I had issues starting up a power unit on a pivot yesterday that has a 1 year old murphy pressure controlled throttle system.  After starting it up and having the power unit shut down several times I realized that the pressure needle on the throttle system was not returning to zero, but instead only went down to 30 psi.  I finally opened it up and adjusted it so that when everything was disconnected it was a zero PSI and the everything worked.  Has anybody had this happen?  I wonder if since I left it between the upper and lower limit pegs for winter if the heat and cold caused the pressure needle to reposition itself over winter.