How to clean out inside of fuel tanks

[kingsransomracing]

I have some aluminum fuel tanks in my 73 gemcraft southwind. The boat sat for a long time (around 19 years) and they never drained the fuel (2-stroke), so looking in the tanks there is a brown layer of sludge all over the inside of the tanks, I beleve to be oil and gas deposits. They wont wipe up to easy. Wondering if anyone has dealt with this before and knows how to remove all the gunk in the tanks so they look clean again. My only option now is to spend $500+ on new custom tanks, but if I can clean them that would be all the better.

[randy77zt]

some radiator shops can boil out gas tanks but the chemical will discolor the aluminum if they are mounted to be looked at.od you could try a couple of gallons of carb dip in them and slosh it around for 2 or 3 days.problem is then you have a hazmat problem then.

[YeLLowBoaT]

Por 15 makes a product that Works Great.....

[Towndrunk]

some radiator shops can boil out gas tanks but the chemical will discolor the aluminum if they are mounted to be looked at.od you could try a couple of gallons of carb dip in them and slosh it around for 2 or 3 days.problem is then you have a hazmat problem then.
What hazmat problem? I dump mine in the next doors back yard.