F115 starving for fuel

[yamaha808]

I just repowered with a F115. Recently after 30 hours, the motor idles fine but after a while of operation the engine seem to be starving for fuel at rpms over 2500 rpm and it starts to bog down. I back down the trottle and it idles fine. I checked the bulb in my fuel line and it seems empty or on the verge of collapse. Is the problem with my fuel lines? Do i need a fuel bulb? is the problem with my motor? Any useful suggestions is greatly appreciated.

Aloha
James

[yamaha808]

This is the second bulb....the first would be sucked flat. this one is on the verge of being flat. when we try to pump it while it is starving, it doesn't recover. we had to disconnect it and it will pump fuel through the bulb. then reconnect and we could pump fuel to motor.