ORIGINAL: TNRabbit
If you have fuel coming out of the carb when you prime the engine, it should start.
I had a heck of a time getting my TT .46 to start before I broke it in. I had to use an electric starter. I'm not sure why you were able to start it with a different tank.
Try blowing thru the vent (exhaust) fuel line on the offending tank to make certain you are getting a positive flow out the carb side fuel line.
When you connected the second tank, was it sitting on top of the fuselage? Was anything else different besides the size of the line?
Sorry so darned many questions, it's just hard to figure these things out without a visual sometimes!
Yeah, I had it sitting on top of the fuse.. Thats why I was thinking the internal tank may not be high enough.. Im going to get new fuel line tomorrow anyways, just as a shot.. The fuel line I got on it right now is too big.. I mean, big enough to worry me that it would come loose during flight.