After reading all the positive reviews, I was excited to receive and use the sprayer.  I took it out to my apple tree, pumped it 10-20 times and went to spray only to find it sprayed for less than 2 seconds-no pressure.  I kept going around the tree with the same results keeping the pumping going more and more.  I read where it might take a drop of oil in the plunger so I tried that with no better results.  I did not over fill the base-it just is not getting any pressure with the pumps.  If any of your have suggestions, I am open.