Hello looking for help with Ariens Snoblower with Techumseh 7 hp Sno King engine. I'll start off with engine was stored last spring with properly stabilized gas, oil was changed for storage, shaft greased and drive belt adjusted. We just had our first real storm of the season. Engine started fine without difficulty after 10 min of operation engine began surging when not throwing snow. Once load was applied to engine i.e. "snow throwing" problem cleared. After finishing driveway took it into the heated garage. Took carb off motor, the bowl was clean no sign of rust or debris, float, needle valve and seat all in proper order. I drained remaining gas from tank refilled with fresh gas. Re started engine without difficulty, took snow blower back out and problem returned. Any Suggestions? Thank you
Water in the gas, water in the system, varnished up fuel components, would be my guess, but it sounds like you took care of all that. Try cleaning the fuel system with a carb cleaner, especially carb jets.
I have seen a few cases over the years where the little vent hole in the gas cap gets plugged up and the engine surges when not under load. That is probably not it but it seems like you kinda have everything else covered. I would concur with the other response and say take apart the carb and clean it all with carb cleaner and put it together but check that vent hole too.