Auto Fuel Residue

Okay gurus, this may be a simple one so here goes. I just bought a
project aeroplane and it's obvious the guy was using auto fuel in it.
It's been sitting for about 8 years and there's that great auto fuel
residue all in the tanks, selector valve (frozen), I'm sure in the
lines and I don't even want to think about the carb. Is there a way
to wash that stuff out without removing the sealant? I thought of
buying one of those cheap steamers from Harbor Freight. What are the
thoughts?
Thanks