An old trick to getting the air out. If you disconnect the return line from the filter and CAREFULLY apply low pressure air to the return line to the tank. You can apply a little pressure to the tank and this will push the fuel up through both filters and if you have a piece of clear hose on the filter return line connection into a container you can see when the air bubbles stop and only fuel is in the system. when you disconnect the air, be careful as fuel may come back up the return line. I have done this many times to avoid using the old style manual primer.
BE CAREFUL and don't just use air line pressure, I saw a guy blow the filler cap off the gas tank once.