Here's what I did. (originally posted last December.)
I was heading to the Orphans Home Christmas car show to buy my first trophy for the "new" Suburban. It quit on me about 2 miles from the house.
I determined it had trash in the fuel tank that had blocked the fuel filter. The fuel pump has a settlement bowl before the fuel filter and it, too was full of trash.
I drained and pulled the tank. I added some pea gravel and mineral spirits to it, sealed it off and strapped it to the tractor wheel. I brought the tractor in the shop, jacked it up and tumbled it about 30 minutes, then unstrapped it and turned it a quarter turn and gave it another 30 minutes.
I then washed it out with a heavy duty cleaner, like Simple Green but a cheaper brand I can't remember the name of. It took a couple of rinses to get all the gravel out.
I let it air dry a day and a half then poured about a quart of phosphoric acid in. I left that in about 30 minutes, sloshing and turning every 5 minutes or so. Then I dumped it in the gravel. I thought later, "Dummy, you could have saved that and used it to de-rust small parts later."
I rinsed with water a couple of times again. Then I ran a hair dryer in it for 30 minutes. Next I added a pint of acetone and sloshed it around. It is supposed to absorb any remaining water. I dumped that and gave it another pint. After dumping the second pint I let it air dry. I thought about the hair dryer again but was afraid the heat coil might ignite the fumes. Then I thought about compressed air but that would be blowing moisture back into it. By the time I got all those thoughts out of my head, the acetone had evaporated. Even if there was any left in the corners, it is soluble in the Red-Kote. That or MEK are the recommended thinners for it. Mine didn't need thinned.
Next I poured in 2 quarts of Red-Kote. I sealed it off and rolled the tank around a while to be sure it covered all surfaces. There is a big baffle in the burb tank and I wanted to make sure it got covered too.
I drained about a quart and a half back out. It left a thin coat of sealer in there. I thought about a second coat but I really don't think this tank needs it. It was really in pretty good shape after I got all the trash and surface rust out of it.
