How do i clean built in an aluminum fuel tank?

[blowin' insider]

I bought an older 21' double eagle that has sat for 10 years with roten fuel that's turned into a thick sludge on the bottom of the tank, is there anyone on this site with any experience on cleaning out this sludge? I've tryed acetone but there's still tar goop left . I've flushed close to 100 litres of fuel through the tank and I'm still getting globs of tar . Any help at all would b greatly appreciated
Thanks everyone

 

[chromatose007]

I cleaned an old diesel tank with methyl hydrate.
Sounds like you need either pros or remove the tank.
Gl