Onan 5.5K Generator

Having trouble getting my generator to run. I dove into it yesterday and found that apparently it's not getting enough fuel through to the carb. Disconnected the fuel line, removed the fuel filter...it's open, evidenced by being able to blow through it. Some gasoline blew out of it and some runs out of the feed line, but not what I would think would be an adequate amount. The unit acts like it wants to catch and start running on its own, but it quickly stops when I let off the starter switch. I removed the spark plug, grounded it and hit the starter...good spark, so that's not the problem. I removed the breather and injected a small amount of gasoline directly into the carb and for a few seconds, it runs. Which tells me I have air and spark, but not enough fuel.

So....before I tear into the carb to check for a stuck needle or float, is there a separate fuel pump for the unit or is it simply a vacuum feed? I do not have documentation on it that came with the coach, and can't seem to find any documentation specific to my unit online.