Fuel problem, please help.

[Blue_Runner]

2004 Yamaha 150 carbed 2 stroke.

Above 4500 RPMs the fuel flow cannnot keep up and primer bulb starts to go soft allowing the motor to cut out. Runs smooth as silk anywhere below that. At 4500 and above someone can squeeze the ball and the motor will not cut out.

Couple things - installed a new primer bulb to be sure it wasn't that. Tank pickup seems to be free flowing and clear of obstruction. Racor F/W separator a little over 1 yr old. In-line filter seems fine, clear from obstruction and trash.

So, what could it be other than the fuel pump? I'm going to go ahead and replace the 2 filters anyway, but don't think it is going to help.