pressure to drop on Carter electr. fuel pump

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Buschi340

Buschi340

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I got a carter fuel pump (Carter #180-P4601HP) from a friend which provides 15 PSI. But I need only max 7 PSI for my Holley 750 carb. Is it possible to drop the pressure with a regulator to the half w/o damaging the pump and is a return line necessary?
 
The thing about a non-bypass regulator is that it forces the pump to cavitate. I'm not familiar with any emissions laws "over there." Can you remove/ modify the carbon canister vent system? If so, you already have a return line "built in," and could use a bypass regulator
 
67Dart273 said:
The thing about a non-bypass regulator is that it forces the pump to cavitate. I'm not familiar with any emissions laws "over there." Can you remove/ modify the carbon canister vent system? If so, you already have a return line "built in," and could use a bypass regulator
Click to expand...

I have no carbon vent system. Emissions laws are not important for this here. This is just a technical question. Can you describe what you mean with "cavitate"? Sucking air?
 
Surely that car had the carbon can originally. Look under the car where the fuel line is near the tank and see if there are some smaller tubes also running front/ rear to the tank.

If you have a regulator with no bypass, the only way it can regulate is to shut off the pump head. This makes the rotor cavitate and bubble up the fuel. IT MAY in this condition add to vapor lock problems. A "bypass" regulator, which of course always feeds "overage" back to the tank, alleviates this condition somewhat and keeps the fuel a little cooler because it is always recirculating
 
No, trust me, there is nothing under my my like this. Only a single fuel line. I restored the car myself back in the days.

My question was can I damage the pump when I regulate the pressure to -50% and is a return line technically necessary for this. I've read the Holley web page but it doesn't comes that clear. They offer both types of regulator and they advises the non return regulator for their HP pumps (14PSI). But on the other hand they offer bypass regulators as well..... Hm....
 
Well you can't damage the Carter pump because it's designed to work against a blind head--when the needle/ seat shuts off.
 
There may be a low-pressure spring that you can fit to the pump. My old holley elec pump came with a 7psi spring and you could change it out to the higher pressure ~14psi spring if you wanted to use a regulator
 
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