TOPIC: Cleaning a fuel tank

Finally start work on my Glastron cvx ,took the deck of to start replacing the floor and transom . It has an 18gal steel fuel tank that looks in pretty good shape , only problem is some old thick gas in the tank no rust in side . What is the best way to clean the old fuel out of the tank?Sure would like to save the $300.00 and not buy a new tank.

Wow, thats a good question! I've done plenty portable tanks, but a in boat tank? Whats the consistency the "thick old gas"? How much? Can ya dig some out and a pic? How can you tell as tank has no "cap" for a "look see". Tank gauge out? Need more info here. Solidified mess, or liquid? Smell like turpentine? Theirs solutions to mix it up, them a pump out. Curious what others think.

Took the sending unit out and I could see quite a bit inside the tank, the fuel in the is still liquid and has a strong turpentine smell. Was thinking a good engine cleaner or some other cleaner pour in let it soak and then try to power wash what i can.

I have not tried any of this, but when I was at the antique outboard National meet and talking to an old timer about this ( he had several clean tanks for sale and I bought one, but then asked about my old one like yours) and he said why not use Sea Foam since it is a product you can safely run through your engine in case after several cleanings you are worried about anything left over like if you used other good cleaning products NOT interested to pass through the combustion of the engine. I have not had a chance to finish cleaning mine, so I am also interested in this thread for real advice that is better than mine (since I have not done it yet). Does this seem reasonable if there is no rust and just old gas? Need more expert experience. I could save 2 good built in tanks if there is a tried and true and trusted method.

Very interested in this topic as well. I have two portable tanks that were in Pawpaw's boat, both are red and say Johnson on them, real vintage stuff. One was empty, but the other had some gasoline left in it and it smelled horrible. I would like to know what to use to clean them.

How much is in it? If it still liquid and under 2 gallons, toss in a gallon Acetone (use a respirator), get 2 gallons fresh gas, slosh around for a few days. I just did a friend restored Dorsett that had old gas inboard tank. 12 foot rubber hose, inline 12 volt pump, then hose to 5 gallon tank. Pump it all out 5 gallon can, leave open as rest will evaporate. Then when ready, fresh fuel, Seafoam, Stabil it! Add a see through in line to motor filter (any auto supply, buy spares), and watch for any crap getting picked up.

Talked to the mechanic at the marina today and he said fresh gas should cut through it , but I like the idea of a gallon of acetone also. Will give that a try and let it sit for a month or two to dissolve as much as possible . And when it’s time add one or to glass see thru filters.

Thanks. Good information.

Is the tank in the boat or out. If it's out and you have all the fittings removed then cleaning shouldn't be much of an issue. All the suggestions are good but experience with those old steel tanks taught me that there is always rust lurking. I've spent weeks doing the soaking and sloshing method on an old "cruise-a-day" only to have new gas leak out from a seam somewhere that could never be seen. Rust can be taken out with electrolysis, a simple way. There are products out there that coat the inside of the tank with sealers. Or.... just go on craigslist under boat parts/accessories and find someone selling plastic portables cheap.

I remove the metal fuel tanks from inboard boats and take them to the radiator shop. They cook them out for me in their tank...$50. After that, I coat them with Eastwood's gas tank sealer. At $44.99 for the kit, it's a little pricey but the $100 you'll spend to restore the original the gas tank is a lot cheaper than a new one, assuming you can find one that fits. It's also a lot cheaper than wasting about 7 or 8 days trying to figure out why a boat won't run.

I once worked nearly two weeks trying to determine why a brand new engine was cutting out after about two minutes out on the water....replacing parts, lake testing, repeat, repeat, repeat, etc. Blowing air back through the fuel line into the tank showed that the line was clear...for a few minutes. Apparently, crud that remained in the tank worked it's way into the fuel line as soon and the fuel started to flow and the movement of the boat when out on the water continued to dislodge 50 year old crapola.

Bottom line: The "fix" sounds simple and obvious now but it damned sure wasn't at the time. I lost a lot of income and it ended up costing me a lot more than the money I thought I could save by a simple "dump/wash/dry" approach. I used the tank restoration method outlined above and there were zero problems after that. Since then, all tanks get the same treatment. There is no substitute for doing things right the first time.

Learn from me. I'm a good example of a bad example.

Super idea and our local radiator shop is 2 generations and even Autorized for vintage Mopar radiators. They have done great work for my radiator and A/C needs. Never thought of them for the fuel tanks. I need to call Glen-rays.

Just read all the reviews on the Eastwood fuel tank sealer and it sounds good . A few people had problems but a lot of positive reviews . One hundred dollars sounds better than three to four hundred for a new tank .

The radiator shop??? Who wudda thunk.
Great idea but the crap I buy is way beyond even their expertise. I'd pay $50 for a boil out and then after I hand over the $$ they would tell me it's beyond hope.