The firing order is 1-3-4-2 and clockwise First there are two types of lock off valves
The lock off valve will have either wires or vacuum hose. Usually the lock off is located in lp line from tank to unit before the vaporizer
If it is an electric it will generally be hooked up to the oil pressure switch on side of engine
This is done so if there is a fire and you kill unit the fuel will shut off same with vacuum hose
Usually the hose hooks up at the carb or the intake check these first. Also the carb- mixer
Is vacuum operated,as engine turns over it opens a diaphragm inside if diaphragm is bad you will not get fuel Lp is highly flammable please take every precaution to prevent a fire or injury
Hope this helps
Good luck !