Use an on/off valve in the line between the nozzles and the pump, close it when pumping the oil into the tank, then open it when ready to fly or smoke , if you burn all of your smoke fluid when flying you most likely run the pump dry, next time that you refuel ( oil ) open the valve then pump the oil slowly to re-prime the pump then close the valve and continue filling the oil tank. If you happened to forget to close the valve during refueling ( oil ) make sure that you drain all the oil from the engine and pipe ( very important ) or you could have during start, a) a fire, b) a big bang from the excess amount of oil been burn, this could ruin your pipe.

I test my smoke right after starting the engine with half throttle, no less. It happened to me once, after TO. I try to do some smoke but nothing happened ( dry pump ).

That's all I have for now.