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Fuel cell questions.. Return line needed?

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Is it really necessary to run a fuel return line on my L20B with my fuel cell?



I wanna get off my lazy ass and mount my cell today so i can top it off while gas is $2.99, but haven't yet worked out how necessary a fuel return is going to be.

Edited by metalmonkey47
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If your future plans include an EFI engine? You will need a return line. How about an electric fuel pump? Again, a return is a better alternative. There are ways around a return line with a carbed engine but a return is just a smarter way to go, especially, since you don't have the tank mounted yet.

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No carburetor requires a return line. But they are beneficial, and do not hurt performance. There is no reason not to run one.



Datsun added return lines starting around 1970 for two reasons:


1. To prevent potential vapor-lock problems. By keeping fuel circulating through the lines, it doesn't get localized hot spots that vaporize the fuel inside the line and prevent the fuel pump from working


2. To mitigate HC emissions. By lowering the temp of the fuel, less of it will vaporize and escape to the atmosphere



Here's what my Nissan publication says:

Fuel return system

For preventing abnormal fuel temperature rise, the fuel return system has been installed. In this system, fuel from the fuel tank is delivered to both the carburetor and fuel tank.


The fuel return line services to return a part of the fuel to the fuel tank to suit different engine operating requirements, preventing the possibility of fuel heated flowing through the fuel line inside the engine compartment, and elminating "percolation" inside the carburetor.

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Return lines also keep fuel pressure stable if your needle sticks fuel should mostly return back to tank instead of waterfalling out the top of the carb. If ya ever run a electric pump it helps keep them quiet, and they will last longer not running a dead end system. Running a return with a webber down draft normally keeps the pressure in check so ya dont need to use a fuel pressure regulator. Not all pumps are like the factory datsun fuel pumps pressures may vary.

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Yes ... I would .... Since installing your new cell


Especially I f you ever wish to upgrade ...


Your already upgrading ... Might as well prepare a couple steps ahead for .... Ohhhh ... An engine swap :D ... Or possible turbo upgrade as well ... :D


Make sure provisions large enough ...


Good luck

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