White smoke can also be from an improperly timed injection pump. I had my injection pump overhauled and I reinstalled it to the scribe marks I made before removing it. My Westerbeast 50 started right up but was smoking on start up and would not go away. Mechanic said the timing was off so we adjusted the pump, started the engine, observed the discharge, shut it down and repeated until we found the new position for the injection pump. It was not much of a rotation of the pump but the difficulty was working against the injection lines. And right this second, I can not remember if we advanced or retarded the pump.