Topic: Fuel Tank dilemma

[mrmach5]

Have my 75 550 down for some winter maintenance, and upgrades. Emptied my fuel tank for inspection, and just some very light rust, however in the bottom of the tank is a black coating (just the bottom). Is this factory or did someone coat this, only did not  rotate the tank to evenly distribute. I was considering using redcoat, but warns against coating over a coating. I don't want to botch the job so perhaps I'll just clean the tank with Apple Cider Vinegar, put a good fuel filter on and forget about it.

[ekpent]

Is there any sign of rust through or repairs from the bottom underside of the tank like JB Weld or something. Is there a chance it may be an old coating of varnish if the gas was ever left in there long enough to evaporate at some time in its past ?  Is it black black or maybe a really dark brown ?
  PS-Welcome to the forum 

[Johnie]

Welcome to the forum. Some of the citric based rust removers will leave the bottom of the tank dark. Possibly someone just used a little of that type cleaner to remove a little rust on the bottom. If you are seeing clean gas in the bowls I would not mess with a liner if all is well.

[lucky]

In your heart you know you should remove that old coating, clean it and then use Caswell's two part epoxy with white colorant so you can see the inside of the tank.

With the Caswells sealer the tank can have light rust on it.
Caswell told me that.

You can get the white colorant from TAP plastics. It is a 2 oz. jar and it is premixed. About $6.00 Caswell approved that for me.

[mrmach5]

Underside of the tank looks good, but some type coating on the inside bottom, that is black, black not a residue. Just wondered if that came from Honda that way or were they all bare steel. I heard acetone would dissolve old coatings, could try that then clean, and recoat, or just leave well enough alone, put an good inline filter on it and ride, rather than risk botching the job.
Thanks for all the input!

[ekpent]

Anything that you put in there that is strong enough to cut a coating will also be dangerous for the paint unless your very careful.

[Duanob]

Yep what ekpent said.

You can use straight acetone it works great on removing old liners. It's not cheap but a couple of gallons will work just seal the tank good and move the tank in different positions in a 24 hour period, then drain in a responsible mannr and dispose of properly.

Then use some phosphoric acid based derusting compound, like etch-n-prep found at Home Depot to remove the rust. ALWAYS remove the rust before re-coating I don't care what Caswell says. I like their coating but that's just bad advice. Rinse with mineral sprits or something like that to keep from flash rusting.

Then check for pinholes or leaks, if none then you're good to go. You shouldn't need to line it. If you have holes then yes I like Caswells, just follow the directions to a T. Also, if you have pin holes then you will probably be repainting the tank anyway. Once the inside is lined, you can sand and 'bondo' the affected area, make it smooth then primer and paint.

[mrmach5]

Yes good point regarding the potential for paint damage,,,,, the tank on the outside is the flake sunrise orange, and looks awesome,, I would be sick if I screwed it up.

[ekpent]

Sounds nice. I have done some radical tank cleaning etc with original paint but that's outdoor stuff with lots of wax on the tank,lots of  water, expandable rubber plumbers plugs, tight fitting petcock plugs or covers etc.
  Is there any way just out of curiosity that you can post a pic of what you are seeing in there ?

[ekpent]

Mach - follow Ekpents advice and remove the liner. BUT, first wrap your tank in Saran Wrap, then tape the seams with blue painters tape. This will protect your paint, coupled with some care in handling. Wrap the filler neck with tape, then wrap, then tape. Triple up the coverage in this area to prevent any contamination.

Use the same care when installing the liner. You should/could even un-wrap and re-wrap as an added precaution to prevent any possible leakage.

Never said remove the liner yet till we can have a peek at what it is. Sounds kinda weird at this point with just the bottom "black". Never have seen a black tank liner on the market ??
   Just a couple of pointers if He starts tossing chemicals in there   

[jonda500]

Welcome to the forum. Some of the citric based rust removers will leave the bottom of the tank dark. Possibly someone just used a little of that type cleaner to remove a little rust on the bottom. If you are seeing clean gas in the bowls I would not mess with a liner if all is well.

+1 I'm with Johnie - if it aint broken don't try to fix it

[Duanob]

Yup, credit where credit is due. Forget Ekpent, listen to Duanob. :-)

Thanks! I've only done two tanks but I am pleased with the outcome of both so far. One lined and the other just de-rusted.

Jonda, the problem with crap in your tank is you will have many problems down the road. It always makes it way into the carbs.

[jonda500]

There are lots of tank cleaning methods, an alternative method I like is to let the tank dry, seal the fuel outlet, tip a large bag of aquarium gravel in(I used M6 nuts), seal the filler hole, wrap the tank thoroughly in underfelt and gaffa tape, stick it in a clothes dryer on fluff cycle(no heat) for a few hours, tip out the gravel, blow out all the debris with compressed air, flush with diesel and then with petrol, done.