When my (Raceline) Zetec was on carbs I used a low pressure Facet fast road pump with a pressure regulator set at 3.5 psi. I didn't have a pressure switch just let the pump run continuously, worked faultlessly for years. I now run TB's with the same pump feeding a HP pump & swirl pot, again no pressure switch I just let both pumps run continuously without any problems. Both set ups are that recommended by Raceline.