First, for clarity sake, please don't edit former posts with new info, it confuses the issue. ( trying to help keep it simple)
How is/are you tank(s) mounted ? you do know they have to be in a certain position to draw liquid to the regulator, correct ? -My tanks are mounted horizontal with metal forklift tank mounts. I made sure the pin is in the correct position. There seems to be no problem getting liquid fuel to the vaporizer.
This could be part of the issue if you are only drawing vapor from the tank.
the tank is FULL right ? All fittings tight and sealed, no double gasket on the tank to hose connection ? - The tanks were filled and never touched again till now. I have 4 full tanks as of right now. No leaks detected and no double gaskets.
You are using lift truck tanks and not LP cyls for a grill right ? - I am using 8 gallon (33.3 lbs) tanks from forklifts. One even has a sticker on it of a forklift.
Not trying to be an ass, I run into this stuff everyday ( yesterday I drove 45 miles to tell a customer his fuel tank was EMPTY, and charged him labor and mileage! He was not happy, and I don't work for free ) - You ought to.
I run into tanks not positioned correctly, IF the truck runs at all, it runs poorly, and again they get mad ( it's not my fault, there is a reason there is a PIN that fits into ONE spot in the tank ! ) - The pin is in the hole and as far as I know is correct. At least that was the way it was shown to me by someone who runs propane on their rig.
the regulator, is it new or used ? any possibility it could have a leaking diaphragm ? rebuild kits are fairly cheap, and not to tough to do. a used regulator may have a build up of "propalyne" a tar like substance that is present in the gas and leaves a deposit in the regulator, causing parts to stick and clog.