Coating gas tank?

I am thinking about coating my 1982 Kawasaki Gpz 750 tank as I continue to have issues with leftover rust sediment. I cleaned tank but seems there is still stuff left in there. I would like to coat it for piece of mind moving forward.

Saw reviews on Red Kote that were very good. My question is the fuel level gauge inside the tank. Would any type of coating mess up this gauge? It is now working and don't want to mess it up.

Not sure what you mean, but remove the petcock & fuel gauge beforehand. the coating dries to a hard plastic.
I made block-off plates using sheet rubber & 1/4" oak. my bike has a small fuel switch, not the big fuel gauge.
For the fuel filler opening, I used a rubber freeze/compression plug. It has a center bolt w wingnut that you tighten, expanding the plug for a tight fit. no leaks.

I am guessing I should just remove the fuel level sensor and figure out how to seal off all of the holes.

You need to remove all attachments on the tank (petcock, fuel level sensor/gauge, fuel cap, etc) and fashion robust plugs. Before coating you need to remove all the rust. Phosphoric acid is the proper material for this. Home Depot sells Kleenstrip Etch and Prep which is an excellent product to derust the tank. This stuff has phosphoric acid in it which is the stuff the pros use to derust steel in industry. Dump in the gallon and then top up the tank with water and let it sit. This stuff will eat off all the rust in a few hours. You may not even need to coat the tank. Be forewarned though, this material is fairly mild but you don't want to let it sit on the paint nor dry on the paint. Rinse it off with water if you spill.

After all the rust is gone dump out and save the sauce for future use, and then rinse out the tank with lots of water. After you dump out the water follow that with a pint of isopropyl alcohol to help dry out the water. Use compressed air or something like a hair drier to blow dry the inside of the tank. There will be a little flash rust but this won't hurt anything.

At this point you then can decide if you want to coat the tank or not. If so, I have had excellent results with Por-15 tank sealer. Properly coating the tank is a whole different discussion which I'll skip for now. Suffice it to say that doing the job properly takes careful consideration but it's not overly difficult. Do a rush job and you will shoot yourself in the foot so this is to be avoided.

Good luck

What did you use to clean the tank? I have seen a number of options. I tried Evaporust.

Sorry, I added the previous reply before I saw your response. Thanks for the thorough explanation and detail. I kind of rushed through the first cleaning thinking that it would do the trick. Obviously that did not work.

If you succeed in removing all the rust you shouldn't need to coat the tank unless there are pin-hole leaks. Just keep the tank filled with fuel and it should not rust. Ed

Evaporust is good stuff. It's fairly safe to paint and would be a good choice if your tanks paint job is pristine. Only real issue with that stuff is cost. You can get away with one gallon but you should shake and rotate the tank every 10 mins. or so to distribute the sauce all over the inside of the tank. It's slower than the phosphate solution but it should do the job nicely.

If you decide to coat the tank after derusting you should still use some phosphate solution to etch the metal before coating. The Por-15 tank sealer kit comes with a bottle of phosphate solution for just such a reason.

I would resist the coating unless absolutely necessary. Do as suggested and use filters.
Steve

Based on these responses I will probably skip the coating. I just need to do a more thorough job of cleaning and rinsing. I thought I had it the first time but obviously I didn't. Plus add the inline filter.

White vinegar also removes rust from tank & is a cheap alternative
www.google.com/url?sa=t&rct=j&q=&esrc=s&...m=bv.117218890,d.eWE
Pete

Can put chains and sheet metal screws, nuts and bolts, and whatever (best to use ferrous metals so smaller pieces may be later removed with a magnet if necessary) -- just put lots of dry metal stuff inside the dry tank --

Next, wrap the tank with ample cushioning such as bed pillows, blankets, whatever, all tied securely around the tank, leaving no exposed surface of the tank -- just really protect the tank --

And then, put the wrapped tank in your cloths dryer, and run the dryer on no-heat setting for numerous cycles -- keep re-running it over and over.

The "rock polishing" action will thoroughly loosen all rust inside the tank.

When finished with the numerous drying cycles -- 5 or 6 one hour cycles ought to be sufficient for even the most rusted tank interiors -- , empty the tank.

Rinse and re-rinse the tank interior with a soapy dish-water, and rinse some more with fresh water until it's all clean inside.

If desired, can rinse again with a bottle of common household rubbing alcohol, which will help it dry out faster. And can also use a hair dryer.

When dry inside, give it a good douche with WD-40. It should look close to brand new inside.

Fill with fresh clean gasoline, and keep it filled.

Or just ignore all this and use the acid method or other rust dissolver brews or electrolysis. :lol:

Good Fortune!