Was wondering if anyone can help me. I have a topflite p51d arf with a os 75 ax engine. I have had nothing but problems getting this thing to run. Ive been doing alot of research and the inverted engine location is i guess tricky. The engine keep hydro locking. When I do finally get it running engine keeps stalling out on me. I tried leaning out the low end, and put in a hotter plug. It made it better but am not confident in the engine. Ive only flew it twice since I finished building it and today it dead sticked on me and although i landed it, it landed hard and killed my retracts and the supports in the wing. Is it because of the tank location? I got fed up and ordered a os fs110a pumped engine. Will this engine because of the pump solve these issues? And is there any other pointers?