So my Trail 90 fuel filters were looking like this. I redid that Trail 90 a long time ago and I really didn't know much about bike rebuilding. I should have addressed the rust in the tank before I had it painted.
The inside of the tank is nasty.
I decided to try Evapo-rust. It's not real cheap; it's about $22 a gallon, but it is available at O'Reilly's and other local stores. I figured it was my best bet to not hurt the paint and clean the tank while it was still mounted to the bike. It's only supposed to attack the rust and not the parent metal. This stuff is not caustic and nasty at all, but will it work?
I can basically fill the tank with the gallon of Evapo-Rust. It seems to be doing something it's not dramatic at all just some floaters. I did agitate it a bit and let it set over night.
So I dumped it out the next to see what was going on. I used this filter body not to filter it, but just to join to fuel lines.
They say it can be used until it's black. I think I used it up.
Time to flush with water. Again this stuff is supposed to safe enough to dump on the ground.
I flushed and fished around with a magnetic to get all the floating parts I could.
I dumped the used stuff down the sink. The Evapo-Rust didn't hurt anything, but there was stall gas smell that it absorbed though.
The first treatment did a lot, but I ran second treatment and the tank came out this nice. I think if I had prewashed and shook a bunch of nuts inside the tank to get the worst of the loose rust out first, then the second gallon of Evapo-Rust may not have been needed. The Evapo-Rust works as well as advertised and I will be using it again.
I did immediately fill the tank with fresh Seafoam treated gas.