what Scotty said
Giving the carb some love and attention is the most important part of the above advice... a spark plug and filter are good, too.
I fight this stuff with my generators and little 50cc pit bike every year, it's real pain in the neck. Fortunately it's not uncommon, any Honda or Yamaha, lawn and chainsaw shop can clean up the carb for you (or if you're like me, just do it yourself) to get it running. From your post, sounds like you will be taking it in. The key with that is to know what to ask for, so you don't get, ahem, taken in
From my experience, generators and small gas engines typically don't need new gaskets or parts replaced like your typical carb 'rebuild', not even a 'tune up'. just an internal carb cleaning, unplugging of the idle jet (often the culprit), maybe the main jet (sometimes the culprit). the jets and float bowl get gummed up with residual gunk, that blocks the small amount of fuel the carb rations out to the engine (the gunk is just the heavier chemicals left behind, after the lighter ones have evaporated).
Today's gasoline seems to have been engineered to go bad in as little as a few months, when stored in small quantities (like the float bowl of your small generator). I've been using this stuff called "Stabil" fuel stabilizer additive, which helps, if your small engine runs from it's own dedicated small fuel tank.
One trick that sometimes works, is to block off the incoming air at the air filter horn, and hit the electric starter for 30seconds. The high vacuum will sometime dislodge gunk from a plugged jet. Seems to work about 20% or the time for me, but it's often easy, if you can remove the covers and the air filter, plug the carb intake with the plam of your hand, not always possible with every generator.
I'm no small engine mechanic, but I do ok with the larger ones as a hobby
Originally Posted by SuperG
Great, thanks. Yes, everything I've ever read says run it pretty regularly if you want it to continue running regularly. Unfortunately that doesn't seem like it ever occurred. So, leaving out the "carb rebuild" it sounds like new spark plug and new fuel filter...any other advice? I figure the key to getting it running is to "get it running". A couple hours of idling could do it wonders.
I figure the thing isn't much more sophisticated than a lawnmower which I've coaxed to life after 4-5 years of not running (with old gas in it). That basically involved gas right in the carb. Done the same with an old scooter. The location of this thing under the van makes it a real bitch to get to and fiddle with though.