Works as Norm said A couple pics to show the fuel flow when you push the primer, the fuel goes up the lower hole at the bottom of the primer cap and into the centre brass main jet.
I never had much of a problem with the original primer caps and plastic needles but the plastic needles would stick sometimes and I'd have to push the primer about 20 times then it would start ,that was mainly when the mower hadn't been started for a long time probably the fuel had evaporated and left the oil behind marking the needle stick, the needle with the Viton tip is heavier and I only need to prime 3 times.
