I have a 5500 onan in my new fuzion and it's always had a lean pop out the exhaust and would surge when not under a load. I am a diesel tech and refused to buy into the fact these carbs can't be clean...
There is a misconception that the Onan carbs are not serviceable. They can be removed and cleaned out. What you CANNOT do is buy a rebuild kit. But, rebuilding usually, the seals and gaskets are not destroyed. As to the OP's problem, I doubt the reason is the design of a "lean" carb. I have never seen a Gas Onan have surge or popping when under load or NOT under load as long as everything is within specs. Now, drilling out may be a good fix for marginal carbs. Doug
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