Fuel return line?

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Mean416

Mean416

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Hey. Converting to EFI, and I was wondering about the fuel return. I noticed on the pass side of the engine bay there appears to be a non connected return of some kind. I'm assuming this is some kind of fuel vapor return line? It's a 1972 model.

Any chance I could use this for a return line for the EFI system?
 
1/4 inch line? Probably vapor return from the fuel filter, I don't think '72s had charcoal cannisters yet (maybe California?). Best bet is check the FSM for your model.
Since you are going to EFI (which EFI, BTW? What engine/body? What does the EFI manufacturer recommend?), are you moving up to a 3/8 supply line? If so, use the factory 5/16 as your return, I wouldn't use the 1/4. JMO.
 
I ran -6an lines for both supply and return on my setup. a restriction in the return could make maintaining consistent pressure an issue
 
D4A5284D-3EB4-411F-96E0-FF0F157FD855.png


Use this and problem is solved
 
Mean416 said:
Hey. Converting to EFI, and I was wondering about the fuel return. I noticed on the pass side of the engine bay there appears to be a non connected return of some kind. I'm assuming this is some kind of fuel vapor return line? It's a 1972 model.

Any chance I could use this for a return line for the EFI system?
Click to expand...
It is not large enough AND THAT LINE IS THE FUEL TANK VENT You can buy aftermarket senders that hae a second port, but it "is known" that aftermarket senders suck for gauge accuracy. If you pull the filler tube you could modify it for a vent and or weld a port in it for the return. or pull the tank and braze a ftting into it. "I thought" there was a thread on here someone installed a return in the stock sender assy.
 
I have a holley super sniper and I used their filter/regulator. With that, I do not need a return line. The filter regulator is mounted above the rear axle and so the return from the regulator is only 2 feet or so.
Holley EFI 12-876 Holley EFI Filter Regulator -8AN

BTW, my pump is in the tank.
 
Seandavid55 said:
Holley OE-Style Fuel Tank Module, 1963-1976 Dodge/Plymouth A Body

How about going this route? Everything in one shot and no return line.
Click to expand...
That'll work for the Holley systems and others that don't require a return line, but many other systems (like the OP's) do require a return, so you still have to plumb one in there somewhere.
Nearly identical to the Holley is the Spectra SP196A1H, a fuel pump/sending unit module that fits in a factory tank and has a return line barb.
 
Professor Fate said:
That'll work for the Holley systems and others that don't require a return line, but many other systems (like the OP's) do require a return, so you still have to plumb one in there somewhere.
Nearly identical to the Holley is the Spectra SP196A1H, a fuel pump/sending unit module that fits in a factory tank and has a return line barb.
Click to expand...

I could be wrong. But I believe the holley systems do require a return line. The module I posted gets around it by having the regulator built into it. I'll have to look into it a bit.
 
Seandavid55 said:
I could be wrong. But I believe the holley systems do require a return line. The module I posted gets around it by having the regulator built into it. I'll have to look into it a bit.
Click to expand...
Holley super sniper requires a return line with a regulator after the efi only if boost is being used. Otherwise what I referenced will work perefectly.
 
I have done 2 cars with the Tanks Inc. fuel pump in the tank and using their tank. The advantage is pump cooled by gas and quiet so I only hear it before engine is started and then only the engine when running. Something to think about if your doing just a cruiser not a race car.
 
Professor Fate said:
1/4 inch line? Probably vapor return from the fuel filter, I don't think '72s had charcoal cannisters yet (maybe California?). Best bet is check the FSM for your model.
Since you are going to EFI (which EFI, BTW? What engine/body? What does the EFI manufacturer recommend?), are you moving up to a 3/8 supply line? If so, use the factory 5/16 as your return, I wouldn't use the 1/4. JMO.
Click to expand...

I have a custom megasquirt setup using a tunnel ram. Very good idea on using the 5/16 for a return thanks!
 
I suppose I should have given a little more info. Maybe a mini build thread in order what do y'all think?
 
The ls regulator includes a return line on it and you can mount it about a foot or 2 from the tank so plumbing is minimal
 
I got a hyperfuel drop in tank with a 340lph pump.
 
Mean416 said:
I have a custom megasquirt setup using a tunnel ram. Very good idea on using the 5/16 for a return thanks!
Click to expand...


FABO rule 49: you can’t say you run a tunnel ram and not post pictures. Seriously. That is a rule. So we will need pictures pronto. Or the mods may remove your post.

























Well, they won’t but you still need to post some pictures.
 
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