Clean a Poly Fuel Tank?

[Apollis]

Hope I'm in the right place.
I have an unmolested and rusted out 84 CJ7 . Its been sitting over 10yrs now with fuel in the tank and its definitely bad. I just got the body off frame and was surprised to find that the tank was a poly one. I figured it was a metal tank and planned on just scrapping it. Since its a poly tank without rust in it, can it be cleaned of the old shellac with something and reused? or just trash it like I planned and get a new one. How do I know what size tank it is? I believe that there were 16 and 21 gal available.

 

[hole]

With the body off it should be easy enough to do. Pull the sending unit out and you'll get a good idea how bad it is in there. I acquired an old boat years ago that had fiberglass tanks with old fuel gelled up like rocks at the bottom, so I used a high pressure nozzle on a garden hose to break it all up, then my shop vac to suck it all out. It took me 7-8 hours of fill and suck it out over and over, but in the end I got all the crud out. Do take care to make sure you get all the water out when your done though

 

[Apollis]

I was thinking. remove the tank and use the pressure washer. Don't see what it could hurt at this point. If I can save a $100 not buying a tank, its worth a try. I'll know just how bad it is when I get it off there. I've been able to smell it since I pulled the tank filler hose.
Any clue how to tell what size it is?

 

[Torxhead]

The later CJ factory tanks were 15 gal. steel and 20 gal. poly. The aftermarket versions could vary. I would suggest doing it the old fashoned way if you can't find any i.d. on it anywhere.

 

[PaRenegade]

The factory 15.5 gal tanks were metal and have a rounded under look to them from the back. An aftermarket poly replacement is available for these and very worthwhile getting.
The factory 21 gal was a poly tank and has an angled rear bottom, and is wider as viewed from the back.

If the stuff inside is hardened and not gel like, take a short length of chain and throw inside. Shake and roll that all over, dump it out, then take some dishwashing liquid and hot water and slosh that around to wash it out. Then rinse with clean water and let set in the sun to dry out.

 

[Apollis]

Yep, poly tank with angled bottom..I like the chain idea.

Thanks

 

[Hedgehog]

I did this before coating a set of old H-D tanks

- Remove all the floating around in the tank.

- Use a hose or something similar to flush out as much crud as possible.

- Dump in a couple gallons of muriatic acid acid and fill it with water

- Let it sit for a day, dump it in a safe place, a lime rich soil will neutralize it, it's relatively easily handled pool acid guys.

- If it isn't clean do it again, you might add a little or acid. Remember fuel is carbon based and muriatic acid will remove it without harming the poly.

 

[huntingbigun]

Yep, poly tank with angled bottom..I like the chain idea.

Thanks

I just replaced my 20 gal tank due to the strap being overtorque by the PO, once you unscrew the fuel tank sending unit you can see inside very easy and be able to clean it, they do not make the OEM tank anymore and the replacement 20 gal aftermarket tank will require different mounting and skid plate as your should have full skid plate the looks kind of like pot and the tank is strapped inside then the complete assy bolted up to the frame.


The P/N of the tank which is molded on top is J536 2498, there are other P/N from trucks and etc that will fit, got mine off Ebay and you can buy the fuel gage sending unit that has the pickup and new screen cheap.

 

[gutthans]

Found an old poly tank like yours...didn't have acid so I poured in a gallon of old Carb Cleaner and let it sit for a day AFTER I used a chain inside and framing hammer to whack the outside....

Turned out it was a Wrangler tank after all so I bought the factory sending unit rubber gasket and used it for a template to fab an aluminum cover to mount a CJ sender/pickup tube in. Put a hatch in the rear floor to access the setup in case of fail. Installs just like the CJ metal tank units.