Thanks for the advice. I methodically went through every connection, vent, etc., only to find out that the Y-valve was set to go to the overboard discharge. The previous owner had removed and discarded the handle, telling me it was set for tank discharge. I bypassed the Y-valve with a 45-degree PVC coupling from Home Depot. However, it seems that the discharge should really go through the vented loop before going to the tank. Any thoughts?
