Old Problem that will Not Go Away!!

[fishfun83]

My 1996 C80TLRV 2-stroke is giving me fits. I have posted my problem(s) before but they keep coming back. My engine cranks fine but "most of the time" dies when I give it gas. To date, I have purchased a small fuel tank (5 gallons) in order to isolate the built in fuel tank as the problem, I have purchased a new OEM Yamaha fuel hose and bulb, I have changed the fitting the hose attaches to at the engine, I have replaced the fuel pump, I have replaced the fuel filter, I have rebuilt the 3 carburetors and replaced the spark plugs. The last thing I did that made the motor work correctly was to adjust the carburetors. Seemed to help but the next time out, the motor died when I gave it gas. Same old problem. I pulled the boat from the water to repaint the bottom and would really like it to run like it is suppose to run prior to re launching but I am running out of patience. Any other ideas I can try before I take it to a certified Yamaha repair center?

[Jason2tpa]

Did your carb rebuild include pulling jets and clearing debris/gunk?....install then time and sync?

[fishfun83]

Yes I did clean the jets but I do not know what is meant by "sync". I cleaned the carbs and adjusted the idle screw out by the recommended number of turns but that is it.

[99yam40]

service manual for your motor will have the link and sync procedure.
it is very important to follow the procedure each time you put the carbs back on the motor

[fishfun83]

Thank you. I did not know the carbs needed to be synced. I will look into that.

[TownsendsFJR1300]

Yes I did clean the jets but I do not know what is meant by "sync". I cleaned the carbs and adjusted the idle screw out by the recommended number of turns but that is it.

How much crap / varnish did you find in the jets?

Did you clean the carburetor bodies themselves? It sounds like there's crap/varnish in the body of the carb itself.


There's no C80 in the US, closest is an 85HP. Here is the carb parts list/breakdown: https://www.boats.net/catalog/yamaha...lru/carburetor
Should be pretty similar carburetor wise. Might want to make sure you got ALL jets out, preferably clean the carbs in an ultra sonic cleaner.
If not available, carb cleaner thru ALL orifices with pressurized air.


.

[fishfun83]

service manual for your motor will have the link and sync procedure.
it is very important to follow the procedure each time you put the carbs back on the motor

I purchased a Service Manual and find no mention of a sync procedure.

[99yam40]

I am not sure where it would be located right off the bat, but once the carbs are put back on then you have to close all throttle (buttrflies)plates/discs and lock them into place on the linkages so they are all synced together and then go about adjusting the idle speed and fine tuning the carbs & timing to specs

Is your service manual one from Yamaha or some after market one?