Raybo- are you an end user or a tech? If you are unsure of how a propane fuel system operates, and what purpose each component does in the system, I suggest you spend the money & call someone who does. It does sound like this system was pieced together which could be why you're having trouble.

Propane is very explosive (about 110 octane), is already in a gaseous state & is just looking for an ignition source. I personally found out that propane can self ignite from a build up static electricity (who knew?). A fuel system is not the place to learn by trial & error- the error could be very costly.

Every time you pull the fuel supply line off the carb (mixer), you take the chance of having propane spray all over the engine (& the ignition system). I know this hasn't happened yet, but the fact is that the fuel system is malfunctioning & this is certainly possible.

I strongly urge you to call a professional in your area to deal with this situation. He should be able to explain what the different components are, what their job is, & generally educate you on the fuel system in a much more safe way then what you are presently doing. I have seen many people get hurt because they underestimate the power of propane.