Re: What is this supposed to do?
It dumps gas that puddles in a couple locations overboard. FYI, the locations it picks up from are just behind the top reed set (the one on the left) and just left of the bottom of the lower crankcase chamber. It is a waste of gas, and some people have tried some setups to recover it. But, by reports, if your engine is tuned correctly, it is not worth recovering. Modern outboards recirculate this gasoline rather than dumping it, usually putting it in through one of the intake covers or into the intake manifold.<br />The drain valve assy is a pair of one way valves to pump the gasoline from those two puddling locations. Crankcase compression pulses pushes the gas through them, and they don't allow it to be sucked back.<br />So, it's doing exactly what it's supposed to do. If you have excessive fuel puddling, it may be because you are running too rich. Since your carb is fully adjustable, you should be able to correct that easily enough.<br />The passage that is leaking on your outboard is connected to the 'just beneath the left reed' puddling location.<br />My OEM manual makes almost no mention of it except how to take it apart and clean it.<br /><br />
Further reading.
