Fuel Injection vs. Webers, what's the difference in plumbing/hardware between the 2 Options

[Type 47]

OK, i get carbs only need one fuel line, but hey, there are 2 sticking out of the bottom of the tank.

I Did the Tangerine SS lines to eventually go back to FI, but going with the Webers to get the thing up and running.

Out of the tunnel and into engine bay, what's going on with the orphan fuel line? Block it off out of the tank or in the engine bay? Which one gets blocked off? The one with the tank screen filter or the other?

And What the Hell is this little white tube? Is it for the FI or does it have some function with the carbs? I don't think so but I keep seeing this tube in my disassembly pics.

[Superhawk996]

@bk911

I agree with your assessment. I was largely thinking of the old school regulators that go before the carb. I wasn’t looking at or thinking of the flow diagram for the PMO regulator. Thanks for sharing that and keeping me honest!

Since the fuel pump is a positive displacement pump, there is still some nuance but as long as the fuel return loop is not adding significant flow restriction, the pump wouldn’t be adding much heat gain to the fuel. I see your point.

To use an extreme example, if the pump was large as to be delivering 100 gallon/min flow, and you were trying to force all that flow that through 1/4” tube, you would end up with a significant pressure rise in the discharge tube, significant heat gain of the fluid, and poor pumping efficiency. I.e - it would be like a water brake dyno. (IMG:style_emoticons/default/happy11.gif) I know this is extreme and isn’t what you are proposing but speaks to the general idea of not using a pump displacing more volume than needed to achieve the desired operating pressure.