Cleaning pony tank?

Clean it and then coat it with one of the tank relining compounds available. That way you won't have to do it again anytime soon.

I did the detergent, gravel and sand process and then used Red Kote on one and it worked just fine. I did find that I had not quite gotten all the gas out like I thought. When I used a torch to dry the tank completely before coating it, I got one tiny poof out of it!

Please post pictures when you get time!

You can use gravel but I prefer a double handful of old 1/4 to 3/8" nuts. You can fish 'em out with a magnet afterward. If the tank is small enough, you can lash it to a wheel on a vehicle and drive slowly up and down your driveway and listen to everything rattle around. I'm lazy enough I hate shaking tanks😆

I have used Por 15 fuel tank liner kits with good results. http://www.por15.com/Fuel-System-Restoration/products/12/ You don't need to use dangerous acids like muriatic, but rather the etching and converting cleaner that is included. One kit was able to clean and coat about 5 pony tanks for me. One word of caution though, be careful not to coat the threads on the tank, including the filler neck (where the gas cap screws on). The liner will harden and thicken the threads. It will then be next to impossible to screw on the fittings or gas cap, particularly if you allow drips to harden. The stuff is really hard to remove once cured.

One other thing. If your gas tank cap still has the chain attached to it, remove it before using any of the cleaners. Most will eat away the metal that the chain is made of.

Matt

Hope you have better luck with coating compounds than I have had .Some were from 5 to 10 years and the coating came apart and plugged the carb with flakes of coating from the tank.Took that one to radiator shop that boiled out gas tanks.The last tank had the filler almost broken off.Cut tank open with a cutting wheel on angle head grinder and wire brushed with a wheel until it was bare metal and welded it with a little mig looked like a factor weld.Ray

I also accquired a d4 cat from my grandfather and had the same problem. I actually found a small replacement plastic tank but it sits higher and of course is not original like most of us like to keep it but it works and I have the old one that I will just cut open and fix the easy way. The plastic tank is a great temporary and if your not striving for original then it is a good perminant. Just have to modify a bracket and the line to the pony. Hope my alternative helped

I've had good luck filling tanks with nuts and attaching them to the wheel of my riding lawn mower. Big tanks, I've actually clamped them to the wheel on a farm tractor! You have ear muffs on so you really won't go crazy listening to them rattle! Of course your neighbors will surely know you are crazy driving around with a gas or diesel tank attached to your wheel! 😆