[Paul W]

If you have carbs, they don't actively need fuel when the engine is greater than 5,500 RPM....that's what the bowl on a carb is for. It fills when required, and is the fuel reservoir. Then once it goes down in level, the needle valve opens up and refills the bowl.

I would say there is something wrong with the set up. If it was working with your old system, then it is most certainly something with the new carb setup.

 

[Paul W]

I would say it's something to do with the jetting of the carbs.....but it's been a long time since I've worked on carbs.....

As far as the fuel pump goes, I'll wait for others to chime in.