Fuel tank clean out

[Donnie Coulsting]

Hey guys,
Not an engine issue but does anyone have suggestions on how to clean out a small onboard plastic fuel tank? Boat sat for several years and it was known to have trash in the tank prior to it sitting. The engine has been disconnected and is running on an auxiliary tank. Should i try kerosene or maybe Star Tron followed by a pump out? I have a 12v pump with strainer i can use for the pump out. Thanks!

[99yam40]

what are you calling

a small onboard plastic fuel tank?

I would put some clean fresh gas in it and shake it around for a bit and then dump it back out.
keep repeating until it is not dumping crap out

[panasonic]

Last one I done, someone gave to me, had dried up mixed gas in it for years. Took the fuel level float out, put in some varasol and a handful of galvanized nuts. Slid the tank around on a bench so the nuts would scrape the dried up crap on the bottom off. Dumped that out, some more varasol and shook the s**t out of it for god knows how long.
Dumped that out and then a kettle of almost boiling water with a bit of "dishwasher" detergent as it doesn't turn to all suds like dish detergent....more shaking.

Finally after a rinse with garden hose and blew it out with compressed air ...I put in a cup full of camp fuel shook it around and blew it out one last time. It was then clean.

As you can see...I wanted to save that tank bad enough....lol

I ended up giving the tank to old fellow who was still running a rusty old metal tank.

Good Luck.

[DennisG01]

I'm going to go out on a limb and assume it's a "built-in" tank. At least, I would hope so since flushing out a little portable tank shouldn't take asking the question on a forum!

You should be able to access the tank via the sender - which will give you a better view into the tank. How bad is it?

But, first, can you remove the tank from the boat? Are there removable panels to get at it? This would, by far, be the easiest way and then you do things like mentioned above.

Is the tank currently completely dry? You have to be careful working around gas - and especially the fumes. You can't just use any old pump to remove existing gas as it could very well cause an explosion. The pump needs to be specifically rated for use with gasoline.

After it's all done, keep an extra (or two) fuel filters onboard as a precaution.

[99yam40]

when he said "

how to clean out a small onboard plastic fuel tank?"
, I was thinking either it is a plastic tank for a small outboard, or it is a small plastic tank.
I was not thinking about a built in tank at all.

who knows for sure

[DennisG01]

when he said "

how to clean out a small onboard plastic fuel tank?"
, I was thinking either it is a plastic tank for a small outboard, or it is a small plastic tank.

I initially thought the same thing, But then I thought... "Why would someone ask how to clean out a little, portable, plastic container?" 'Course, maybe I was thinking too logically...

[Donnie Coulsting]

My bad. It’s an on board below the deck tank that cannot be removed. I am assuming there is an inspection plate for the fuel sending unit as this is on a friends boat but regardless i know there is access to the engine supply line as it was previously disconnected.

[99yam40]

I would think there should be some companies around there that do this al the time.
steam or hot water cleaning would be my thought.
they do this all the time on tanker trucks and railroad tankers

[DennisG01]

My bad. It’s an on board below the deck tank that cannot be removed. I am assuming there is an inspection plate for the fuel sending unit as this is on a friends boat but regardless i know there is access to the engine supply line as it was previously disconnected.

There's no way to get to it through a removable floor hatch (screwed down)? Or pull it out rearward? In many boats, it's easier than you might think at first.

Otherwise, yeah, a couple gallons of kero or diesel and let it in there for a while - let nature take it's course with the natural movement of the boat sloshing it around. Siphon back out what you can - take a look - repeat if needed. You might be able to get a rag in there with a stick (zip tie the rag to the stick, for example).

[99yam40]

There's no way to get to it through a removable floor hatch (screwed down)? Or pull it out rearward? In many boats, it's easier than you might think at first.

Otherwise, yeah, a couple gallons of kero or diesel and let it in there for a while - let nature take it's course with the natural movement of the boat sloshing it around. Siphon back out what you can - take a look - repeat if needed. You might be able to get a rag in there with a stick (zip tie the rag to the stick, for example).

I would think E 85

or even E10

would be a better cleaner than diesel or kerosene.
some ball bearings in there to roll around might help, and be easier to get back out with a magnet

[Jason2tpa]

All below deck tanks are removable....just a matter of what needs to be removed to gain access, which depending on the deck and below deck access, could include removing the entire deck. And if that’s the case, your friend is puckered. Unless of course he chooses to use the tank despite not confirming its interior status. If trash got in the tank (whatever that means), so too can water. If stagnant water is in tank, so too is mold. No bueno.

[DennisG01]

I would think E 85

or even E10

would be a better cleaner than diesel or kerosene.
some ball bearings in there to roll around might help, and be easier to get back out with a magnet

Of course, if those ball bearings happen to make a spark when they bang into each other, that'll clean the tank out REAL fast! Diesel would be the safest in this regards and actually does a pretty good job of cleaning things.

I'm honestly not sure if new gas would clean old, gummed up gas? I mean, if it did, carb's would self clean themselves, right? Just wondering outloud there. But from that standpoint, I'm not positive that diesel would dissolve gum, either. I've never tried it for that.

[TownsendsFJR1300]

I've used small "river rock" stones with good results.. Stones are maybe 1/2" in diameter and don't spark.
Not being perfectly round also seems to work better while doing actual cleaning.

Those and gasoline with a final rinse of fresh water, flushing numerous times, usually give good results..

On occasion, I'll put a rag with a long paint mixing stick into the tank when an area has to be literally rubbed...

.

[99yam40]

I've used small "river rock" stones with good results.. Stones are maybe 1/2" in diameter and don't spark.
Not being perfectly round also seems to work better while doing actual cleaning.

Those and gasoline with a final rinse of fresh water, flushing numerous times, usually give good results..

On occasion, I'll put a rag with a long paint mixing stick into the tank when an area has to be literally rubbed...

.

I am thinking all of this would be very difficult to do on a built in tank without taking it out of the boat.
in a console is one thing, just pull the console,
but below a fiberglass floor, I do not see any of these things being done without cutting the floor and removing the tank

[DennisG01]

I am thinking all of this would be very difficult to do on a built in tank without taking it out of the boat.
in a console is one thing, just pull the console,
but below a fiberglass floor, I do not see any of these things being done without cutting the floor and removing the tank

Probably would, largely, depend on where the sender unit is located. If it's in a more open area, it would give enough room to get your arm in there. But we still are only guessing at this access - need more info Donnie! For one... "why" can't it be removed? Screw down floor hatch or not? Some people look at a large, screw-down floor hatch and think "Oh, I'm not removing that big thing!" Yet, it's very easy to do.