50hp Starting/idle issue

[MrBigbird]

Hello I am new to the forum and see that you guys all seem pretty on top of it here. My question is as follows.
I have a 2006 Yamaha 50hp 2 stroke on my Palm Beach 151 boat. The motor has around 80 hours on it. I am usually pretty good about starting it up every couple of weeks if I have not had the time to run it but for last 2 months I have been lacking. I went to strat it last weekend and no dice. I changed the fuel filter, installed new plugs and drained the card bowls. When I filled it up last (it still has a full tank) I put some Stabil in it as well as Seafoam, it has a 20 gal tank, in with the gas. It still will not start unless you advance the throttle half way and then it will only idle around 2500rpm's. If you take the cowling off and turn the fuel enrichment lever to the open position it will idle and run but as soon as you turn it back to normal it dies. When it dies it will cough and sputter then just die. I took out and put it in the water the other day and got it started but it had no power would not go over 3000rpm's and as soon as you turn the enrichment lever to normal it would cough and die.

If you take the air cleaner box off and cover the carb throats with your hands the top 2 will bog for a sec and then pick up and take off. The bottom carb just sputters and dies killing the engine. The bottom plug is also varnishing up extremely fast.
Can you guys please help!
Sorry for the long first post.

 

[rodbolt]

Re: 50hp Starting/idle issue

remove the carbs, dissasemble and carefully clean said carbs, reinstall and go play.
if you continue monkeying trying to make it go you WILL post about low compression and scuffed pistons and the carb job will get done at the piston replacement.
put all the snake oil you desire in the fuel, bottom line is todays fuel simply sucks and there is nothing we can do about it and I suspect its only going to get worse.
if your gonna let the rig sit any time then simply drain the bowls after using it.

 

[MrBigbird]

Re: 50hp Starting/idle issue

Sorry if I am sounding a little stupid but when you say clean the carbs do you mean a rebuild of them or just removing the bowls and cleaning with some cleaner and compressed air? Should I quit using Stabil in my fuel or no? I thank you for your reply.

PS
Is there a place to buy the carb kits online if I have to do a complete rebuild?

Thanks again

 

[rodbolt]

Re: 50hp Starting/idle issue

quite often we can simply dissasemle,clean and reasemble the carbs reusing the seals.
however that is a case by case basis and your looking at them while all I have is a monitor and 30 yrs of experience.
dunno about carb kits online.
if you buy the kit remember it comes with nothing related to the prime-start portion.
while stabil is recommended I find that with todays fuel its not very effective.
mostly due to we dont know how old the fuel was when blended with ethanol to start with nor how long its been in the distribution pipeline before it got to your fuel tank.
my reccomendation now is simply drain the carbs after each use just in case something comes up and the boat gets left out back a few months. it happens.

 

[MrBigbird]

Re: 50hp Starting/idle issue

Thank You again for reply and help it is greatly appreciated and I am also thankful that someone with your experience is willing to share their wealth of knowledge.
I will have help to do the required action as I have a family member who is a ASE Master Mechanic from back in the day who learned alot about carbs from engine guru Ray Fox and he has said that they are not much different to him.
I again thank you for your time and money saving advice.

 

[rodbolt]

Re: 50hp Starting/idle issue

the carbs on that engine are very simple.
except maybe the variable venturi carb that ford ran some years ago carbs are pretty much carbs and rely on intake vacum and atmospheric pressure to work.
aint but so many ways to make a carb.
be aware on your 50 that correct linkage setting is critical for proper prime start operation.
its not hard just need the correct manual and go for it.

 

[MrBigbird]

Re: 50hp Starting/idle issue

Thanks again for your help. Will have to reset the linkage or will it come off and go back on the same way without being reset? If I do have to buy a manual what one do you recommend? I thank you again.