Hello Pete; If you are getting blue flame on the start then chances are that you are getting too much gas. Check the start pulse width. You should notice an increase in engine rpm as soon as you see the words FUEL RAMPING. If you don't have a clue as to where you need to be for start, A good procedures to follow is this. Remove the fuel line at the engine - Lower the PRIME PULSE WIDTH to what ever you have your start pulse set at - press the prime button and check to see that you are just starting to get the fuel to flow - Play with the prime pulse instill you find the point at which your system starts to flow fuel - Use that value as your new START PULSE WIDTH - Remember to set you prime back to 150 - During the next start look at the terminal and check for a change in sound as soon as you see the display change to the words fuel ramping - If the change occurs to soon and hot then you need to lower the number - If it takes a while then you need to raise it - You want to hear a change as soon as the display reads FUEL RAMPING. Also make sure that the plug is always pulled out and not touching the combustor inside. Another good practice is to always purge the gas cylinder prior to filling. This cool down the tank and allows a better and more consistent fill. Hope this helps. If the problem continues please let me know. Good luck