ready to burn this 9.9

[ron53]

Hi I have a 9.9 1987 yamaha o/b that will run at idle and when you give it throttle it dies and stops running...I've got the carb off and in the tank waiting on two diaphams to install in it.If this dosen't work any of you yamaha techs have any input.I inherited this motor from another marine shop and they couldn't get it right so I'm stuck with it...ron53

 

[noelm]

Re: ready to burn this 9.9

I am no expert on that particular motor, but there is some very basics that need to be taken care of first, do a compression test, use a complete new tank and hose with fresh fuel, have a look at the plugs, are they both the same, are they dry or wet, do you have spark, does the timing advance when the throttle is advanced, make sure you get a complete rebuild kit for the carbies and do not just wash them or spray some sort of miracle can of carby cleaner on them, do the easy but very basic stuff first. Also buy a GENUINE manual for that motor!

 

[ron53]

Re: ready to burn this 9.9

Thanks Senior Chief Petty Officer...what would you consider the compression should be give me the lowest value in psi...and thanks again

 

[jeffersondodson561]

Re: ready to burn this 9.9

Is this the 9.9 4stroke?

 

[noelm]

Re: ready to burn this 9.9

Did they make a 9.9 4 stroke in 1987? the actual compression numbers are not the most important part (well unless they are really low) because that can vary from test gauge to gauge, but it should be fairly even, what I am getting at by suggesting you do the very basics first is, you have no idea what has been done before you got the motor! you need to be sure the very simple things are in a known good state, or, you may be chasing a self inflicted fault before you ever get to look for what was actually wrong with the motor before it was played with, get what I mean?