Cleaning built in fuel tank for 97 Johnson 60hp

[lacseul.]

Is there a good way to completely clean and empty a tank? I don't want to take the entire back deck apart, but will if that's the only way. Any input is appreciated.

I have been experiencing some rough motor running issues - not all the time though, the way out it idles well and when I bring it up to 3000 rpm's or so my (Johnson 60hp - 97) shakes a bit, doesn't want to go all out, but stop and fish go to next spot runs perfectly normal. (then of and on all day) I use good 91 non ethanol gas- So far - I have cleaned the carbs, new fuel filter - new filter for water separator, all new fuel lines primer bulb - checked spark and compression are good -

So now - I want to try and completely empty/clean the gas tank its on a C-liner fishhawk- 1650 tiller (2005)
Thanks,

[ezmobee]

I'd try running it on a known clean portable tank with a known clean fuel line to rule out (or rule in) your built in tank as the culprit.