I just bought a Hobart champion 16 off of Ebay. It has an Onan engine.

I'm beginning to think I bought a lemon. (I bought the thing to weld with not to work on.)

The engine runs fine but when trying to weld, the arc only lasts about 10 seconds and then it bogs the engine down and the arc dies out.

Any ideas what might be causing this?

How do I find out exactly what model this unit is? Where would I find the data plate so that I can specifically identify it?