Yamaha DETO 50HP 2 stroke (3 cylinders)

[sticka360]

Hi to all !!
I need of help I have just purchased the engine above. It starts first time & sound ok for a while on tick over, when revving sometime misses (intermitent). When in the water it will run for a while then start missing and jump around and firing on different cylinders. Also on nearly full throttle the engine will go along very well & sound good, then after a while it then cut to firing on 1/ 2 cylinders !!!!! My mechanic has set the timing up 3 times, when setting up to ok, the engine will then start jumping all over the place !!! He has cleaned the carbs twice and still doing the same !! Mechanic tells me it could only be 2 things CDI unit has gone or.... the crank is out !?!?!? He tells me it could be either of these things Please, please, help !!!

ps - Also the ball from the fuel tank never gets hard ?? could this be the problem fuel starvation or to much, sounds like fuel goes back into the tank sometimes also ???

sticka360.

[dorf]

Why not try a different portable fuel tank and different fuel bulb first ???

I have an inboard fuel tank and the anti-siphon valve was sticking plus the Yamaha fuel bulb was defective. Now using a Bombardier fuel bulb and removed the anti siphon valve. Now all OK.

[sticka360]

Thanks

Dorf,
Thanks for your help, the fuel ball was not getting hard & air was sucking into the fuel tank, the carbs where also full of nasty bits !!! Though cannot get the timing advance & fuel settings right. Can any one help me on what the settings should be on the timing light & fuel / Auto lube settings should be ? Have tried to get a work shop manual for this engine & have fail terribly !!!

Again thanx for your help !!


Regards

Sticka360

[dorf]

I purchased a Clymer Manual .Lots of instructions and pictures.( # B786)

Someone else suggested the following for $9.00, seems too good to be true though, in my opinion ???

Yamaha Service Repair Manuals, Download Service Repair Manual Instantly only $9.99 each!!