I have an onan engine on my tractor. The engine surges from idle to wide open throttle. The voltage regulator went out and I think voltage spikes from surging caused it? I changed the plugs and wires and condenser,checked for vacuum or air leaksand found none.
I had the same problem. Clean carb. Mine had a lot of junk in it from over the years. Pull air cleaner assembly and top plate of carb. Pull out float and needle. You'll have decent access to bowl. I used q-tip and Gummout. Flush fuel & install new filter. I havn't had a problem since.
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