2004 250 EFI - internal oil tank leaking

[KenO250explorer]

Guys,   on this motor,   the internal oil tank is leaking out of the cap when the engine is running -  the tank was replaced in the last monht and Cap (i believe) were replaced along w/ the sensonr.    
Q for those smarter than me -  what is the mechanism for filling this internal tank -   is it a constant pumping from the "holding" tank external to the internal tank underr the engine cowling,  or is there a sensor that turns off this pump?    Any suggestions to trouble shoot?   Thanks

[CLM65]

What engine (brand)?  

My Yamaha has a level switch in the engine-mounted tank that activates the pump in the larger boat-mounted tank.  The pump turns on at low level and turns off at high level.

[KenO250explorer]

Sorry,  it is a mercury 250 EFI

[GoneFission]

The tank is filled by the pressure hose from the engine to about 2 psi.  The engine pressurizes the main tank, then the oil goes from the main tank to the aux tank at the engine.  The caps are famous for cracking and breaking if you over-tighten them.  Just get a new engine tank cap, hook up the two wires, and you should be OK, but don't over tighten!     I think the part number is 36-43300A9.  Should be $60 - $100 depending on where you buy it...  

Good luck and see ya on the water!

[KenO250explorer]

thanks guys