Fuel pump: flow rate vs psi
TECH Enthusiast
Joined: Jan 2012
Posts: 557
Likes: 9
From: Bowling Green KY
Usually you will be about 7psi to your carb iirc? The pressure needs to be low enough that your needle valves connected to your floats can hold closed against the incoming pressure, when the bowls are at the appropriate fuel level. Its been about 15 years since I've worked on a carb. Switched to EFI about 2 decades ago and never looked back. You would need to know the flow rate of that pump, at that pressure, to determine what the pump is capable of. Since carbs operate at such low pressure, the volume capability of the pump should be close to what the free flow number is.
There will be regulator in the system that basically chokes off flow to raise the pressure at the pump. Think of it like blowing through a normal straw. At low pressure you move a certain volume of air. If you were to now blow through a coffee straw you have to blow a lot harder (more pressure) to move the same volume of air. The regulator is the straw in this case determining how much pressure the pump provides.
