A friend with a newly aquired old six cyl flat head propane forklift had the problem of idle only with choke completely on, if he tried to give it any throttle it would instantly kill. After a frustrating week of cleaning and trial and error testing got him nowhere I did some diagnostic tests for him. I've read that the regulater reduces the propane pressure to 6 psi. His was only 2psi, so I took a pressure regulater that was adjustable from possibly an air compressor and put it in. I slowly cranked up the pressure to 6psi and it ran perfectly. He wants to continue using the air pressure regulater because it is adjustable and it solved his problem. What could happen if he continued to use a regulater designed for air pressure? Cosmeticly the apperance of the two regulaters are waaaaay different!