Cleaning inside of rusty fuel tank

[RWolf]

What you're most likely running into is varnished gas (i.e. stale gas). On small tanks that I know are ok structurally I put about a cup of gravel and some degreaser/carb cleaner to start with. Then I get a lot of exercise looking like a fool shaking the bejeezes out of the tank for as long as I can. Dump/inspect/repeat until most if not all is removed. Wash thourougly and air dry. After installing, install an extra fuel filter to catch the loose crap that may come out later. Easier to replace a disposable fuel filter than pulling a carbarator apart to get the gunk from there.

Good luck.

 

[pat32rf]

If its a tank that is not easily replacable, such as the one on your 1972 outboard, remove it, dry it completely, rattle some 1/4" lock washers around in it, then plug the outlet and pour a bottle of ABS glue into it. Swish it around so you cover the whole inside of the tank and dump out the excess. When it dries you will have a coated tank, impervious to gasoline.

 

[Bruce-4310TX]

Go to HD paint dept get a jug of phosferic acid - metal cleaner in a clear jug and the fluid is green, clean out the tank an use it straight and yes you can add water to dilute it a little it will eat all the rust and leave a coating and the gas will wash that away. This stuff works great i have a rubbermaid tub with about 5 gals of the stuff for something i need de-rusted. Lowes does not carry it. $14 at HD

 

[patrick_g]

Go to HD paint dept get a jug of phosferic acid - metal cleaner in a clear jug and the fluid is green, clean out the tank an use it straight and yes you can add water to dilute it a little it will eat all the rust and leave a coating and the gas will wash that away. This stuff works great i have a rubbermaid tub with about 5 gals of the stuff for something i need de-rusted. Lowes does not carry it. $14 at HD

Actually that is phosphoric acid and doesn't need to be used full strength to work well as you point out.

A rust removing product sold by the gallon (quarts at some locatons) at autoparts stores and Harbor Freight works really well and isn't very dangerous. It is less hazardous than phosphoric acid.

Kreme is a plastic coating sold by motorcycle shops and auto restoration products vendors. It comes with good instructions and phosphoric acid based cleaner to prep the metal. After cleaning you coat the tank with the plastic liquid and when it cures you have a rust proof tank lining.

I used Kreme on the fuel tank of my air cooled VW dune buggy about 7-8 years ago and the coating is still holding up like new. I had oodles of rust holes and pinholeleaks but all is well now.

Pat

 

[JoelD]

Glad all is well, some great advice on this one.

I like one other suggested take the easy way out and just replace the tank. A bunch less work in the long run, if it was a motorcycle or something of the sort where replacing would be problematic I'd re-line, my brother has done that with a honda CB50 minibike and it worked great.

With a generator, the bigger the tank the better, so maybe when you swapped out you swapped out bigger while you were at it.

Joel