2009 20 HP mercury 4 stroke bogs at half throttle and above

[charlie_diebel]

I have this Merc that is seemingly unfixable. The unit bogs once I get about half throttle and above. I have the service manual and have checked everything for proper pressures in the fuel system and its related parts. I have had the carburetor ultrasonic cleaned...I have replace plugs....verified proper resistance values throughout the electrical system and related parts. I have made sure all of my hose fittings are good and tight...I have replaced the accelerator pump...pulled the oil pump and measured the maximum range space tolerances within the pump, they are within specs...my next thought is the CD unit. From what I can tell, is that this unit automatically adjusts the timing of the engine during throttle up and throttle down.... IS there ANY way to have that CD unit checked out to see if it is any good before I go and throw a couple of hundred bucks into a new one...only maybe to find that was not the problem at all? OR what else should I be looking for? The unit starts like a champ..idles perfectly...evens revs up to a higher speed when I have it in a huge barrel of water....but when I take it to the lake and give it the gas....it decides it going to bog at half throttle and above I have not checked the unit out with a timing light as of yet. I am completely open to suggestions...thank you! Its a model 1F20201HK Serial: 0R298622

According to Mercury there are 5 reasons why this unit cannot get above 3000 rpm, they are as follows:

1) Low oil pressure
2) Ignition charge coil
3) Ignition coil high tension leads
4) CD unit
5) Spark plugs

In anyone of the above items where I could do a static resistive measurement, all readings were within specification according to the service manual.... The ultrasonic cleaning was done with carburetor completely disassembled..there wasn't a piece left attached to the carb when everything was cleaned. I am guessing that would be an extremely reliable, effective cleaning job done on the carb.

The only thing I have not checked is the CD unit, simply because I do not know how....is there any way?

Thank you for your help...it will be extremely appreciated.

CD

 

[charlie_diebel]

The fix....I apologize for such late response...maybe it will help someone. The motor was carboned up...used a spray can of Mercury PowerTune as directed....motor runs like new. Mercury support said carbon build up on their 4 strokes is a fairly common problem.