how to flush a gas tank out if its cruddy(BOAT TANK)?

You'll probably need to remove the tank unless you can do it manually with a siphon hose......but to do it properly AND give the tank a good inspection while you're at it.........ya oughta pull the tank.

(I sure hope you don't have to cut the deck.....some builders are major jackasses when it comes to tank construction and installation).

.....but whatever you do....don't use one of those electric pumps like Jabsco makes for pumping oil from the crankcase. Electricity and gasoline fumes just don't mix.

Have you smelled the tank? Does it smell like varnish?One of my pals had the same problem as you and he used carburetor cleaner....dumped some in the tank a couple of times and kept washing it out. He fixed it too....but he also rebuilt the carbs.

Good luck.

PS......I went looking for a solution to your problem and this looks pretty good.........from Northern Tools.....check it out.....it''s better than a hand siphoning (no mouthfull of gas)...and it looks safe...(non-electric).

http://www.northerntool.com/webapp/wcs/stores/serv...

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As the countless solutions have stated plenty relies upon on the motor vehicle. The minimum is you may desire to siphon out as much as a danger and then replenish with clean gasoline. that could desire to dilute adequate to not reason a topic. What might desire to take place however is it might desire to reason issues of the O2 sensor, the catalytic converter, or the gasoline injectors. If this is an older motor vehicle with a carb and no catalytic converter - siphoning might desire to be nice(remember gasoline is incredibly undesirable for you if it gets on your physique - be careful). extra recent motor vehicle - drop the tank and flush with clean gasoline.