Petrol Gunge

[Lakesailor]

Had a nice day out in F3 yesterday until the wind died about a mile from home. Absolutely gone. Started the outboard and chugged along for about a minute and it stopped.
Put the sails back up and ghosted along back and sailed onto the mooring (beautifully done, if I say so myself). It was far too hot to do anything about the motor, so I went back out after tea and stripped the carb. I found some creamy-coloured jelly-like deposits in the float chamber and blocking the main jet.
Any idea where these have come from? Is it a constituent of modern unleaded fuel? It's a 4 stroke so it's pure petrol.
I cleaned the carb out in December when I replaced the needle valve.
The only other thing I can think of is that I got a new plastic fuel can a few weeks ago, but how does the slime it get past the fuel filter. Is it just a residue left after the fuel evaporates in the hot weather?

Any ideas?

 

[Kawasaki]

Probably sat for a while after the needle valve jobby. Although it,s a four stroke petrol still "gets at" the bowl. Sometimes after you,ve cleaned it there could be the residue off the rag or tissue or whatever you used to give it the final wipe. As you say crap shouldn,t get passed the filter. Stick it back in the water and give it a good blast. If it still persists chuck the petrol and start again with another batch. Strain it through summat clean, then your certain there,s no gremlins getting in. Finnicky sometimes these little sods!

 

[VicS]

Tip for straining petrol, but where did I see it? It must have been in the article on outboards in PBO.

Use a paper coffee filter in a plain funnel. It should be good for removing any water contamination.

 

[Lakesailor]

Ah no. I didn't explain. I've used it at least fortnightlyly for leaving and approaching the moorings and did a 2 hour trip down the lake in a calm the other week. But I've just taken to tilting the motor up out of the water when sailing and wonder if it's encouraged the slime to migrate to the main jet.
It has an internal tank which I use all the time, which only hold a litre, so the fuel doesn't have chance to get sick in the tank.

 

[Kawasaki]

Strange one that then? "Tilting" shouldn,t be a prob considering the usage latterly. Good swill out of the tank. Also unless its already got one, small in line filter(motor bike shop) in the fuel line, can,t think of owt else!

 

[Lakesailor]

I think you're right about a new filter.
Thinking about it now it would have been worth dropping the anchor and hauling the motor into the cockpit as it only took a few minutes to fix.
But it was so damned hot.