Adding Fuel Return line to 1970 Mopar

-
J

josekh7

Well-Known Member
Joined
Apr 26, 2013
Messages
95
Reaction score
2
Location
los angeles
Hey guys i am upgrading my pump to an electric pump and i need to install a return line how do i even go about this. I do have the old gas tanks with 4 venting hoses to a cylinder type thing.
 
That's for vapor, I think you will want to order a sending unit with the extra nipple and then fab a return line maybe using the 6 pack fuel filter with the extra nipple. So the fuel is constantly looping from the tank to pump to filter and then from the filter back to the tank via the sending unit extra nipple. May want to look into the oriface size on the filter since it was designed for a mechanical pump. I could be completely wrong though.
 
You can drill and add a nipple to your existing sending unit also if you wanted, or even to the filler neck if need be.
 
There's a few ways to skin this cat. If I had one of these cars, I'd convert it to the 69/ earlier open vent looks like this:

2cmugso.jpg


If you are just building an anti - boil return, IE with Wix filter and built in return

http://www.partsgeek.com/assets/rep/full/1114558.jpg

You actually COULD use the factory vent.

Another way is to leave the factory system alone, leave the front tube open (which will BE the vent) and make sure it's high enough it won't siphon over

then do like I did for a return..........empty the tank, and fill it with CO2 from a MIG tank. Punch a hole in the front face of the tank away from the sender, and silver braze a fitting / tube into the tank
 
can i just punch a hole in the corner of the tank install a fitting and fabriate a return line? im just scare there will be venting issues since the return line will bring the fuel back with pressure 6-8 psi.
 
67dart i think you are on to something just break it down a bit more... too many solutions and i only have one brain lol
 
josekh7 said:
can i just punch a hole in the corner of the tank install a fitting and fabriate a return line? im just scare there will be venting issues since the return line will bring the fuel back with pressure 6-8 psi.
Click to expand...

The fuel will be going out of the tank at the same rate (almost) that is going in via the return minus what the engine uses, so no pressure building (vacuum maybe, if the tank isn't at least cap vented)

Think about it like this.
There is less fuel coming back to the tank than went out, because the engine used some before it came back. :)
 
i currently have my purge line set up in that manner , i beleive its connected to the vapor canister in the trunk
 
Newer fuel gauges/pickups have an option for a return as well as 3/8 and 1/2 lines.
 
josekh7 said:
can i just punch a hole in the corner of the tank install a fitting and fabriate a return line? im just scare there will be venting issues since the return line will bring the fuel back with pressure 6-8 psi.
Click to expand...

I added a return on my 67, which of course never had one. As above^^ I drained the tank, and plumbed the MIG bottle to the feedline. (I use pure CO2) "backfill" the tank with CO2 at low pressure. Then get up in there next to the sender. Take a sharp "awl" and punch a hole, after first cleaning it well. the punch (not drill) will avoid chips, and will leave a rolled lip, making it easier to silver braze. We used to call this "silver solder" but the proper name is "silver braze."

If you are concerned about fuel aereation in the return, either do install it low in the tank, or just use a longer tube and stick it 'down' into the tank towards the bottom.

You can use about anything your skill level requires. One mistake I made was to use too small tubing, which ----later when I went EFI-- kinda bit me back. So I would us a 3/8 piece of tube, or even a brass or steel no6 fitting.

The sender you posted will work, too, but as mentioned above, "repop" senders have a horrid track record for calibration issues
 
17 gallon RCI fuel cell. Holley bypass reg. feeding 340 six pack. Holley black pump. 3/8 line to reg 3/8 line back to fuel cell. 3/8 line for fuel cell vent.
 
You must log in or register to reply here.
-

Back
Top