fuel tank cleaning? cheap?

[Bus Ted Knuckle]

The muriatic acid works great. BUT it is rough stuff, do it outside. You can get it at hardware stores, it is used to clean concrete. Mix about one gallon of acid to two or three gallons of water (I usually wind up putting about 2 gallons of acid, and about 6-8 gallons of water). Put a piece of chain in the tank, SEAL ALL HOLES, and slosh. My favorite way to slosh is to throw the tank in the back of my driver truck and go for a drive. Drive a few miles, then flip the tank over and drive some more. Works good if you do it while running errands around town. I use a chain because it is a heck of alot easier to remove than gravel. This next part is VERY IMPORTANT:

Dump the acid/water out of the tank (in what ever enviornmentally way you choose), fish the chain out with a stiff piece of wire, and dump a couple of boxes of Arm and Hammer baking soda (like what your wife uses in the refrigerator) and fill with water. This neutralizes the acid. If you don't nutralize it, it will form even worse rust in your tank. flush and fill with fresh water several times and use a shop vac to suck out what rust you can't shake out.

Leave the tank open in the sun a few hours to dry.

Bada Boom, Bada Bing...

Fresh clean tank.

Can't stress enough though, be careful with the acid. It'll put the hurt on you.