Rick,
my first question would be what type of LP system do you have the original system had a regulator that bolted in place of the thermostat housing. They provided pressurized fuel to the carburator. Some were preset and others were adjustable. I THINK that it should be around 5-9 PSI. The most common problem I use to see with this system was that the carburator fuel needed to be set. There should be a short linkage on the side of the carb. Made of aluminum. Hold the center with vice grips and loosen the jam nut on each end a few turns. One end is left handed thread. Start the machine and allow to idle. Shorten or lengthen the rod by turning with your finger and thumb until it "sweetens up". Snug the jam nuts gently and you are finished.
If it is an Impco style fuel system post it to let us know and we can address that style.
Steve