Why is this pump for a bronco with electric wipers? Why does the wipers effect the fuel pump? Thanks

Before electric wipers in the Bronco, the wipers were vacuum operated. The vacuum for the wipers was provided by the fuel pump. The fuel pump served two functions. If you have an early Bronco with vacuum wipers, this fuel pump will not provide vacuum for the wipers to function. We do not have the combo fuel/vacuum wiper pumps available.