Could someone explain returnless systems?

[demonpixel]

I put an aftermarket efi system on my 72 pontiac 400 with an external fuel pump; the pump that came with the kit. i drove it today on the highway for about half an hour before i hit unexpected traffic. i slowed the car down and the car bogged and shut off. i am running one vent line from the tank to above the tank to outside air.

i'm starting to hear that returnless systems are not as reliable as return systems, but i know some ls engine cars have returnless systems. has anyone had experience with them? would running a return line make that much of a difference even if i'm properly vented? why make returnless systems at all if they're in fact unreliable? i planned on having my ls1 powered car a returnless system but now i'm not so sure.



my instruction manual says: "This system is the FIRST! of its
kind to control fuel pressure electronically and allow the
use of a single fuel line while maintaining constant fuel
pressure. This system should only be used in applications
under 500hp." OK, so is it changing the voltage of the fuel pump or something??

a buddy of mine said that my external fuel pump on my 72 firebid's system could very well be overheating; that at cruise i should be fine but sitting in traffic some of them are known to overheat. anyone else have this issue? do you recommend any external fuel pumps for daily drivers with an aftermarket efi system?

i know that's a lot of questions but it was totally embarassing pulling over on the side of the road over and over yesterday. if i let the car sit for 15-20 minutes, it started up fine and drove perfectly for about 10 minutes, and then it would just shut off. wait again, drives fine for 10 mins, then dies, wait again, etc.

thanks for any help/advice guys