Copper Fuel Line?

Previous owner ran a copper line from tank to fuel pump. I didn't think much about it. There was no tank so I got a clean used one, thought I cleaned it well, attached the tank and started the old beast. I didn't catch it until the next morning that there was a small leak at the fuel line fitting that left a nice aromatic present for me to clean up. Drained tank (part on me), removed tank, inspected fitting. It appears to be steel (magnet bonded well). The cone at bottom of fitting appears slightly rusted which might have been the source of the leak? Is there a safe way to polish this cone? I would have thought flared copper was soft enough to crush into the spaces, but then gasoline has an amazing ability to creep.

Second question: Should I discard the copper line and buy a steel one? All the vendors I have so far found sell steel.

Thanks!

Eric

 

Cone? You mean flare? Pic needed.

Copper (like aluminum) accumulates stress and will work-harden and crack. Probably be ok for a while, but not proper. Steel will not accumulate stress and won't crack, thus the better choice. Also significantly cheaper.

 

Hope this helps. I did not know what to call the tapered part of the fitting that the flare seals with.

 

Too close-in for me to recognize. Maybe somebody else.

 

Hard to see, but likely an "inverted flare." Off-the-shelf steel brake lines and fittings would work, if so.

If you make your own, a "double flare" end is the proper standard.

 

Another option is a roll of nickel copper tube. Its easy to work with compared to steel and won’t rust. I just ordered 25’ while ago from summit in 3/8” for about $50. I’m guessing you’re 5/16” though so that’ll make it a bit cheaper. Just shape it, flare it (preferably after installing the proper fitting) and install

 

The nicopp tubing is great if you can afford it. The 3/16" tubing is good for brake lines, and can be found on eBay for about $1/foot. However, it gets more expensive as the diameter increases. I would not use it for the larger diameter fuel lines.

Nicopp is a steel alloy that includes nickle-copper-iron in a specific alloy. It bends and flares easily. If you can substitute steel, it's a lot cheaper. I would buy a bender and use steel - https://www.robinair.com/products/four-one-tube-bender - the Robinaire bender works fine, though it's harder as the tubing size gets larger. I use an Imperial tubing bender for 3/8" tubing.

 

I'm with bigjohn. Not having something that can rust is a high priority with all the ethanol in fuel these days. I too used 3/8's from Summit.

 

Not kosher but I'd bet an o-ring in there would seal it well. The delta-P is very low.

 

If that is the fitting on the downward boss of the tank it would be the drain with NPT threads. I can't tell if the picturejust looks like a flare fitting due to the corrosion being pushed away by a flairedhard line.
the fuel pickup is the smaller fitting an inch or so away and has a tube inside the tank to avoid getting clogged.
The flaired hard line won't work on the drain without a flaired adaptor and might be the source of the leak.

 

It is the smaller of the two. Here are a couple other photos that might help. Jw60 gave me a clue as to why a brass fitting will not fit in the fuel drain fitting, which was what I found in the tank. I need to learn these things.

 

Thanks... I do have a double flare set and the copper tube definitely was not flared doubly. Much to learn.

 

Toss the copper line, it is not appropriate for a fuel line for the reasons already stated. It will "work harden", and eventually leak or spray fuel on a hot manifold, which is not a good thing.

The upper fitting in the picture on the right is for the fuel line, and it is an inverted flare fitting. I have used a rifle bore brush chucked in a drill to clean these up a little but don't go crazy with it. Once cleaned it should seal okay with a proper double flare on the line, but I have had some trouble with getting a good seal on some of the reproduction tanks, as the fittings seem to be too deep for the fitting on the prebend lines. The suggestion for a small "O" ring sounds intriguing enough I might try it next time I have trouble.

Don't put sealer on the fitting, it will eventually come loose and cause a clog, don't ask me how I know this.

The lower fitting in the picture is the drain for the tank and it takes a standard brass pipe plug.

 

Inverted flare.

 

I'm not completely clear on this... it sounds like you support the nicopp tubing for brake lines. When you say "I would not use it for the larger diameter fuel lines" I presume you mean the diameter, not the material? It sounds like you still like the material for fuel lines? I just want to clarify that part of your response. And one last request for help on this chain, the copper tubing is 1/4" OD. The steel line from pump to carb is also 1/4" as best I can measure. You mention 3/8" in your reply. Is that a better line size to use or would 1/4" suffice? (My apologies for not knowing if OD or ID is the proper way to describe tubing.)

 

I use NiCopp for everything. Period. I got over messing with bending and flaring steel/coated steel/stainless steel a long long time ago. I might do stainless if I was building a race car, or show rig, but otherwise? Not worth the trouble.

 

You could use Nicopp if you are willing to pay the premium price for the material. I never suggested using 3/8" tubing. No Jeep used 3/8" fuel line from the factory. Even the V8s use 5/16" tubing to the carburetor, and 1/4" for return. I recall the F134 Jeeps use 1/4" and don't have a return line.

 

If you are going to use Nicopp, I suggest you make your own lines. The main advantage of the Nicopp - it's easy to work with.

I make my own fuel lines with zinc plated steel tubing. Not stainless - that's much harder to work with.