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1988 Mercury 50hp 2 stroke 3 cylinder outboard

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cleber3

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"I have a 1988 Mercury 50hp 2

"I have a 1988 Mercury 50hp 2 stroke 3 cylinder outboard and a motor that has been sitting for 4 years before using. The motor won't idle, idles rough and then dies. I didn't clean the carbs yet but I have fresh gas and install new fuel line and new fuel filter. I checked for spark in every plug and it was good. Any way I install each new plug. I Tested compression = 110psi in 2 cylinders and the compression is 90psi in the other. Cylinder 1 by the top compression is 110psi and cylinder 2 of the middle also the compression is 110psi, cylinder 3 underneath is little difference 90psi.
The cylinder 3 that could it be the problem makes motor won't idle? I should replace the piston rings?

I noticed white smoke coming out of the exhaust.

By the way with one is cylinder number 1: First on top or first on bottom?
Thanks!"
 
"90psi and a 20psi differnce w

"90psi and a 20psi differnce wont affect idle, but white smoke coming out could be getting some water in there.. with it running and some protected plug wire pliers remove each plug wire, if it doesn't change RPM that cylinder isn't firing."
 
"10-15% difference, changeing

"10-15% difference, changeing the rings would be a good idea, if you do it.. I'd do all 3 and have the cylinders lightly honed..

I cylinder could be not firing either it's not getting fuel or too much, can sometimes clear it by revving the engine a bit and putting your hand over the carb and effectively choking and and making it suck harder through the jets, thereby clearing them out, helps maybe 20-25% of the time, else the bottom carb probably needs cleaning, it's usually the bottom carb thats causing the issue."
 
Without removeing and cleaning

Without removeing and cleaning the carbs there is no way you know for sure if the jets are clean. NO GAS MEANS NO OIL=death of a 2 stroke
 
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