Gas tank cleaning

Does anyone know the best way to clean out a gas tank? I have a 42 gallon gas tank thats built into the boat. I really dont want to rip up the deck to remove it. Is there a way to clean it out? Are there any special techniques to doing this?

Re: Gas tank cleaning

lots of posts on this. I assume you are on a trailer?
to empty the tank, raise the tongue, and run the gas line from the tank out the plug in the stern; get a syphon going or use the bulb to pump it out. Watch for streaks to see if the old gas is salvageable.
(or hire a company who pumps it out, cleans it, and puts it back)
(or buy a pump but be sure it's made for gasoline)
when it's empty, remove the sending unit to get access, and spray a can or two of carb cleaner in there. swish it around, by raising/lowering the tongue, driving around like a cazy man, etc.
Then raise the tongue and pump that out; dry the rest out with a rag SECURELY attached to a stick.
check your fuel pick up and all lines and seals while you're at it.
Use a flashlight, not a candle, to see what you are doing. (seriously, disconnect all power in this process)

Re: Gas tank cleaning

There are also products that you can put in the tank to clean it. All are very acidic or caustic, and will eat straight through a tank if you aren't careful. POR-15 makes one called metal ready. Alternatively, I have just used a mixture of lye and water in the past on motorcycle tanks. Again, you have to put in it, slosh it around, and watch it carefully. Once you can see shiny metal, get it out and neutralize it. I'd go with Home Cookin's method first since the tank isn't removable and see how that works.