No Crankcase Pressure

[FLY N FISH]

Hi all, I have a 2005 250 EFI. Noticed my onboard oil tank was not staying full. So after troubleshooting everything. I disconnected all lines Connected to onboard oil tank blew them out with compressed air. Went to the check valve, started the engine not pulsing air pressure out of the check valve, replaced the check valve still no pressure. I put a pressure gauge on the barb fitting of both check valve zero pressure. Any idea what is causing this?

 

[w2much]

Did you also blow air through the check valve fitting on the motor. It may have gunked up inside. Or you may have a crack or air leak in the line. Do a pressure and vacuum test.

 

[FLY N FISH]

Yes, I replaced the reeds today, and when I had the intake off I blew it out. Got everything back together started the motor had the pressure gauge on the check valve...NO PRESSURE. took the gauge tube off, put my finger up to the check valve, NO PULSE.

 

[Faztbullet]

Checked compression on that cylinder??? If you have no pressure that cylinder wont run...

 

[Steve@granbury]

I have a very similar problem on a merc 300x. On board oil tank does not pressurize. So I took a ballon, attached it to the air pressure line and nothing, no air, actually a vacuum. Slight pluse when the engine is running but no pressure. I can blow on the air pressure line and oil flows perfectly from the oil tank to my motor reserve tank. Can the engine oil check valve stop pressurization?
Any help will be appreciated, thx