clean out gas tanks

[GONEFISHINTODAY]

got another project.

has had gas in it for 6 years. I'm sure tanks have varnish build up.
anyone have tips on how to clean these out. there are two tanks under the rear deck. don't think they will come out without cutting the deck?

it's a 90 ranger 360 v.

thanks

[apenland01]

I bought a used Ranger and it had gas in it for 3 years. Replaced the fuel lines, primer bulb and fuel filter. Had all of it sucked out and just put in fresh gas using Quickleen and Quickare every tank and haven't had any problems.