300/440/550 Uh-Oh I need help. BIG time.

[Serio]

Ok well I posted in the general forum awhile ago about my 550's starting problem. Well I cleaned the carb (probably the first owner to do so, it was FULL of crap); however, I believed the problem is my fuel pump. Today I checked the crankcase pressure, (correct me if I'm wrong but it appears that these engines use a vacuum pressure fuel pump run off the crankcase) and my worst fear came true: zero crankcase pressure. If I pull the line off my carb (no cracks/leaks in the line) I can blow air unrestricted. What does this mean? What should I check first? Or am I just freaking out about something I have no idea about?

Thanks,
Serio

 

[N2 H2O]

see if air comes out while the motor is turning over

 

[Matt_E]

If it's a piston port motor, you won't be able to get much, if any crank case compression.

 

[Serio]

OK! I Think it's just a breather tube, or an emissions thing; because, no air comes out when it turns over, and it runs perfectly so I'm just going to eave it. Went out yesterday and had an awesome time. Thanks for your help guys, I guess it was a false alarm on my end! I'm still learning...

Thanks,
Seerio