Vent nipples in fuel tank

[dirkbalter]

Hello all,
I was ready to paint my fuel tank, when I recognized that one of my vent nipples is plugged (the inside one).
Overall, my tank, inside and out is quite good and I am not ready to replace it yet. In order to clear the possible blockage, I applied air and I tried a wire. I can get a wire down the vent approximately 5in with no luck. 
I read through technical section but I am looking for a bit  more in-side on the routing of these tube and why they are designed this way? (Why two instead of one vent?)
Has anyone had the same problem?
It appears that theses nipple-tubes are brazed into place?
Has anyone redone these?

As always, thank you for your help?

[mrfatboy]

I seem to remember someone here cut a tank in half and posted a picture. You will have to search for it.

I would guess one vent tube come out in the forward part of the tank and the other in the back. That way if the car is tilted uphill or downhill there will always be an air pocket for one of the tubes.

[dirkbalter]

Thank you, let me search a bit more.

[mrfatboy]

How did you determine it was blocked? Visually or put a hose on it and blow? If you can blow through both tubes you are good.

I have heard some people use piano wire to clear out something like this. Be careful of sparks. It’s a gas tank!!!!!😳😳😳😳😳

[dirkbalter]

On the open vent, I can easily blow air through. On the plugged one, nothing (120 PSI). I also pulled a vacuum and it holds it. I did try to open it with a wire but the wire get stuck after approx. 4-5 inches and starts bending.
I am ready to cut the vent tube out.

[mrfatboy]

I would not cut it. Use a flexible wire and chuck in a drill. Fish it the tube and let it do the work slowly.

[dirkbalter]

Good idea. I will give the drill a try. Thanks

[Shvegel]

Yes, one tube is forward and one back in the tank.  I second the "Chuck a wire in a drill" method.  I usually use small welding rod because it is very ridgid.   

[dirkbalter]

Thanks again and FYI, a solid 1/16 SS welding rod did the trick.  I had to tap it through with vise grips inch by inch and the wire eventually broke it free. I had to go approx. 2 ft before it cleared whatever was blocking the vent line.   
Dirk