Part Number: F8-05070001 (PAF8-05070001)
The part is used for engine models: Parsun F8/F9.8
This plunger moves inside the fuel-pump mounting base to actuate the diaphragm mechanism.
Its stepped end works with the separate plunger spring, which returns it between operating strokes.
It is an internal pump component, separate from the diaphragm assembly.