One Rusty Gas Hole

So onto the actual work I've done on the car.

One of the first things I did on the car was to pull out the gas tank to check it for rust. The gas tank in the Sonett is stored similarly to a fuel cell, its under the "swiss-cheese panel" behind the passenger compartment, held in by tensioning straps on the hatch side. I carefully removed those straps and then less carefully removed the gas tank, because holy hell was it jammed in there.

A cursory look into the tank revealed that it was coated inside with a solid layer of rust, not good. Any chunks of rust get in the fuel lines we've got a much bigger issue. So I tried several home remedies to remove the rust from the inside of the tank, an apple-cider vinegar bath, shaking rocks around inside the tank, I even tried my hand at electrolysis and they all worked to a degree. But they didn't work enough for me to be comfortable putting the tank back in the car so I caved and went professional. After some research I ordered a gas-tank restoration kit from KBS Coating for around $80.

The process for the KBS kit takes about 50+ hours depending on how thoroughly you need to treat the tank. The instructions are pretty clear and both the cleaning solution and rust cleaner/etcher both came out of the tank absolutely opaque with the rust they'd pulled off the tank so I'd say it works pretty well. Then of course came the sealant to coat the inside of the tank to cover any remaining rust and I messed this part up. Not severely, but if I did it again I would do it differently.

The kit gives you enough of each compound to supposedly treat up to a 25 gallon tank and the Sonett's tank is actually pretty large for such a small car, about 17 gallons. The cleaner (step 1) is diluted with water and you have plenty to soak each side of the tank, the rust remover/etcher (step 2) however they're pretty skimpy with,you only get 2 quarts and you cant dilute it, the seal (step 3) has the opposite problem though. It just needs a light coating on the walls of the tank, I ended up with too much in my tank and it didn't drain well which results in pooling and then bubbling.

Even with my error the tank was much much better than before the treatments and the seal covered the whole inside of the tank. I sanded off some of uneven paint on the tank which had caused the problem getting the tank out,and repainted it with my rust bonding black paint. We adjusted and installed the new fuel level sensor I'd ordered and then the tank was done.

Before the tank went back in the car I used my air-compressor to blow some WD-40 through the gas line until it came through clear of crud and unobstructed. Then we put the tank back into the car, replaced the fill and vent hoses that had dry-rotted then tightened down the tensioning straps.
Gas tank done.