EFI return line, use emissions return?

Dart,

Not quite sure I get you right, but to claridy, I don't have any Vacuum in my tank at this time, the open cannister return line allone will see to that. I allso think my filler cap is vented judging from the smell in that area on hot days! :)

Its a long time ago, but when I replaced the stock mechanical pump, I did go for a high capacity unit that would correspond to my expected horsepower output, so as with a carb, it can't really see why it wouldnt bring the correct volume of fuel to the electric pump like it would bring the correct volume of fuel to a carb.

Granted, as the return fuel now feeds back downstream of the mechanical pump, this limits the demand on volume, if adding a proper return line reveals mechanical pump capacity to be an issue, I'll see the O2 values leaning out on high load and install an electric low-pressure pump near the tank.

At the end of the day, I am convinced the issue is fuel circulating in a loop in a hot engine compartment with no return line to facilitate circulation of cool fuel or path of escape for vapour. Granted, a fuel line passing by the engine block does not improve matters, but I think the effect is relatively small.

Annyway, Thanks a lot for all high-quality information and comments provided! My options are certainly clearer now, just cant wait to do some wrenching during easter! (car comming outr of winter hibernation tomorrow! )