After dropping the tank to take care of accumulating rust, and taking precautions to mitigate any foreign material from entering the black pipe supply line, there must have been debris that worked it's way to the diaphragm, after re-connecting supply lines.
The fix was to disconnect the bleeder tube connected to the diaphragm and prime the system several times. That process must have "blew out" the particulate that must have entered the system and interrupted the proper gas pressures required. Or, it was coincidental to my issue, in any event, the issue was cleared up and it runs smooth with no backfiring.
Symptoms were; Generator would run, but was starved for LP causing erratic idle and subsequent backfiring.
