Merc 90 FourStroke carburetor rebuild

[pcrussell50]

solved: turned out the rings were all carboned up. It's been great now ever since



My fishboat has a 2000, carbureted Merc 90hp FourStroke.

6 months ago, it started: -hanging at mid-power, not wanting to transition to the WOT fuel circuit without coaxing and easing it up there.


This was no biggie to me because it ran great in every other phase, and the pacific ocean is usually too rough to go full speed in the little, flat dead rise 17' Whaler.


But now:
-it would barely idle anymore because of a bad misfire


Sooo--yesterday I yanked all four of the carbs, one for each cylinder, and disassembled them. They looked spotlessly clean except for one thing--carb#3--from the top. The little rubber-tipped needle connected to the float, was stuck in it's bore, with hard crud all over it. I forget, but I think it was jammed shut.


the carb bodies with all the little bits are in the sonic cleaner soaking and vibrating in kerosene.


observations:
I guess the #3 cylinder was misfiring because the float bowl couldn't fill properly.


seems weird to me that every other part of the carbs looked sooo clean except that one float needle.


every tank had sta-bil and quickkleen in it.


the gunk on the needle was hard and mostly white--not the typical color of varnish fuel or chunks of sta-bil.


man these EPA carbs have some tiiiny passages in them.


I'm diggin' the o-ring-style assembly over the old skool paper gaskets on my carb'ed crossflows .


I have been religious about starting it on the muffs every week, but it sat for nearly a year by the PO without running, (but with sta-bil and quickleen).