Did the owner's manual say to prime it? I've had gas (Onan Marquis Gold 7000) and diesel (Onan Quiet Diesel 7500) gensets and in both cases I just hit the starter and they cranked right up. None of my owner's manuals ever said anything about priming them even after not running them for a month.
I ALWAYS put Sta-Bil in the gasser so the fuel wouldn't go bad during periods of non-use, and even after a month it would only take an extra couple of seconds of cranking for the engine to start up.
2006 Fleetwood Excursion 39L
Spartan & 350 CAT