Originally Posted by ForcesR

More than likely the brass T-fitting connected to the airline that is connected to the airtank is almost completely blocked by flashing left over from the manufacturing process. The T-fitting is acting as a pressure restrictor due to the left over flashing. Take a small drill bit and run it through all three openings of the T-fitting. I have experienced this same issue in the past with the brass T-fittings. I now run a small drill bit through every T-fitting to get rid of any left over flashing before T-fitting installation.