10-4 if you are running a 12volt system you could be having
battery problems, (low voltage usually will give you black smoke
however) White smoke is indactive of poor ignition the white smoke
is unburnt fuel, I suspect a partially clogged fuel filter is not
allowing a good flow of fuel to the burner, resulting in poor fuel
atomization and incomplete burn of the fuel.
I would check for a dirty fuel filter first.