The Lp is a liquid , the vaporizer takes the liquid and hot water from engine flows through vaporizer turning it to vapor which then goes into mixer (carb ) if the thermostat is not opening properly it will cause the water from the radiator to the engine to not heat up which in turn doesn't change liquid to a vapor which in turn causes too much fuel to enter carb
Resulting in a too rich environment and causes engine to die or falter if you let it run a minute the vaporizer should be warm to touch and after a few minutes it will be hot enough to burn you that is a sign that it is getting flow from engine to vaporizer