"built in " gas tank cleansing??

[levi_tsk]

ok so i just got this boat REALLY cheap and i dont want to pull the console to take the tank out (its built in under it ) floors fine hulls solid no real need to but looks like all the fuel evaporated out of the tank, how ever judging from the funk coming from under the console, theres bound to be some varnish left over from it sitting. the engine is an auto mixer so there no 2 stroke oil in the fuel tank just funky gas resdue and the boat and motor sat for 6 years

the tank is 27 gallons according to my calculations

any suggestions ?
i just got through rebuilding the carbs on the engine (60hp tohatsu) and i dont wanna gum em back up
what about 3 gals of e85 poured in there and let it sit for a couple days and use the fuel hose and primer bulb to drain it out?

 

[Beefer]

Re: "built in " gas tank cleansing??

three gals won't do it, unless it's a 3 gal tank. I think what I would do, is first remove the screen filter from the pickup tube, as they are relatively small and will clog fast. Then I'd install a couple of progressively finer inline fuel filters. Something like an automotive fuel filter first, as they have a large surface area, and then a see-through filter, and then a fuel water separator. Cut into the fuel line, and mount those, and then run the boat. After each outing, check the glass filter to see how much, if any, crud you're breaking down. Don't worry about cutting into the fuel lines, they are most likely caked with the crud as well, and you'll need to replace them as well. Fuel line is cheap. It might take a week, or it may take a season to clean it all out, but eventually it'll be clean. Keep the tank full, and if you don't plan on using it all the time, add some fuel stabilizer (Stabil etc.) to preserve it.

Be sure to check the condition of the existing fuel line, or better yet, pull it, and start with new. Yes, you'll be replacing it again once everything is cleaned out, but never a bad thing to start with new.

Keep spare filters on board until the tank is clean. If any of the filters clog while you're tooling around, at least you'll be able to change them and get home.

 

[NYBo]

Re: "built in " gas tank cleansing??

three gals won't do it, unless it's a 3 gal tank.

Actually, it may be enough. The gunk is going to be on the bottom so the whole tank doesn't need to be filled. But that 3 gallons will quickly get full of as much gunk as it will hold, so the process will have to be done several times until the stuff comes out fairly clean.

 

[levi_tsk]

Re: "built in " gas tank cleansing??

well the fuel lines already been taken off an thrown away so itll be getting replacedno matter what. i thought about running the 3 gals in there and letting it sit for a day or two pumping it out and installing a couple of filters like Beefer had suggested but im kinda in agreement with NYBo that all the crud is in the bottom and it wouldnt be neccessary to foul up 27 gals (or more) or any more than is needed. id rather run 6-9 gals of gas through there 3 gals at the time and throw that away or put it in my truck than foul up a whole tank and hope it gets clean...

according to my calculations 3 gals is 693 ci and since my tank is 26"x20"x12"deep 3 gals would fill the tank up to about 1 1/4" deep just enough to cover the crud

but what do i put in there for the best effect??

 

[fishrdan]

Re: "built in " gas tank cleansing??

Buy a cheap electric fuel pump to run the fuel through a filter, then back to the tank. Fuel goes out through the filter, then to the pump, then back into the tank. Buy some cheap clear vinyl hose at Home Depot and plan on throwing it away when done. I'd just use a water separating fuel filter and several extra filters. You are going to want to buy it anyway and the filters are pretty cheap,,, and big, lots of surface area.

You are going to need to agitate the fuel around in the tank, probably tow it around a bit to get the fuel sloshed around. I'd probably run the pump for an hour or 2, then pump a clear jar full of fuel to see how much "stuff" is still in there. Cutting open the filter will tell you how bad the tank is. Though, the real test is going the be out pounding waves and breaking loose all the stuck on stuff.

You said you "could" get the tank out, how hard would it be to remove it? It might be quicker, safer and better, to just take the tank out and clean it. Put some cleaner in it (Simple Green, Purple Power, etc) and go in through the sender hole to scrub it out with a rag attached to a rod, kind of a mop. Scrub it out good, flush it with water several times, then dry it out with the rad-n-rod. If doing this, I would run compressed air through the tank for an hour or so to make sure all the water is gone, then use a flash light while tipping the tank to make sure all the water is gone. If you don't get the water out, ethanol will find it.

 

[Beefer]

Re: "built in " gas tank cleansing??

well the fuel lines already been taken off an thrown away so itll be getting replacedno matter what. i thought about running the 3 gals in there and letting it sit for a day or two pumping it out and installing a couple of filters like Beefer had suggested but im kinda in agreement with NYBo that all the crud is in the bottom and it wouldnt be neccessary to foul up 27 gals (or more) or any more than is needed. id rather run 6-9 gals of gas through there 3 gals at the time and throw that away or put it in my truck than foul up a whole tank and hope it gets clean...

according to my calculations 3 gals is 693 ci and since my tank is 26"x20"x12"deep 3 gals would fill the tank up to about 1 1/4" deep just enough to cover the crud

but what do i put in there for the best effect??

You wouldn't be wasting any fuel. That's what the filters are there for. You could as fishrdan says polish the fuel yourself as well. I did mine with a cheap-o handpump and 2 filters that cycled the fuel through the tank. The reason I don't think that 3 gals (or 3 gals at a time) would do the job, because the walls are probably coated with the crude too, not just the bottom. You need to get enough ethanol fuel in there to breakdown the built up crud, and I doubt it'll be all cleaned in one 'application'. Just keep spare filters on hand, like I said.

 

[levi_tsk]

Re: "built in " gas tank cleansing??

Buy a cheap electric fuel pump to run the fuel through a filter, then back to the tank. Fuel goes out through the filter, then to the pump, then back into the tank. Buy some cheap clear vinyl hose at Home Depot and plan on throwing it away when done. I'd just use a water separating fuel filter and several extra filters. You are going to want to buy it anyway and the filters are pretty cheap,,, and big, lots of surface area.

You are going to need to agitate the fuel around in the tank, probably tow it around a bit to get the fuel sloshed around. I'd probably run the pump for an hour or 2, then pump a clear jar full of fuel to see how much "stuff" is still in there. Cutting open the filter will tell you how bad the tank is. Though, the real test is going the be out pounding waves and breaking loose all the stuck on stuff.

You said you "could" get the tank out, how hard would it be to remove it? It might be quicker, safer and better, to just take the tank out and clean it. Put some cleaner in it (Simple Green, Purple Power, etc) and go in through the sender hole to scrub it out with a rag attached to a rod, kind of a mop. Scrub it out good, flush it with water several times, then dry it out with the rad-n-rod. If doing this, I would run compressed air through the tank for an hour or so to make sure all the water is gone, then use a flash light while tipping the tank to make sure all the water is gone. If you don't get the water out, ethanol will find it.

brillaint fishrdan!! brillant!! never thought of using the pump and that was my hang up - how to adgitate the liquid in the tank?

i like the idea of cycling it through the tank and i already have one of those cheap pumps laying around in the garage and i may already have a water seperator filter laying around too (ill have to look) but yeah i really like this idea and i think ill got this route

as for getting the console off and pulling the tank it would end up being a pain in butt and taking ALOT longer as the console is glued with 5200 or the like to the deck and then screwed down and i cant really tell how the tank is fastened but it doesnt move at all so im thinking its glued down too

thank you to everyone for all the great suggestions!!!