Technical New Return Line into Fuel Tank

I built the gas tank for my '26 Ford T coupe from 16-gauge steel. It is 12" tall x 7" wide x 40" long. It sits across the car in the trunk on the 7" side, right up against the bulkhead I built between the trunk area and the cabin area. It has a very short filler neck, a roll over vent (1/4" pipe), and about a 2" hole for the fuel gauge in the top of the tank. The fuel outlet is in the bottom of the tank.
The problem is I need to add a return line for a new fuel system, so I need to make a hole in the tank in the top, which is pretty accessible.
Of course! It's full of gas!
Having to remove the tank would be enough to make me abandon the project. I would have to remove that interior/ trunk bulkhead. Of course, both the trunk and the interior side of the interior work (most is glued in) would have to be removed to even access that panel. I really didn't build it with the idea of ever removing that tank, but you know us hotrodders never can leave well enough alone.
Anyway, short of draining the gas and filling it with water, are there any alternatives?

I'm not even sure of what kind of a fitting would be used. The biggest hole into the interior is through the gas cap. Not sure how I would ever get a fitting or a nut in there and in place. If I made the return line inlet very close to the filler neck. I might be able to Houdini sumthin' in there, maybe! I don't like the idea of welding a bung in there unless I really have to. The tank is nicely powder coated. Never welded on a used fuel tank. Would I be OK if it is full of water to TIG in a bung? Man! It just seems so foreign to stick a water hose in the fuel tank! I built that tank with bright shiny sheet metal and coated it immediately with some tank coating. All I remember is it was blue. It has worked well. The welding would kill that in the heat zone. That would need somehow repaired.
It would be so much easier if there was some way to install a fitting with one side only access.
You guys know of anything?

I just don't like the idea of filling the tank with water, but unless I'm missing something, it looks like the only alternative.

 

Fuel filter with return line

 

https://teamcpp.com/2022/02/cpps-ez-return-rivet-fitting-is-a-universal-solution/

no weld tank fitting

https://www.speedwaymotors.com/CPP-...Return-Fitting-1-4-In-NPT-To-6-AN,487789.html

 

Take out the fuel tank sending unit and weld a tube onto it.

 

You should factor into your plan that the return should have a long tube to discharge the returned fuel somewhere near to the bottom of the tank. Apparently, allowing the returned fuel to simply fall from an orifice at the top of the tank creates static, with potentially catastrophic effects.

Chris

 

Thanks Anthony! I believe that will work.

I hadn't thought about that. Is it really a thing? A gas tank would be a bad place for a static spark! But let me ask a question! What if I tee'd the fuel line right below the tank and put the return line into the new Tee?

 

I did this on mine back in 2012. Return line into the FILLER neck. And I don't see why teeing into the fuel line would not work. As long as the tee is between the tank and the pump.

Ben

 

If there is room on the sending unit, remove it and drill a hole in the top of the sending unit and insert a tube that goes within an inch or two of the bottom of the tank, and solder it to the sending unit. Copper tube works great and is easy to solder. Put a 90 degree bend in it facing where it needs to go before you solder it in place. Easy and safe. I have done this and it works great.

 

A 'thing' or an urban myth? I dunno as I'm not an expert, but if you Google fuel pickup and return and examine the pics it's hard to find one that doesn't return down to somewhere deep in the tank. Aftermark and oem too.

One could argue that fuel falls in from the filler when gassing up, but that might be earthed by the fuel delivery nozzle, and it's only happening when refueling, and not almost constantly as it would be when the engine is running. I think every tank I have has the longer return, where there's a return.

Chris

 

I can't use the filler neck. It's too close to the tank. So, I guess you didn't run a tube to the bottom of the tank to avoid static, and you have not blown anything up yet?
I think the Tee idea might work, too. I don't know how much pressure there would be in that return line. It would have to work against the head pressure of the fuel in the tank, wouldn't it? If I ran a tube all the way from a top inlet to the bottom of the tank, it would have to work against almost the same head pressure, I think.
The Tee at the bottom of the tank would sure be the easiest solution. The tank has a 3/8" NPT female bung for the outlet. It would be easy to plumb a T and return line right in there.
Anybody have any thoughts on whether the Tee'd in return line is a good or bad idea?

 

All the in tank fuel pumps for FI that I have seen, the return line is plumed into the top and the fuel just falls into the tank. No long tube.

 

That would work. I wouldn't have to disturb the tank in any way. Wouldn't even have to drain it.

 

Can you just get a fuel sender for the tank with the additional line on it for the return? Thinking of something like this.

 

Good answer.