My CBR fuel tank is rusted inside and I need to clean it before it gums up the fuel system. I've gotten all the heavy pieces out and cleaned out all debris possible. I put some white vinegar in the tank along with some other fuel cleaning elements. I left the nuts and bolts in the fuel tank and put it in the back of my truck for a week in hopes of the nuts sliding around in the tank and cleaning the inside. This helped a little but still rusty. Since then, I've tried putting muriatic acid inside. This does a very good job of cleaning the inside of the tank of all rust however if I leave it in the garage overnight, the next morning the entire tank will be rusty again. I've also tried putting WD40 in after the acid, rust still comes back. I've tried putting acetone and also water, rust still comes back. The rust that comes back is nowhere near as bad as it was to begin with, but I can wipe the rust out with just a finger or a towel. Obviously I cant reach the entire surface of the inside of the tank by hand so I am lost. I feel like I've tried all the "how to remove rust from tank" videos on Youtube and the rust still comes back.

What am I missing? What chemical will prevent the rust from coming back? Or do I need to flush it with muriatic acid once more and then fill it completely with fuel to stop the rust from coming back... I have attached a few picture of the inside of the tank. The pictures titled Tank3 and Tank4 are after sitting in the garage overnight.

Thank you in advance

 

You need to completely rinse out tank to remove all traces of acid when done. It will actually cause rust. Also make sure ALL rust is completely gone at end. Electrolysis is best method for removing rust as it only attacks rust and leaves good metal alone.

Need multi-step treatment after you're down to bare metal. Some sort of rust-inhibitive layer along with protective coating. Check out POR-15's kit.

 

To rust, it needs oxygen and water - you need to eliminate one or both. Your problem is you're cleaning it down to bare metal and then leaving it damp. Iron is one of the most reactive things on the planet - ever used a metal fire starter? The sparks are just bare iron with the rust chipped off being exposed to the air - The iron in your steel tank is no different.

So either put some gas in and shake it around then seal it, or spray it with an anticorrosion film, like CRC marine corrosion inhibitor. You want to get it good and dry first though - blast it with a hairdryer for half an hour or something. Don't let ANY water or water based products near it once it's clean - it will flash rust immediately.

 

To add on to what the others have said, if you are doing this work outside and especially if you live in a humid region, what you are experiencing will be exacerbated.

 

So something like this link from amazon?


Some kind of 2 or 3 step process? Also would I put in the black coating as well or is that just a paint if I was restoring some kind of exterior metal? It is true that I have just left it damp or wet after using the acid as I have never dried it so I will remember that next time.
As for sealing it, in the first process of using the acid, I burnt up the lock on the gas tank cap so I have ordered one and its on the way. I was worried that the acid or rust removing chemical would eat through the rubber gasket for the fuel pump hole so I left that end open as well.

Thanks

 

You just need a jug of evaporust - You're using the most toxic thing you could possibly try. Stop with the acid - you're going to destroy it. At this stage you could just use vinegar, then rinse it out with isopropyl alcohol, then put some gas or diesel in and swish it about to coat it, then seal the tank with a plastic bag or something.

Normal gas tanks have no lining - they just don't have any water in them either.

 

That's their external rust kit for bodywork. You want the "motorcycle fuel tank repair kit" which replaces final layer with some sort of coating rather than paint. It's not as thick as Kream or KBS or Red-kote or other brands which is just fibreglass resin. Those don't stick too well, especially without surface-prep stuff that POR-15 comes with. I've found it to work better than anything else. Doesn't flake off and clog your fuel system after couple of years. Although I prefer nickel or tin coating myself. Metal's much more durable than plastic, especially when it comes to chemicals.

https://detailingconnect.com/product...ank-repair-kit

 

Thanks, I will try this when I get off work. Regular vinegar or white vinegar? If it matters...

 

White vinegar is chemically created acetic acid - it's great for gently cleaning rust. Just remember the key is to get the tank dry once you've got the rust out and then protect it from any moisture.

 

Okay, so I rinsed the tank out with white vinegar and then got it as dry as I could with a heat gun on low and compressed air. The tank was pretty dry inside and what little was left at the bottom, I wiped with a paper towel. I then left the tank on its side with a fan blowing into it overnight in the garage. The inside of the tank now looks like this... Almost all of the heavy deposits are gone so now I am just worried about the thin layer of rust that will effectively mix with gasoline as it goes through the fuel pump. I guess I will have to try that POR15 kit for the motorcycle fuel tanks. Unless you guys think this isn't bad to just run through the new filters I have to install. Thanks