Tom what you say makes sense but doesn't actually hold true. Almost without exception better fuel draw occurs when tank is lower than spray bar, Definitly more problems occur when tank high. Guess reason here is tank is pressurized from muffler therefore maintains good flow at all attitudes. Inverted engines of all types often have problems due to tank too high. Tank location in his case is it's far too low for good fuel draw. He could raise tank or use a pump.