50HP Yamaha won't start after storage

R

Robert Peyton

Recruit
Joined
Dec 2, 2009
Messages
3
Model: P50TL?S (One character unreadable.)
S/N: 517376
Code: 6H5 L
Believe this is 1994 Model and have purchased Seloc online manual for same.

Last time used - three months ago - motor ran well except hard to start and stumbled a little @ full throttle. Now will not fire a single time in normal configuration but starts instantly and runs for several seconds when "starting fluid" or gasoline squirted in carbs. Found some water in gas tank - cleaned tank and purged gas lines. Checked fuel filter. Replaced fuel pump. When bulb squeezed or motor turned over with starter gas runs from float bowl drains (with drain plugs removed) on all three carbs so I'm sure gas is getting that far.

I am guessing the water in gas and long storage has plugged up carbs. Is it reasonable to think that all three carbs would fail at same time? Is there anything else I should check before rebuilding them?

If rebuilding required, what is correct kit? Carb Mfg = Keihin Carb ID = BCP 6H512 1B19.

Thanks a lot for any help.

Bob
 
9

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,195
Re: 50HP Yamaha won't start after storage

The missing letter would be H for a tiller or a R for remote control. S is for 1994. Water and old fuel will cause lots of problems. Keep it clean and stabilized. Install a water/ fuel separator it will help a lot
I would pull the carbs, completely disassemble one at a time(especially if you have not done it before), inspect,and clean all passages and jets. Depending on what you find you may need to use carb cleaner and compressed air. put back together and adjust back to where you found them, (Count the number of turns from lightly seated on Pilot screws before removing)Some of the main jets are different size so make sure you put back where they came from.
Do not forget to do the same to the Prime Start system.
If you find things that need replacing get them at that time, These carbs have o-ring type of gaskets and usually can be reused if not too old and you do not tear them up while working with them
After reinstalling you will have to do a sync and link.
 
R

Robert Peyton

Recruit
Joined
Dec 2, 2009
Messages
3
Re: 50HP Yamaha won't start after storage

99yam40
anything
Thank you very much for your help. I didn't know about Prime Start until you mentioned it. I had wondered about the abscence of choke butterflies, now I am working to understand it.

I will follow you advice and attempt to rebuild the carbs with their existing parts and order one or more rebuild kits if some parts are not useable.

I have a good electric tire inflator but no stand alone compressor. Does anyone know where to obtain an adapter to use an inflated tire as a compressed air source?

Thanks again,

Bob
 
G

gill

Seaman Apprentice
Joined
Dec 10, 2009
Messages
42
Re: 50HP Yamaha won't start after storage

find out what color the kill circuit (engine stop) is and go around the engine up plugging each plug with that color in it. it also could be bad kill switch.
 
R

Robert Peyton

Recruit
Joined
Dec 2, 2009
Messages
3
Re: 50HP Yamaha won't start after storage

Gill,

Are yu referring to the fitting on the remote control that kills the engine when a cord is pulled off - sort of a man overboard swithc? That's the only kill switch I know of on my motor. If that's not what you mean, please give me a clue how to start looking for what you mean.

I'll searh my Seloc manual to see if I can find anything else, but I haven't found anything about the Prime Start yet and am beginning to wonder how complete the manual is.

Thanks for your help.

Bob
 
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