I am having some issues getting my VQ models AT6 up and running. I have a magnum XLS46A installed sideways with a Jtec pitts muffler. I have tried several different new glow plugs. Here is what's happening. The engine starts fine and seems to run okay. I have run about 3 tanks through it and have leaned it out. . Well, I took the plane to the field the other day and for some reason it starts running goofy. When I hold the plane up in the air to do a run-up. It immediately dies as soon as the plane is held upright. It runs fine on the ground in the horizontal position, but as soon as I hold it up in the air it dies. I would assume this is a fuel problem. I checked and my clunk is not stuck. The fuel lines appear to not have any leaks. The tank itself seems sealed without leaks. I also checked and all my lines are correctly identified. So what gives?
At this point, I have pulled the tank out and I may replace with a better, great planes tank. I hate to do all this though, if its something else causing the problems.