QUOTE(Superhawk996 @ Dec 7 2022, 01:32 PM)
Generally speaking, it is bad practice to use a high pressure fuel pump intended for fuel injection to feed carbs.
Makes no sense to use a pump capable of 30 psi to feed 3 psi to carbs.
Pumping fuel up to high pressure and then regulating it down just adds extra heat to the fuel. There is a reason Porsche used a different low pressure fuel pump for the /6 carb equipped cars.
Then there is an added failure mode with a high pressure FI fuel pump. If the pressure regulator fails, you'll have high pressure fuel at the carbs which will completely overwhelm the float and flood the carb fuel bowls. Far better to have a low pressure (~5 psi pump) that is regulated to 3 psi. Then if the regulator fails, car will still run (but poorly).
Sorry, not trying to argue, but I think it is important for others to understand the system.
Paragraph 1 and 2, no comment.
Paragraph 3: The pump does not produce high pressure, it only produces what it needs based on the pressure drop of the system. If there is no pressure drop, as in the pump is open ended, there will be next to zero pressure in the system. As you adjust the regulator, it imposes a restriction on the return side that increases the fuel pressure. You add just enough pressure drop for your desired psi.
Paragraph 4: PMO regulator is a mechanical regulator with a bolt that adds pressure drop to the system. It will not fail.
So in the diagram below, crank down on the regulator until pressure is set where you want it at the carbs. If the regulator is wide open, there will be very little overall pressure in the system. As you start cranking the regulator closed, it will increase the system pressure BEFORE the regulator.
The old school pressure regulators are crap and add the restriction before the carbs. For that type of regulator I completely agree with all your statements above.
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