[Rick Parker]

There is also a spring on the accelerator pump actuating lever that compresses to prevent damage to the pump diaphram when the throttle is slamed open. it is designed to prevent damage to the diaphram which could possibly burst otherwise. The spring also to some extent controls the flow rate as "IT" limits the force that actually pushes the fuel. At idle there must be a small clearance (.015??) between the pump arm and the lever.
On another note, it would be well advised to seek out the diaphrams intended for alchohol fuel marketed by various companies and use them to replace the standard Black rubber Holly diaphram. Most areas have varying degrees of Alchohol in their gasoline and it will attack the traditional rubber diaphram.