Thanks for the response morwan. I have found that this probably has been caused by confusing the ECU. most of my engines are wren turbines and when you start a wren you put trim to full then throttle to full then immediately to low throttle. I was doing this with the jet cat and i think this was confusing the ECU. Once i paused for a few seconds at full throttle the start up phase worked without a hitch. so far i've had ten or so successful starts and no problem.