I found a flaw with my pump. It has a hose which I screw onto the valve stem. Nowadays, some brand new tubes have valve cores which are not screwed in tightly.
I had a similar problem a while back. I use continental freeride tubes on my touring bicycle. They have the removable Presta valve cores. I tightened all of them up with a valve core tool. I have noticed that lazine and some other mini pumps Including the Stompump which I am going to purchase have the screw on chuck for the presta valves. There are a couple of companies that make different chucks that may be compatible with these pumps. I am going to see if I can get the Jaco lightning presta chuck to work. It slips on than you depress a button at the top to