Fuel Injection Tank Return Line Location

[75Bronc]

I am currently running FiTech on a modified stock rear tank. I have a walbro in-line pump.

I got my hands on an Aero 23 gallon tank. There is a provision for a return line right next to the fuel feed line. The return line enters the side of the tank and sprays horizontal on the top of the fuel.

Is this an okay place for a return line with FiTech/Walbro inline? Will the fuel get aerated or hot? Would it be better to enter the top of the tank on the opposite side (passenger side), this would separate the feed and return with baffles. Or would it be better to put it on the bottom of the tank?

Don't know if I should put a new return port on the bottom of the tank or on the other side of the baffles or both? What is the best location.

Thanks for the help!

 

[Hazegray]

I don't see why it would not work. I have an old 23 gallon NW tank and I plumbed the return from my FITECH on one of the evap fittings. I assumed that the return line does not have alot of pressure coming back to the tank...

 

[Broncobowsher]

While a lot of us have done the emissions port as a return fitting. Some of us have even put it in the filler neck. While that does get the fuel back in the tank it turns out not to be the best way of doing it.

I've been learning more about this. Turns out the factory engineers do know some stuff. The factory style return lines tend to be plumbed to the bottom of the tank and close to the fuel pickup. This reduces the aeration of the fuel. The fuel mixes rather quickly so cooling isn't an issue. Holley is including this recommendation in the latest instructions with the hydramats now.

I won't say this is the new way of doing it, factory stuff was like this for a long time. But it is the new way in the aftermarket as people learn that the factory engineers actually did know a few things.

 

[turbotim2]

I am running a Sniper and installed return fittings in my stock tanks. The Holley kit came with a plastic tube to install inside the tank to return the fuel at the bottom like others have said. Is there any way you would be able to install a tube like this on the existing fitting?

 

[DirtDonk]

There are probably several ways to do it, although I can't really think of any that would be considered easy.
You can remove the sending unit braze/solder your own version into that area. Or you can figure out some way to insert flexible tubing smaller than the fitting but flared at the outside so it doesn't fall all the way in. Not sure how easy, but it seems feasible.

But in reality having it flow in from the top and just drop on the top of the existing gas isn't a big problem until the tank is almost empty. You probably get almost as many air bubbles in a non-return tank setup just from bouncing around and road vibration as you do from gas getting tossed in from above.
The fuel pickup to the pump is always at the very bottom of the tank and all the air bubbles remain at or very near the top. Even those that go subsurface buoy back up to the top almost instantly where they simply become part of the air above the gas.
I would imagine that in extreme conditions there is some air that emulsifies in the fuel (if that's the proper word?) and could work its way to near the pump. But if I'm not mistaken characteristics of the sock type filter medium is to also separate air from liquid. Up to a point perhaps? I would imagine the emulsified air will get sucked into the filter easily, but air bubbles probably remain on its surface for a certain amount of time.
Anyone know how true that last bit is?

 

[DirtDonk]

This sounds like another great test for go pro!
A nice chance to get some video documentation while driving around with and without return fuel.

 

[Viperwolf1]

The NWMP tank has a drain plug in the front passenger corner that works well for a return.

 

[RonJones]

I'm toying with the idea of converting my BC Broncos early 24 gal tank to the Holley Atomic 2 EFI when it comes available. I've no idea where my tank return line plumbing goes, but assuming the worst, it drains from the top. Moreover, the baffles are oriented fore/aft so they slow side-to-side sloshing but not accel/decel. The Atomic video shows mounting a panel with the inline fuel pump down low in front of the fuel tank to get the inline pump as low as possible so it gravity feeds (see below).

I think a solution for the overhead dribble aeration and sloshing issue would be to use BC Broncos converted remote filter setup with the “to pump” line plumbed low in the filter and mounting the unit low and in a protected location.

https://bcbroncos.com/shop/fuel/fue...or-filter-1-qt-long-version-for-early-bronco/

I have a question about plumbing the aux tank so as to retain same without using a marginally overpressurized 6-port remote valve, but I'll start that in a second post.

 

[Steve83]

Gasoline doesn't aerate like ATF/PSF/engine oil, so it's not a significant concern. Slosh is more significant, and it's not a concern, either. More heat comes from the tailpipe passing near the tank & from the air wash out of the radiator & under the truck to the tank than from the trickle of gas returning.

Just hook it up so all the gas & vapor stay in the fuel system, and it'll be fine. The more-modern you make the vapor system, the better. This ('88-95 style) is the oldest that actually works:

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[jhill52]

Paul is correct in his thinking except it is technically vaporized fuel in the returned gas caused by the pressure drop when gasoline passes thru the pressure regulator .
Fuel can be returned and usually directed toward the pickup in an attempt to keep more fuel around the pickup under low fuel conditions.

 

[75Bronc]

Thank you everyone for your replies. I'm hoping to mock this up in the next few days!

 

[75Bronc]

I ended up drilling a hole in the tank, bending some 3/8 steel tubing and plumbing the return line to the bottom of the tank. I'm pretty happy with the location of the return now.

Thanks much.

 

[SC74]

I ended up drilling a hole in the tank, bending some 3/8 steel tubing and plumbing the return line to the bottom of the tank. I'm pretty happy with the location of the return now.

Thanks much.

I'd like to see a picture. Sounds easy enough. Our you working on a new tank, or a stock tank?
Honestly, I'm scared to weld on my stock tank, even if it is dry and been washed or full of water.

 

[75Bronc]

I took a couple pictures for SC74, but don't know how to post. PM me you phone number or email and I can send them directly. Thanks!

 

[Steve83]

...it is technically vaporized fuel in the returned gas caused by the pressure drop when gasoline passes thru the pressure regulator .

A pressure drop (going from 35psi to 15psi, or 3000psi to 30psi) doesn't cause vaporization. Low pressure causes it, and the pressure in the return line is not below atmospheric pressure, where we all know that gasoline is still liquid. So there is no substantial amount of vaporization happening at the FPR or in the return line.

I took a couple pictures for SC74, but don't know how to post.

www.supermotors.net/forums/thid-5972-how-do-i-post-pictures-sounds-and-or-videos

 

[SC74]

Here are 2 pics that 76Bronc just sent me of how he plumbed the return line.