merc 90 hp 4 stroke carb question

O

oteps

Senior Member
90 hp 4 stroke on a pontoon. It has a stumble at low rpms and I was thinking of pulling the carbs off and cleaning them. But cant find a carb rebuild kit. Buying all the o rings and parts from merc is expensive. I really don't want to clean everything and reuse float and intake o rings. Any ideas? Or just deal with it? Its not my boat, just take care of it and a small cabin on the river for some friends.
 
One of the smart guys will be along, but i d run some sea foam through it. I never had much luck with ***8220;mechanic in a can***8221; products, but sea foam has helped on some issues like this. I m guesssing your using non ethanol and have put in fresh fuel filters.
 
I reuse those o-rings all the time. If you need parts, its probably easier to get them for a Yamaha 90(same power head) Clean the needles and seats. IF you don't have a vacuum gauge set up, don't try to do it without one. They are very finicky. Dont use harsh chemicals to clean them( I use an ultrasonic cleaner). I you carry it to a shop, be prepared for sticker shock. BTW, those carbs are $700 each new.
 
I have a vacuum carb sync tool. I used to work on motorcycles, I would think its the same thing. I have a bunch of different adapters to screw into intake.
 
if you know how to use one, then it shouldn't be a problem. Bottom carb is the master carb, set the idle mixture screws back in the same place
 
looks like it has a plug over the fuel (idle) mixture screw. Drill and put a screw in and pull out is what I did on bikes. Supposed to be warm this week I might get time to pull carbs off. In 2 weeks the boat will be in the water for the summer and I don't want to do it sitting at the dock.
 
Pay CLOSE attention when you do them to get ALL the fuel circuits cleaned out when you do them. Some of those carbs have 4 fuel circuits(my Honda had 4, talk about a PITA). Sometimes there will be 2 or even 3 fuel pickups for the jets too, so make sure you get them all.
 
Hey ferm let me know if there is a house for sale next to you, I'm going to move there with my 1988 merc You can keep her running for ever
 
pulled carbs off today between rain storms. Will clean them tomorrow. Thanks for all the advice. Docks at marina go in Thursday and have a week to get boat out of their storage lot and in water.
 
got the carbs cleaned. 1 float is lower than the other 3. I cant find any info on what the level should be. Im just going to adjust it to the same height as the others. ??
 
Im going to leave them where they are at. THey are not as easy to adjust as motorcycle floats. Looks like they will break.
 
You must log in or register to reply here.
Back
Top