I would check your pressure coming out of the vaporizor,on top of it should be a 17mm hex,take this out and put a pressure gauge in and see what it is,should be 4.5 PSI ,did you replace or rebuild the regulator? Pressure might just need adjusted.

roc109,
This probably means that the LPG fuel pressure sensor haas shorted out or that an abnormal rise in the fuel pressurein the fuel pipe from the lpg vapo to to the injector continuse for any length of time. Remove the fuel pipe from the injector turn the ignition switch to on you should hear a quick hiss and it should fall away to nothing if ok.

Regards Titus