If the needle and seat are closed. No fuel will move from the pump. Over time this will over come the check valve in the pump and so not be seen in the filter. I have a clear filter in front of the pump. You can see the fuel slosh up and down as the pump works. I have another just in front of the carb. You can almost see the fuel move in it. Good news, sort of the big junk is stuck in the filter before the pump and the fine stuff is stuck in the filter by the carb. Makes me feel like I am helping things any way. :)

Steve H