Hi, 2c...The OP asked how the crap got through the fine mesh standard filter. Well it didn't it was created in the carb. The crap got in there in solution, which means molecular size, ie. unfilterable. In normal use, an outboard
will suck the whole mix up and burn it. The impurities in the fuel
will leave deposits. IF the oil
you are using is not tcw3 rated, it will leave more deposits because 2t or m/cycle oil
is designed to not burn until it gets really hot, and outboards NEVER get to those temps unless there is something wrong. Tcw3 is designed to burn at a lower temp, and it might contain ammonia whose job is to attract water
and transport it through in emulsion. Also OB oil has an adhesive
additive to retard drying and run off.
Anyhow back to the OP, the stuff in your carb was made in your carb, and I have nothing against extra filters, save that it could retard fuel delivery
and induce air. If you leave your outboard
for longer than a month, disconnect the fuel hose, while running, then pull out the choke and open the throttle Wide Open, keep pushing and pulling the choke to control the revs to normal levels. When the fuel is nearly used up it will lean-off and the revs will increase, at this point pull the choke out and let it die. This will coat the inside of the engine
with a rich smear of oily gas, and will remove fuel from the carb. The gunk is a residue left over by evaporation, where the lighter fractions of the fuel mix disappear first, leaving ever heavier elements behind. IF you leave you hose connected (stoopid) it will pump more fuel in every day with diurnal heating
, all the non return valves in the system will see to that...the result is you can land up with essence of gasoline in the carb bowl, looks like treacle, and is best dissolved with methanol. (methylated spirit)
No filtration will stop that.....
WHILE I AM HERE....just a word of advice to all fellow croozers. If you are in the habit of tilting your motor
at night, please let it cool for 5 minutes in the vertical position before tilting. When tilted, the water
will not drain out completely. The residual heat from the engine
will evaporate the pools od water inside the engine, leaving salt
and calcium deposits, and will over time result in an overheating
Another another thing...the idle jet in most outboards will need to be replaced every 2 years or so in the Caribbean
or elsewhere where there is moisture in the fuel. It causes erosion of the hole to a bigger size. As the hole is so small (#45 on Yamahas) an increase of 1 thou is like 20% richer.
Symptoms will be difficult starting and a "sneeze" at idle. Quick fix is to turn the air screw out a half a turn, but get a new jet...you will love the difference.
Hope this helps......
Soo now you see what crap we learn while cruising...