When I ran my FS91SII in the house, the entire house filled up with smoke. It was set for rich so that was inevitable even though it was at idle.

When I run any other engine in the house, I always pump off all excess fuel in the tank that can be pumped out. Its only to burn off excess fuel in the carb and any that I can remove from the tank just like OS recommends. It usually runs for just a few seconds. Otherwise, if I have just setup a new throttle setting or installed a cowl then I run the engine indoors. It is always a test and only at idle and only for under a minute. It beats carrying all the tools to the field or missing a day's flying or crashing because you didnt setup something correctly. My house has large french windows in all directions and the room is just 180sq.ft

Not defending my actions here, just telling why it is necessary sometimes. Anyway, we are digressing from the main issue here

Ameyam