[Phil Waterman]

Hi Casey

Great pictures inside the tank, looks like the tank is in good condition other than what ever that gunk in the tank is. This doesn't look like normal varnish from evaporated gas, almost looks like something was dumped into the tank. Is all the gunk on the bottom of the tank?

Robs comment about taking it to a radiator shop is a good one, but be careful some shops use an etch solution which is OK on brass used in radiators but might take the coating off the steel.

So back to the gunk, it looks like the your fingers have made marks in it, can you get some out of the tank with out scratching the inside of the tank? If so try you might try the following to see if it will dissolve:

Really hot water ( I sort of suspect this may work)
Acetone
Straight alcohol
Automotive paint gun cleaner

Reason I suggest doing this on small samples is so you don't make the problem in the tank worse, for obvious reasons don't mix them together.

I would not use anything abrasive, as it looks like the steel in the tank is other wise in good condition.

One of the old methods of dealing with a problem like this was to use a gas tank sealant to seal the junk down, but as the new fuel mixes have dissolved two older type of tank sealants resulting in the same type of problem you already have I would not suggest using a sealant.

Please keep us posted on how you make out as your problem is one which any of us can end up dealing with.

Cheers Phil