115HP low RPM stalling

[cigar_stub]

My Yamaha 2002 115hp outboard is giving me fits at low rpm, mostly idle speed. It starts fine and runs like a top when above idle, which as about 800 rpms. But when idleing it sounds like it's missing a beat (new plugs only 5 run hours ago). I had brought it to a mechanic a month ago who said he could find nothing wrong, it was running great. But if it does stall, it then becomes very hard to restart. Once started, when I give it throttle, it may start fine and I can run at 30-33 mph at about 5500 rpms (my listed WOT)with no problems. Or it may bog down as if it has no power and stall again. It's very frustrating. My neighbor gave me some gas treatment (1oz per 6 gallons) which he says will help clean the engine a bit which may help. The gas is clean (I have a fuel/water filter in place).

Any suggestions? Thanks in advance for any help. I mistakenly posted this in the Mercury area earlier today.

 

[skynyrdcat]

Re: 115HP low RPM stalling

Sounds like it may be getting too much fuel in the bowl.

Did you winterize the fuel system last fall or did it sit the winter w/ fuel in the carbs?
The carbs may need cleaned (specifically the needle / seat).

 

[Yamajoe]

Re: 115HP low RPM stalling

I agree with the post you should also check for airleaks and or restrictions in the fuel lines from the tank through to carbs, it is amazing what a little bit of air sucking into the fuel system can do to idle and wot operations; when the carbs are cleaned dont forget to check timing and link and sinc.

 

[cigar_stub]

Re: 115HP low RPM stalling

Thanks for the input. I did not drain carbs because I used gas stableizer and used the boat about every month or so on a warm day. I don't think it sat more than 6 weeks without being run.

 

[douglloyd]

Re: 115HP low RPM stalling

Carbs need to come off for a full cleaning.
Sounds a lot more complicated than it is.
Start there. $250 labor.
Do a search on dirty carbs that should convince ya.

 

[cigar_stub]

Re: 115HP low RPM stalling

Well I went to the lake today and was going to run it around, but it was raining and cold so I so I just left the boat there for the mechanice to look at. I'm not familiar enough with the carbs to attack them on my own.