Hi Wayne,

I have the Fly Models version with a Magnum 120 inverted. I could not use the fuel tank supplied because it interfered with the wing saddle. Not sure if the CMP one is the same. I thought about moving the tank higher in the fuse but was concered about having a problem like you describe. I went with a smaller tank. I think it is a 14 oz Dubro square tank. I have 4 flights on mine and don't have any fuel problems. I am running a 14X7 three blade prop. I took about 3 degrees of downthrust out of the engine mount because it wants to nose over on the takeoff run when you give it throttle. I haven't flow it since I took the downthrust out. Hope that helps!