i just built my own 3/8 big line kit for my truck

got it all put on but i was wondering with all the fuel going to the injection pump is there any need to have bigger return lines

 

I wonder the same thing. I think the idea is to get as much fuel & pressure TO the I.P. or potential to get the most fuel without pressure drop. Either the engine will consume the fuel under WOT, or proportionally more fuel will route to the return line under idle condition. But atleast the input side gets what it needs.

 

I am pumping mine with a Airdog 150. Whatever the engine does not use and the return line does not return will go back to the tank at the pressure regulator. Hope this makes sense.

 

i understand but what about stock feul systems

 

No, you do not need to increase the line size. It does not work like a bypass regulator for a gasser. A set amount of fuel is returned regardless of pressure.

Dave