I cannot believe this thread. LP will not gasify when cold. That's why it won't start. LP forklifts should never be stored in the cold.... Sell forklift and get a diesel forklift with glow plugs.
Propane has to be extremely cold to not evaporate. Like well, well below the freezing point of antifreeze. And propane "carburetors" are just negative pressure regulators so hardly any pressure needs to be maintained in the tank to feed liquid into the evaporator.
Forklifts are hard to start in the cold because they never get any maintenance or care. Especially not the ones stored outside.
And why go diesel for cold? Gasoline engines start perfectly fine in freezing weather with no glow plugs. The only engines I've ever had problems with due to the cold are diesel.
EDIT: propane generators often have problems in the cold. This is because they rely on higher pressures to feed their much cheaper fuel systems, and because they draw gas from the tank, so the propane gets colder and the vapor pressure gets lower and eventually it can't sustain the pressure that the generator wants to see.