Removing varnish build-up from gas tank

[petemcshane]

Have a 60 yr old cruiser with two gas tanks that have gooey varnish deposits in bottom. Does anyone have a technique for removing this without removing tanks? There are no access ports on the tanks other than a 2" spout. Any suggestions are welcome. Thanks.

[mike kelly]

if you cant take them out, it doesn,t leave yuo with to many choices. I would put a gallon or so of acetone or laquer thinner in each tank let set awhile.drive around on a temporary tank if you can.Then drain it. it might take two times The thinner will disolve it pretty well.Get a good fuel filter to, change it often until its cleaned out.

[Ed Harrow]

I'm told matches work really well ! Otherwise what Mark said should do just about as good a job.

[dasboat]

Everything I say is a pure guess.Add a suffecient amount of the fule line or injector type cleaner(maybe a carburater soak type liquid) and stir/shake/mix somehow,then pump out.
I would add some liquid to reduce the volitility of the liquid(especially if there is still gas in the tank)before I began to pump.vegetable oil for example may do the trick.
Then you could rig a diaphram type pump and pump it clean.
Gluck,Das

[Frank Wentzel]

Fuel injector cleaner has essentially the same composition as lacquer thinner but lacquer thinner is a darn sight cheaper. You will probably need at least two applications. Be sure to do an extra rinse after you think the tank clean to get the last of the residue. By the way, you can put some lacquer thinner in your gasoline regularly to keep the system cleaned out. It will increase the octane rating of your fuel as well.

[PilotArt]

Alcohol works very well in getting the gum and varnish out of fuel systems of outboards and lawnmowers stored too long with old gas.

[Dale Harvey]

Only use acetone or laquer thinner on metal tanks! After your done, install Racor two micron filters. Anything less, like the cheapo five micron spin ons, will pass fine powder that will clog jets and fill carb bowl. The powder won't show up 'til you dissolve the the gunk, and it won't dissolve. Don't know if its lead residue, metal oxide, or dead algae.

[TomW]

I have a Ford Model A with the same problem. A friend sugested to have the gas tank steam cleaned that would clean the tank out and not harm anything.

[petemcshane]

Thank you all for your suggestions on removing varnish from the gas tanks.

[John B]

I vacuumed out the fuel tank on a Model A when I was young and stupid.
I reeeeally wouldn't recommend it (unless you like flame throwers.)
PS, What you do with the Model A is leave the stuff in there, shove a 1" long piece of copper tube in the tap so it protrudes up off the bottom of the tank, and fit a fuel filter.

[mgd1961]

well i have first hand and recent experiance on this one, after removing the tank, droping a couple of chains in it, useing Hydoseal carb cleaner, acitone, laquer thiner, caustic radiator cleaner, a rain dance a pryer or two, picking up the draw tube off the bottom and so on, everything was a BIG waste of time and money, After more filter cartrages than I can count, and three seasons sitting on a mooring wondering what to try next, I replaced the damn tank and have had the best season ever. Just bite the bullet and do the right thing. and to top it off the filters always clogged when the weather was less than calm " stured up the junk" dont ya know