Please help me identify this port

[imported_stump jumper]

My 200 Mariner started making a sound like an exhaust leak. I pulled the cowling and found this port was the culprit. There is a clamp around a bit of hose, I don't know if this was capped off or if it went to something. Thanks for looking and I appreciate the help.
http://s189.photobucket.com/albums/z55/jhalbrooks123/?action=view&current=S6300591.jpg

http://s189.photobucket.com/albums/z55/jhalbrooks123/?action=view&current=S6300590.jpg

 

[gss036]

Re: Please help me identify this port

That looks like the connection for the poppet valve, which dumps into the exhause port. That would account for the exhaust sound. There should be a hose coming from the top of the block, which feeds water to the poppet. The poppet opens at about 2300 rpm to dump excess water overboad thru the exhaust. If there is no water in the lower cowling then look at the below sceneiro.
If not the poppet, then the opening in the block that provides the pulse pressure to pressurize the oil tank on the boat, which pressure feeds the tank on the engine. There should be a check valve that screws into the block. I can't tell for sure w/the pictures though.
After taking a second look w/picutre enlarged, I would say it is the pressure feed for the oil tank. There should be a loose line laying there. Trace the lines from the oil tank. It looks one of them is going up to the oil tank on the engine.

 

[imported_stump jumper]

Re: Please help me identify this port

i am premixing my fuel, can i just cap this?

 

[gss036]

Re: Please help me identify this port

YES. Is the oil pump removed and gear probe removed from the hole? And a cap over the hole?