Interested in opinions on this -- am I thinking the problem right?

Have a 90 GL which had a whiney fuel pump. Went to pull it apart this morning and when I disconnected the tank side of the pump didn't get the flow of fuel I'd expect -- even after opening the gas cap. Fuel color is clear with no bits. If the line from the tank is horizonal, I get nothing. If the line is pushed vertical I get a slow stream (about 1/4 the diameter of the line). As a test, I pumped air backwards through the line into the tank (and could hear the bubbles in the tank), but no change at all.

Am I thinking about this wrong? Shouldn't I get a solid flow from that line? Suspicion would be an obstruction in the tank...

If anyone can email me or call (757-621-6230) about this, I'd like to know before I put it back together.

john