Outboard trouble

muckypup

muckypup

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Started up my Yamaha 4hp 2 stroke outboard for the first time in a while today. She started up nice, revs fine. Pee hole pees. Plenty of exhaust gas and some white smoke. Problem is that if I put it into gear either forward or reverse and open the throttle the engine bogs down and will eventually stop. The prop turns at idle, it's just when I give it some revs in gear.

Anyone have any ideas what might me wrong?

Thanks
Steve
 
That sounds like fuel starvation. The fact that you say that the engine has been started "first time in a while" is a clue. Do you always run the carb dry when you are storing the engine? If not, it is quite possible that the jet has gummed up a little with fuel deposits (stick stuff when petrol/oil mix evaporates. You probably need to clean the carb out and blow through the jet with some compressed air.
 
Take care when taking out the jets . Previous owner F***d them up so icould not remove them , Eventually had them sonically ( cleaned by sonic , whatever ) cleaned at a cost of £150
 
If you remove the main jet (small brass screw found on underside of top half of carb when the float bowl removed)
once this is removed you will see the the emulsifier tube in the hole where the jet came out from.
This emulsifier tube is what meters the fuel mix from just above tickover to full revs, it has rows of tiny holes down along its length, these are the holes which get blocked very easy, 1 strand of wire pulled out from a wire brush with a pliers will help to clear them out.
If they are blocked/gummed up with varnish residue, boil them in a pot of water for a while, it will soften the gum, which can then be flushed with solvent/petrol etc.
 
[ QUOTE ]
1 strand of wire pulled out from a wire brush with a pliers will help to clear them out.

[/ QUOTE ] NO dont use a steel wire. That can damage the jets, Use a piece of soft copper wire eg fuse wire.
 
As other posts suggest, sounds like either a blocked main jet or fuel starvation, the latter through either a faulty breather or clogged filter. Main jet a doddle to remove and clean, best with an air-line. As for spending 150 sovs on cleaning jets...they cost almost nothing, (and I've got a box-full at home from the old 2-stroke racing days...pause for nostalgic grin). Are they really that hard to buy?
 
Ah yes. I remember the days when I was 17, I had a Yamaha 125LC motorbike and I used to experiment with the jets in the carb to try and get more power! Sounds like a job I might be able to have a go at.

Steve
 
[ QUOTE ]
Did you do the Ray'sd?

[/ QUOTE ]

Remind me what a Ray'sd is ? /forums/images/graemlins/smile.gif

S.
 
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Before you go to all that trouble give the carb a good spray with carb cleaner it might just do the trick. It certainly dissolves petrol residue.

[/ QUOTE ]

Any idea where I can such a magical spray?

S.
 
[ QUOTE ]
[ QUOTE ]
Before you go to all that trouble give the carb a good spray with carb cleaner it might just do the trick. It certainly dissolves petrol residue.

[/ QUOTE ]

Any idea where I can such a magical spray?

S.

[/ QUOTE ]Halfords? A motorbike shop? What is usually sold as Carb Cleaner is - I think - isopropyl alcohol. Or maybe that's brake cleaner.....
 
Don't know about you, but I gave up believing in magic about the same time I realised Santa was really dad.
Do a proper job. Whipping the bottom off the carb and unscrewing the main jet takes takes minutes.
And if the problem's a blocked fuel line or breather vent, carb cleaner won't do a damn thing anyway.
Not least, next time the outboard gives trouble, miles from a web connection or Halfords, you'll have an idea what to do.
 
ahh, sadly in some ways, isoprpyly isn't what's in em, or they'd work rather better than they do on stubborn gum.

that stuff can & does degrade rubbery seals n o rings tho, which may be why they don't major on it, But, it is superb at cleaning the thick varnishy deposit that can clog jets/passages after fuels been left to evaporate many times. Just avoid the seals, altho some won't be affected, it's a bit late afterwards & they can be a devil to obtain.
 
Well, I popped the top off the outboard this afternoon. I had to remove the air filter and carb complete to get to the bowl. It was full of brown crud, and so was the jet. One good clean and reassembly later and it now works perfectly. Thanks for the good advice everyone!

Steve
 
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