One of the problems with sorting out petrol tanks is that some of the chemical liners that people did use now run the risk of interacting with the high-level of ethernol in petrol.
A little bit of research on t’Internet and I came across a chemical process. There are some youtube clips and a few alternate suggestions, but you may need some modifications yourself.
Basically, I used :
– a transformer, 12v DC 2.5 amp. Whilst most people use car battery charges it seems, there is a snag. They are getting a bit too intelligent and my Optimate charger knew there wasn’t a battery in the circuit. Something from the model railway or Scaletrix I would suggest as a good choice.
– soda crystals, or soda carbonate. Tesco’s have it (ordered online for home delivery in my case). You’ll need 1kg of crystals for 10l of water, approx.
– a coat hanger, or something similar as the ‘sacrificial anode’; this is where the rust ends up
– a headlight bulb or a meter. I soldered in a 12v headlight bulb to give me an indication of the current passing through the circuit.
– some wire to make the circuit and some clips.
– a plastic cap, off an aerosol can, with a couple of holes in it and poke the anode through it.
Place the positive wire on the sacrificial anode and the negative on the tank, where there is a good connection. Make sure the anode is in the solution, which you’ve poured into the tank, and that it’s not touching the tank itself.
Turn on the circuit and the bulb will initially be quite bright. You will see the solution will effervese and bubble slightly and after a few minutes, the bulb will dim a bit. Within the hour, inspect the anode and you’ll see that there will already be a collection of rust on it. Clean the anode, the bulb will brighten again and repeat.
It’s an impressive process and you keep collecting rust as the process continues. I changed the solution after 24 hours and then repeated again. I’ve order some inline filters, but this should make the petrol tank useable.