Yamaha C115 Ready to Pull My Hair Out!!

[whitestar]

1991 Yamaha C115TLRP
Began the season, prepare the boat, new gas, ran fine on trailer....put in water, after banging around on ocean, it coughs, spits and runs rough (not that nice-smooth sound).
Pulled boat out, removed carbs, cleaned them out and reinstalled. Drained the tank, fresh gas too. Got my nice smooth idle back. Used boat for appx one hour and began to run rough as I approached my mooring. Coughs, spits and stalls again.
Yesterday I could only start it by using the manual choke, and could get the engine running constantly at 2000 rpm but running rough (shaking) and did not have that nice smooth sound.
When I bring it down to an idle it shuts right off on me.
I read somewhere here that could be caused by faulty thermostats?? Doesn't make sense to me but I tested them earlier. They are 3 years old but still open and close.??
Also beginning of season, tried new filter/water separator. Larger one (Yamaha Hi Performance 90 GPH/10 micron.)
Also notices something strange yeaterday, upon first startup, I could not get the primer bulb hard. Worked fine after the motor got started. Noticed no gas leaks. Maybe an air leak in the line?
Does anyone have any ideas?? I'm about to flip my lid over this!!

 

[Ray Neudecker]

Re: Yamaha C115 Ready to Pull My Hair Out!!

You do appear to still have a fuel restriction problem. If you haven't changed the fuel pump, now is the time. Also check the anti siphon valve in the tank as well as the fuel line including the bulb.

 

[whitestar]

Re: Yamaha C115 Ready to Pull My Hair Out!!

I removed the fuel line at the filter and blew into the tank....actually I could NOT blow air into the tank. Does this mean the anti-siphon valve is good??
The primer bulb is a few years old and so is the fuel pump.
I've almost resolved myself to think that it is the ethanol in the fuel, but it can not possibly be reacting that way because of gas. It's been a very robust engine all these years and I've always had some water in the tank but it never reacted this way before.
Every year since they put ethanol in the gas, I've had to clean out the carbs...always did the trick but not this year.
Will replace fuel pump and primer bulb this week.

 

[Scout Sport Fish]

Re: Yamaha C115 Ready to Pull My Hair Out!!

Try changing the fuel water seperator on the fuel line.