I have a 110 that say for 15 years and the tank on the inside is rusty I put some gas in and shook the tank then poured it out a few time but the in line filter is still looking nasty. What can I do I can't really get in there with a wire brush

 

There are several tank cleaning/sealing kits out there, the best I heard of was a 3 part system this dealer told me he had used. The first part is a chemical cleaner/etcher that breaks loose the rust and preps the metal for sealing. Part 2 neutralized the acids, and "primed" the metal for sealing. Part 3 was a clear, varnish like sealant that coated the metal and sealed any pinholes. This was a few years ago, so I can't remember the name of the stuff, sorry. But one thing I will tell you to stay clear of is that stuff called Creme, it is a white, latex like coating , it doesn't really clean out the rust, just seals it in, I have heard a lot of guys cursing it for coming loose in little chunks and plugging filters, petcocks, and carbs.
Talk to a dealer, check parts catalogs like Dennis Kirk, see what they carry.

 

I have used the KREEM on a couple of tanks with good results but the last one I tried had pinholes rusted and the acid ate through the tank. Kreem cost about $35. You could try a plastic tank but they run about $200.

 

Another trick to try first, before the store bought treatments... seal all the openings, put a quart of gas in it, with about 100 3/8" hex nuts and roll the tank around ALOT. Gets the big chunks off pretty good.

 

What about clr

 

I had a rusty tank on a generator and i used purple power rust treatment from advance auto parts. Just a thought but it worked for me. Ospha coat is also a good rust treatment, it eats rust pretty fast and turns the metal black.

 

i like the nuts and bolts trick works everytime!!

 

Buy a gallon of "EVAPO-RUST" http://www.evaporust.com/ I buy it on ebay for about $20/gallon. Fill the tank, let it sit a day or two, give it a shake now and then. No fumes, wont hurt the paint, wont hurt your skin. You can pour it back into the gallon and reuse it until it stops working, then you can dump it down the drain. I've done four ATC tanks with it, a couple were really rusty and they come out like new. You wont be disappointed.