Mercury 3.5 four stroke idle and running problems

[aboyfromkansas]

I have a 2006 Mercury 3.5 four stroke engine. SN #OR142017, Model 1F03211HK. When I start the motor using full choke, with the throttle in the start position. The engine will run rough and as I close the choke, the engine will go to a high RPM sometimes. Other times I am able to fully close the choke if I advance the throttle and control the RPM that way. In most cases, the engine will not idle, when it does idle, usually rough and at a slightly higher RPM, it usually quits. When I attempt to restart the engine, it again will only start using full choke, then the same scenario is repeated as described above. I have researched this on the internet and this is a consistent problem with this engine by other users. In most cases, it seems that the carb is the culprit because of dirt and the tiny jet orifices that clog easily. Carb cleaning has been recommended by local shops, but I would think this problem would soon come back. Looking at your website for a carb replacement, It looks like the replacement carb for this SN and Model, is #898103T51. Is this an upgraded or improved carb? Do you think I should have the carb cleaned, or would replacement be a better alternative? Also, does 87 OCT fuel with no more than 10 percent Ethanol make that much difference? I did try using a small amount of Seafoam added to the fuel. Also checked and cleaned all fuel lines and checked the fuel filter ahead of the fuel shutoff valve. Comments would be appreciated.

[boats.net]

Probably just need to remove and clean carb, gas goes bad in carb and turns to varnish plugging jets and passages. Using fuel stabilizer helps, using non-ethanol gas helps.

[aboyfromkansas]

Mercury 3.5 Idle and running problems

Thanks for your suggestion. I have only had this engine for a short time, but I'm still a bit cautious about a permanent fix. In reading about the problems other people had, in some cases, the motor ran fine and then out in the middle of the lake, the motor would not run or idle. Three people I read accounts of them taking new motors back and the dealer gave them new motors. Shop rate is 95.00 plus 57.00 + tax for overhaul kit for cleaning.
Replacement carb 199.64 plus 17.00 shipping on your website. If I knew the new carbs were improved, I would go that route. Maybe have the old one cleaned and packed on the boat. That way I could change it out on the boat if I got stranded. Thanks again, great forum.

[boats.net]

Couldn't say without knowing exactly what problem is but if it is a gas problem then new carb would not be any improvement. If carb has a defect then yes new carb would be an improvement.