Maybe on a regina car, I don't know much about them. However, I can state that a dead pre-pump on it's own should not cause a car to die with less than 1/4 tank of fuel.

The reason is pretty simple. The main pump is plenty strong enough to suck fuel through the system even without the pre-pump, so as long as the integrity of the line THROUGH the pre-pump hasn't been breached it can easily suck the gas on its own.

I guess its possible that when certain pre-pumps fail the mechanism/pump freezes in a certain position that provides even more reseistant to flow, but that seems really unlikely. Its also possible thata really dirty in tank sock would effect the main pumps ability to get gas through the line on its own.

All I know is that I've run a number of 700s down to fumes with dead pre-pumps and never experienced a stall. The main pump whines a little bit louder than normal, but it sucks the gas straight through without a hitch. Only a breach in the line (usually in the hose from the sender nub to the top of teh pre-pump) has caused a stall in any car I've seen.

-rt