Rebuilt my series III 109 with a 2.25 petrol engine carb (zenith) used the kit from here. Went o fire up the engine - and it starts (idles fine) for about 30 seconds then dies -when watching the carb, even after the engine dies a good stream of gas keeps pouring into the carb from the main inslet - after 30 seconds or so it trickles to a stop - I have to wait 3o minutes or so until all the extra gas evaporates and then try it again. Then it fires up and repeates the performance. I am completely new to rebuilding carbs, and this is the first one i attempted - what did i do wrong?