tgilligan

Hi,

Current tank set up is a single line feed to a mechanical pump without a return. There is an additional vent line that is going to a purge canister mounted just by the tank.

I don't have any issues with vapor lock or fuel pressure but was contemplating about adding a return line for to avoid future issues with vapor lock or any other items that may arise. Additionally, I may consider swapping the carb for an EFI system and while there are some like the MSD Atomic that can be installed on a return-less system, it's recommended to be used with a return line.

To add a return line to my existing setup, please correct me on my current understanding:
* I would need to change my mechanical pump to one with a return.
* Existing tank could be used but would require drilling in a return bung with the appropriate fittings to accept the return line.
* Steel line to be run along the frame rail from the mechanical pump back to the tank.

Assuming the above is correct, here's where I need some education:
* What is the pro/con of converting to an electronic pump? I assume that requires changing the sending unit so would it be easier and more cost effective to simply change the mechanical pump to include the return and then drill the hole in the tank for the plumbing?
* By adding a return line, would I need to add a regulator either with a mechanical pump?

Perhaps I'm just opening a can of worms by looking to do a return when I don't currently have an issue but looking at possibly converting to EFI had me looking at what would be necessary and that was a fairly standard requirement.

Thanks

oldcutlass

Since your car has no fuel issues at the moment and your desire to switch is still a contemplation just wait until your going to change the system. If it ain't broke don't fix it.

tgilligan

Good point. I figured I was poking a sleeping bear but figured I could see what kind of trouble I’d be getting myself into.

coppercutlass

Run a good mechanical fuel pump like a ROBbMC pump. I run one on my 350 and have no issues and i don't run a return. I think many vapor lock issues without returns are from weak pumps.

But on the flip side I did add a return to a 69 impala ss i built a 463 for. Simple enough. Buy the GM fuel filter with the return line built into it then add a 90 degree fitting to the sending unit to return fuel into the tank along with your lines. It does not hurt to have it. There is more pro's than cons.