There is a fuel supply restriction in the carburetor on a Homelite 26ss trimmer. It appears to be in the casting that the primer bulb mounts on There is a rubber flap valve inside the primer bulb that has a small hole under it to allow fuel to come in when the bulb is released but there is some restriction inside that casting or the pressed in metal insert that won't allow fuel to flow in. Instead, air is sucked in from the venturie when bulb is released. The diaphragm is good.