225 merc 3.0 carb wont go over 3000

[dinghyworld]

The problem is it now wont go over 3000 rpm. It was running well, pulling 5600 at 60 mph. I have checked the manual and followed the setup for the tps, setting the correct voltages at idle and full throttle. The motor seems as if it may have been put together from several others, as ordering parts from the serial no (OG051279) didnt get all the right parts for the leg. It only has a warning horn, no idiot lights are fitted. The manual indicates that the only other sensor to cause this problem is the water temp sender, but the resistance readings seem ok. The motor on muffs sounds great, but on the water it will not go over 3000. Does anyone have some tips to fault trace this problem?
Many Thanks
John

 

[router343]

Re: 225 merc 3.0 carb wont go over 3000

I have a 150 HP Outboard, kinda have the same problem, it was mentioned to me that it could be a high speed jet clogged on one of the carbs, not sure if that helps you any.

 

[Faztbullet]

Re: 225 merc 3.0 carb wont go over 3000

Check to see if timing is advancing above 10degrees when you increase rpms, if not the ECU could be faulty( if ECU fails the stator will take over but at reduced power)

 

[dinghyworld]

Re: 225 merc 3.0 carb wont go over 3000

Hi Guys, thanks for the info, we put the timing light onto it and ran it up, and the timing was way out, did the check of the pointer position and we could not get enough adjustment to line up with the .526 mark. We were about 8 degrees out! Removal of flywheel revealed a nearly sheared key. I have ordered a replacement, and I will let you know how it goes.
Cheers John

 

[dinghyworld]

Re: 225 merc 3.0 carb wont go over 3000

Update, new key fitted to flywheel, carb clean and 5500 on tach, customer couldnt be happier.
Cheers
John