Is it white smoke? If so, that's unburnt fuel. Check the spark plug for fouling/damage and make sure the transformer is firing it. With it out and the wire connected, lay it against the housing as far away from the fuel as the wire will let you. DO NOT TOUCH IT AS YOU TRY TO START IT. Make sure you have a good, bright blue spark. If the plug is good and there is no spark, you probably need a new transformer. Be ready to unplug it just in case while testing it, don't count on getting to the switch.