These are not pressure lamps and they do not have a generator, nor are they pressurised.
Alladin lamps are wick lamps, with a circular wick and a center draught. They burn with a non luminous blue flame rather like a kerosene heater. Light is produced by this flame impinging on a special incandescent mantle.
A poor light can be caused by
1) wick not turned up high enough, it needs careful adjustment.
2) poor quality or clogged wick
3) Very low ambient temperature, self correcting after an hour or so as the lamp warms.
4) poor fuel.
5) very low fuel level.
6) excessive altitude, a special taller chimney is needed if you live at a significant altitude.