The Ultimate Air Trap has been a really great product in that the success rate in the customers hands has been at least 99%. Just as with any new product, we can always learn better ways to help implement its use. Add these tips to the instructions you received with the U.A.T. First start-up with an electric auto-start: Fill the system through the U.A.T.'s third line. Then connect the filling fuel pump to the output tube of the U.A.T. (The tube that goes to the engine fuel pump.) Run fuel through the U.A.T. until no bubbles can be seen in the exit tube. Be sure that the 6mm fuel tubing has a round, not oval cross section. Use a rotary on/off valve between the U.A.T. and the fuel pump. During the first engine run set the throttle to about one-half power and shake the model observing that no bubbles exit the U.A.T. This may require a few minutes of running until the sack in the U.A.T. is completely air free.