Fuel Return for EFI in a 1974 Opel

The Problem: Tank with no return line, and only 1/4" vent lines.


The Solutions :


1 - Braze/Weld to tank a nipple : Not always easy to do or simple


2 - Edelbrock Fuel Sump - https://amzn.to/3eytYr4 at $340 a decent option. Requires use of a low pressure fuel pump to feed it.


3 - 2 in and 1 out fuel filter - This works BUT you can end up with hot fuel and problems with the fuel pump dying early due to pressure and heat.


4 - An In Tank setup that is available, but in my case wouldn't fit in the tank - https://amzn.to/2R2Evmc


OR


5 - This crazy idea I got from the fact I already had a 3 psi electric pump in the car and a high pressure inline pump that used AN fittings.


In theory it is very similar to #2..
I KNOW the system will work. Its a matter of reliability and how well the High pressure fuel pump handles the positive pressure on the back of it. It should help the pump.. BUT it could cause cavation. Given the inline styles of pumps I don't think that would be an issue.


What do you all think ?


My theory is this..


The Return from regulator is feeding the Feed Tank, so it stays full


The 3 PSI only has to Feed the tank when there is a negative pressure in the tank.. much like it was doing with a carb anyway



The High Pressure pump only had a limited amount of loop to feed so its operating temps should stay low, and being it has pressure to the feed line should keep it running longer.


Also the return to the tank is the highest point of the system so it should self vent to the tank,

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