Fuel line as a "reservoir"

[Dragon Slayer]

Looks like a nice 5 valve pump. can't believe that isn't providing you plenty of fuel, unless one of the inlet check valves is leaking and the pump stroke pushes some fuel back to the suction side.

 

[INTMD8]

I've never seen that pump but I think it looks nice! Looks like they have check valve area covered.

As a test maybe you could temporarily mount a small fuel cell somewhere and feed the pump with a bigger line.

 

[Ceedawg]

Take line loose from carb and stick it in a jug. Start engine. Then you can see how much fuel the pump is pumping into the jug. Make sure bowls are full first, engine should run for at least 30 seconds before needing the extra dribble from a container.