RE: Dubros round nose tank has less useable fuel
I also dont like those round nose tanks, and never use them. However in your case that cannot be the reason for dead-stick.
When you apply throttle, even for a split second the fuel in the tank will move backwards because of acceleration, and stay there.
you dead-stick happed either because of bad plumbing, air-leak, ignition failure, opto kill fail, bad plug, mis-tuning or bad fuel.
pick one.