Hi gray, this is a perennial problem because they don't all work the same way. You might try reading this description, from a different Ryobi model but alleged to be typical:
http://www.fixya.com/support/t3064580-gas_lines_fell_apart_new_onesSome systems pressurise the carburetor, some bleed air out of the carburetor, and some pressurise the fuel tank. The description above is for a 3-line primer, like yours, and may work. It sounds a lot different from the connections you seem to have at present.
