gummed up carb

I recall some unlikely post (not here) by someone who boiled up the carb for an hour or more in water spiced with lemon juice....... Swore it to be totally effective!

Anybody tried that? My Yamaha 2.5 gums up with the least provocation.
 
Why not try carb cleaner?????
I've found trying to run the carb dry causes more problems than not. I reckon it will never be completely dry but leaving less in the bowl means less to evaporate and cause more gumming up.
 
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Its snake oil. Take it from someone who has cleaned literally hundreds of blocked outboard carbs, the most important factor is where you squirt the fluid not what the fluid is. I use the cheapest carb cleaner that is available at the time.
 
Spyro said:
Why not try carb cleaner?????
I've found trying to run the carb dry causes more problems than not. I reckon it will never be completely dry but leaving less in the bowl means less to evaporate and cause more gumming up.
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Thats the reason you have drain screws on the float bowl. Due to the design of a float carb you will never ever run one dry
 
Spyro said:
I've found trying to run the carb dry causes more problems than not. I reckon it will never be completely dry but leaving less in the bowl means less to evaporate and cause more gumming up.
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I don't really follow that. :confused:

If the outboard is going to be left long enough for the petrol to evaporate completely however much you start with, surely it's better if the evaporation process starts with as little fuel in the float chamber as possible.

I can see that if the carb is not going to evaporate to dryness then it's probably better to leave it full or, ideally, drain it through the carb drain.

Richard
 
RichardS said:
I don't really follow that. :confused:

If the outboard is going to be left long enough for the petrol to evaporate completely however much you start with, surely it's better if the evaporation process starts with as little fuel in the float chamber as possible.

I can see that if the carb is not going to evaporate to dryness then it's probably better to leave it full or, ideally, drain it through the carb drain.

Richard
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The trouble is if you leave it full what fuel you have in the float chamber is not sealed and will go stale. You may have a nicely sealed fuel tank but it will never start with stale fuel in the float bowl unless you add additives
 
No-one has ever been able to satisfactorily explain to me why outboard carbs gum up and lawnmower carbs don't. My Honda lawnmower gets left with a full carb of petrol in winter, and five months later it starts on first or second pull. Similar sized engines with similar sized carb jets - what gives?
 
RichardS said:
I don't really follow that. :confused:

If the outboard is going to be left long enough for the petrol to evaporate completely however much you start with, surely it's better if the evaporation process starts with as little fuel in the float chamber as possible.

I can see that if the carb is not going to evaporate to dryness then it's probably better to leave it full or, ideally, drain it through the carb drain.

Richard
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I think the problem is evaporation. It leaves behind some gum. If you evaporate salt water it leaves salt, same idea.
 
fredrussell said:
No-one has ever been able to satisfactorily explain to me why outboard carbs gum up and lawnmower carbs don't. My Honda lawnmower gets left with a full carb of petrol in winter, and five months later it starts on first or second pull. Similar sized engines with similar sized carb jets - what gives?
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Is your lawnmower stored 3 feet above the water, subject to dew nearly every night? Or is it away from the water, inside a shed with a door? It is the water in the air that makes the difference.

Perhaps the most common error is to leave the breather open on the small outboard tank. A few good rains and there will be enough water to start corrosion. It is the corrosion and emulsions that get you, not actual gum.
 
Spyro said:
I think the problem is evaporation. It leaves behind some gum. If you evaporate salt water it leaves salt, same idea.
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Exactly .... so if you partly drain down the carb by running the engine until it stops you reduce the volume of fuel in the float chamber and therefore less gum is left behind when the fuel evaporates. If you leave the float chamber full of fuel you get a much larger amount of gum residue left behind, just like salt water.

Richard
 
I do it I charge £25 for a carb ultrasonic clean rebuild and reset on an engine. You can do it yourself if you have a cleaner and its big enough. I use an industrial cleaner
 
steve66 said:
I do it I charge £25 for a carb ultrasonic clean rebuild and reset on an engine. You can do it yourself if you have a cleaner and its big enough. I use an industrial cleaner
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hi all - while all this being discussed - is it poss to buy ss replacement nuts for bottom of bowl etc which wont corrode / is this even desirable? anyone recommend good supplier of gaskets / o ring for bowl (thinks there's one) etc for replacement of bits after cleaning carb ? any general 'good egg' as a bits supplier for our honda 2.3 (couple years old) -
thanks (all very interesting)
 
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