next run and she start to do the same thing as last year but this time at wot she has a miss and running poor.So i get the boat home and I start to pull the plug one at a time. I get to the last two bottom plugs and they are clean but with small water droplets ok so now i do a compression test and this is what i come up with from top to bottom I get 95,97,100,95,95,100 I did this test three times and came up with the same numbers.

Now what should I do next and how do i fix this problem,
This motor has alway been taken care of by the mercury dealer every year when my dad had it on his boat new from the same dealer and he has never had problem with it never over heated alway put away in a heated building
Now Im not new to outboards and I have had many boats over the years but never this kind of problem with water.
Also I replaced the the fuel every year and water fuel sep also so i know its not water in my fuel

If someone can tell me hat i should do next that would be great

Thanks shawn

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