Red kote!

For all of you who have used Red Kote in the past!

A few weeks back I decided to seal my gas tank with Red Kote because I saw very faint rust inside of it. The container says to let it sit for 24 hours or so and also that the curing process is complete when you cannot smell the sealant anymore. Well...I can still smell a faint odor of the sealant when I take a wiff after about 3 weeks of letting it sit. Is this good, bad, terrible?

 

Chances are that you set the tank down, after pouring out the surplus, and it was in such a position that the surplus on the vertical walls ran down and pooled in one area.
If I remember right, the instructions warned against that, because the pool of fluid forms a skin, which inhibits vaporization of the solvents (MEK etc), and doesn't dry out.
What you are doing with Redcote is putting a paint film on the inside of the tank. If the paint is not dried out, gas will permeate the film and cause lifting.
Your best bet now is to set the tank in a hot, dry place, and let it set. 150 deg F would probably do. If it were summer time, I'd suggest that you set it out in the sun for a week. Eventually the pool will dry up, and the smell will go away, and you should be good to go.
Another thought is to figure out where the pool is, and set the tank over a 100 watt light bulb, with that portion of the tank about six inches above the bulb. Check the temperature after a while, and see if it is hot to the touch, but not so hot that you cant keep your hand on it for a few seconds. Adjust the spacing accordingly.

CZ

 

Addendum,

Once you get the tank heated, an aquarium air pump, with it's output tube placed inside the tank, and all the tank openings open, will help remove the VOC's from the inside, and help the drying process.
Or a chimney made out of a cardboard tube, affixed to the gas cap opening, and the petcock openings uncovered, might use convection to induce air flow through the tank.

CZ

 

OP lives in Texas.

Set it in the sun for a while. Don't let it get too hot.