I like Jon's idea. Thanks for pointing out that port on the filter base. If you find yourself without prime after running out of fuel and without a garden sprayer, try removing the secondary filter, filling the filter cartridge to the brim with fuel, replace and start. On the two occasions I ran out (don't ask) this was sufficient to fire a couple of cylinders, which spins the engine enough to get a good suck going. After a few seconds of coughing and sputtering we were good to go. Not sure it always works, but worth a try if you are stranded.