So after determining with your help that I can use a regular old 66-67 B-body fuel lever sender in my wagon, I want to drop the tank and get a new sender in there. I'm going to need to clean it out though - I have some fine rusty sediment that comes and goes floating around and slowly piling up in my fuel filter (or in last week's case, in my fuel bowls - don't use Autozone Duralast fuel filters!!)

The thing isn't sending very threatening amounts of rust up the line, but I want to neutralize whatever is in there. I think whatever is in there is mostly settled at the bottom of the tank since it seems to appear right after I fill up or after a lot of city driving (lots of jostling about in the tank). It's never clogged a filter on me, but it has gotten a good tablespoon of sparkly rusty silt in there in there over the course of a few tanks.

What combo would be best for a mildly dirty/sedimenty tank? Hose blast + Simple Green/acetone + phosphoric acid? I'm wary of some coatings - POR-15's sounds good, others sound like they need to have perfectly clean and etched metals or else they flake off and cause more problems than the original rust did.

I know the usual answer for initial cleaning is "have it boiled out at a radiator shop" but I've been unable to find any actual radiator shops in my area, just places that have "radiator" in their name but don't do anything other than installs and Jiffy Lube flush-and-fill junk. Though if anybody knows of a good place around Snohomish county, let me know...

POR15 isn't the right product for the inside of the tank. And if you have no radiator shops, look at a different market- motorcycle or vintage snowmobile markets. They'll be able to help you out with guidance, products, and maintenance.

I used the POR gas tank kit in my 65.That was probally 15 years ago at least.Still looks new inside and it was real funky.I followed the instructions and after using the sealer let it sit in the sun for 2 days to dry.Its better than a new tank.I also used there chassis paint on the outside before I put it in place.Rocky

Id drain the tank. Put about a gallon of diesel fuel in it along with a length of chain. Shake the snot out of it. Flush it real well and after the inside has dried put some of the Harley SDD tank sealant in it..

I power washed mine and glad I did, because it revealed a series of pinholes at the lowest part of the tank that would have otherwise leaked soon. I patched them with a two part epoxy/sealant and then undercoated the exterior of the tank and that lasted for about 4 years before it started staining the tank from new leak(s) at the same locations. Probably not the best repair approach but it worked on a budget back then.

por15 makes a biodegradable cleaner you can toss in it and let sit for a while.
I tried other stuff like muraic acid(pool supply store) but it was just nasty to get rid of.

there used to be a couple of rad shops in bremerton. but has been 15 years since I was there last.
there is one just on the way out south to tacoma.

The most economical seems to be Prep and Etch by Kleen Strip. You can get it in Home Depot for about $15 a Gallon.

I started doing the tank on my 56 dodge with this stuff. You can see in the pic below where I have treated 2/3 of the outside. I painted it on with a brush and left it wet for a few hours. Then wiped it off with a paper towel. The Prep and etch will leave a phosphorus coating so you dont get flash rusting when its done.
I was then going to treat the inside using a sealer from Eastwood or POR.



I never got to do the inside because I decided to go with EFI and did not want to take a chance on fouling a very expensive fuel system. I ended up going with Moyer's Gas-Tank-Renu. http://www.gas-tank.com/
They did a great job and the turnaroud time was about 2 weeks. I highly recommend them.

When I first bought my Cuda it had a tank full of gas that had been sitting in it for about 4 years, needless to say it was a nasty smelly mess. After draining the tank it had a bunch of rust in it. I took it to a radiator shop and they boiled it clean and coated it with some material. I still get a little bit of rust in the fuel filter but not much.

I don't remember the cost because it was over 10 years ago but around $100 comes to mind. Honestly if I had to do it all over again I would just buy a new tank and be done with it.

Either way, I bring this up just to give you another option to consider.

Best of luck with the tank clean up.

Not to be 'that guy' who doesn't answer your question- but I got a brand new tank from rockauto (.com) for around $150. It fit perfectly and I don't worry about it ever. I sprung for new straps and J bolts which GREATLY simplified the install. Mine was a 72 a-body, dont know if your tank is as cheap or available or if you want the original for some reason.

When I work on bikes I always put in a few cups of diesel and a couple of handfuls of loose hardware. After a couple times shaking and draining it comes out pretty clean.