90hp merc rough idle

[amoler821]

hi everyone. i ve got a 1999 3cyl 90hp 2 stoke. i've been out a couple times this year and it seems to have a rough low idle. it never dies out, just shakes around when running in neutral. when i put it in gear and increase rpms it smooths out. i'm getting the same speed at the same rpm out of it as last year. this weekend i was out drifting a large area of no wake zone. i was in gear just over idle when it was time to make another drift, then shut off while drifting. at the end of the day after another drift, it wouldnt start. i tried everything and eventually flooded it and got towed in. when i got home, it put the muffs on it and it fired right up. i replaced the fuel/water separator, the inline filter under the cowl, replaced the spark plugs and pulled the carbs. the fuel/water separator had some debris in it, but everything else looked brand new. the carbs looked like they were right out of the package. no water or varnish. put everything back together and it starts and idles, just bounces around a bit and sounds like its spitting and sputtering a bit, but it wont die out. and it fires right back up after what seems like half a second.
any ideas would be much appreciated.

 

[Texasmark]

My 2002 had deteriorated internal rubber hoses at 10 years. Found tiny black pieces of rubber in the carb in the low speed section and in the area of the high speed jet....compressed air after cleaning found the jet culprit, low speed section was obvious. I always ran Sea Foam in my fuel to keep things clean and neat internally. Mine was cranky to start first thing of the day then lit right off with the control at idle the rest of the day if it didn't sit longer than 15-20 minutes. Longer than that it needed fast idle up and if no help, seldom, a nudge of fuel enrichment.

Course I ran like a month or so between outings. No doubt starting initially for the day would be a seamless process had I used it regularly.

 

[amoler821]

thanks for the reply. its never been a hard start before. after changing the filters and the cleaning the carbs it was a hard start and only got it started by bumping u the idle control. when it did start the bucket of water had a layer of dirty oil in it. the rest of the afternoon about every hour or so i'd try to start it and it would start right up i came home today, filled a fresh bucket and again a hard start....maybe i screwed up something in the carbs? thing thing would fire right up after a long winter with no problems before.

 

[amoler821]

update--so when i tried to start it tonight, it was still in the down postion in the tub from running it yesterday...it was hard as heck to start, it stumbed then would die...smoke like crazy and filled the tub with black oil....now...i just went back, tilted the motor up to get the tub out from under to and drain it, put the tub under it, tilt the motor back down and refill the tub. crank it for the heck of it and barely a bump she fires right up. still sitting and sptting and sputtering a bit, whch was my initial problem, but sat and idles.....i wonder if this has been an isue for a while and since i didnt tilt it this weekend while i was out the problem showed its ugly face. when i trailer, i always have my motor up...so maybe i wouldnt have known?

 

[amoler821]

went back and tried again, it started and ran then stalled after 10 min. i could see the inline fuel filter half full of fuel now. i used the primer ball to pump it up, but it would get hard, then loose it and soften up. . it started leaking around the oil pump. took it off and the oring is blown out. since the oil pump runs off a gear on the crank, could this be sucking air in when running causing my rough idle?
when i initially broke down this past weekend it did the same thing, and i saw fuel leaking but figured it was flooded. now that im thinking about it, when i tilt my motor when trailering i get some oil/fuel mix in the outboard well.. could this all be related? i never noticed a fuel slick behind me while on the water.