I have found with ours, if the can is on the ground and I'm pumping up high, it tends to leak.
I put the can up high now and run the pump.
The pump I'm using is probably 5 years old and used for gas and diesel both so that could be part of the problem also.
I actually keep my fuel cans on one of those plastic shelves that sits about 14-16" above the floor, and I can pull my mower right up to it so that sounds like it'll work out perfectly to just leave the can where it sits and refuel that way. (picture from a couple of years ago when I was in the middle or rearranging things. It's much less cluttered now and the owl has been evicted)