I am working on a 248 chris craft that someones ex wife poured something in the tank it has a gelatin like apperance and appears impervious to gas kerosene detergent you name it I have tried to dislove or at leest break it down....any ideas i am plumb out of them Ed

did you try Methyl ethyl ketone(MEK) or any other paint thinners?

I Replace the tank no matter what you use to get it out some will still be left and WILL cause problems in the future.

She burned down his pole builing too...they can prove it was arson but not that she id it....it turned out the gunk was anti frezze plain old green antifreeze seems that it turns to gel when it mixes with gas

If the glation floats, flood the tank with water and hope it will flo out the sending unit hole. If not , try and pump it with a pool cover pump.