My Father-In-Law's single stage snowblower (Engine 12D105-0010-F8) starts on one pull and runs great with very slight choke. Normally, my brother-in-law runs the machine. Last weekend I used it. When engaging the auger the machine will backfire and lose power momentarily. Same thing happens when you start blowing snow. Think this is a carb issue, or something more serious?
If it came into the shop with these symptoms, I would be looking at a lean run condition. I suspect that the float bowl is not filling with the normal amount of fuel. I would be cleaning and rebuilding the carb, replacing the float, float needle and float seat, plus bowl gasket.
Don't do snow blowers here but to add to what Rivets already said
Those symptoms can also indicate water in fuel or a leaking head gasket.
Water will be obvious when you clean the carb
To check for blown gasket, run the engine for 5 minutes then shut down.
Count to 10 then pull the dipstick.
If smoke rises out of the tube then the casket is on it's way out.
Great News - I think it was a combination of dirty carb and old/bad gas. Cleaned things out and it runs like a champ! Thanks to Rivets and bertsmobile1!!
