2004 Yamaha 115 question

[gregga]

Hey guys,

I have a friends boat at the house that has a 2004 Yamaha 115 outboard. The boat sat for about 4 months and he took the boat out last Saturday and as soon as he hit mid RPM range it would bog down real bad and wouldn't turn up anymore. I do not know too much about outboard motors but I can guesstimate after sitting for 4 months with 3/4 tank of fuel that it may have to do with a fuel/water problem? Any help is greatly appreciated... Thinking about pulling air cleaners tomorrow and spraying the carbs with carb cleaner then dumping in some fuel additives and letting her idle on the hose for a while. After that I do not know as far as pulling carbs and having them rebuilt? thank you guys.

 

[99yam40]

Re: 2004 Yamaha 115 question

Hook up a portable fuel tank with fresh fuel and flush the old fuel out of carbs, lines, and fuel pumps.

If it will not run properly at that point then you will need to pull and clean carbs.
Shooting cleaner at the carbs will not do any good and running motor and hoping can cause damage if it is running lean or with old bad fuel

 

[Bamaman1]

Re: 2004 Yamaha 115 question

+1 on the above suggestion.

Pulling the carbs off a 115 hp Yamaha is a pretty easy project. If you're careful with the gaskets, no carb kit will even be required. I would suggest that a service manual be purchased, however. You've just got to screw any adjustment screws to the right noting the required turns before turning them to the left (to remove them.) You'd re-adjust the engine to the original number of "turns". Also pay especially close attention to the needle valves making sure they're working smoothly--often the culprit of rough running.

A dealer would charge you something like 3 hours labor. I think I spent just over an hour last time I pulling my carbs cleaning and reinstalling them. My total investment was a spray can of carb. cleaner--$4.

While you're at it, I would suggest spending $17 for a new rubber membrane for the fuel pump and taking apart the fuel filter under the oil tank to make sure the element is clean.

That old 90/10 gasoline just doesn't have much shelf life. When it separates, an acid is produced that will eat rubber.

 

[Capt Ken]

Re: 2004 Yamaha 115 question

Normally if the engine idles good and acts like you describe, the carbs are ok. The low speed jets are much smaller than the high speed jets and will plug quicker. If your timing arm on the side of the engine is advancing fully, I would look next at the fuel pump or a restricted fuel line.

 

[ohabu]

Re: 2004 Yamaha 115 question

Alternatively it might be an electronic halt - those are usually recognizable by feeling like a rev limiter compared to a carb/gas problem where it would usually be a lot less consistent with the bogging down. Check oil, oil pressure switch.