So whats best for cleaning the inside of a fuel tank?

Will be unbolting the tank soon and it needs a good clean.

Have seen vinegar mentioned, anyone tried it?

Thanks

washed gravel, water. Then some acid, I use brick cleaner. Then rinse and some phosphoric acid (cheap coke)

other methods available.

Depends how rusty it is. If its just a light clean as above.

If its filthy thick rust I'd cut it open, wire brush it, then weld it shut. However cutting open any fuel tank comes with a government health warning...

Can't see on OP if tank is ally, steel or galvanised. I looked into this while doing an old Mini steel tank with small corrosion inside. POR15 do a tank clean/seal system. It expensive, but cheaper than new tank. Not sure if it would work on alloy tank, need to check website. If cutting welding, seriously recommend flushing with lots of water first.

old steel tank.

Trying to sort garage for it, so as soon as i can will get it moved, unbolt tank and take pics.

Or if i can find someone to do a copy in alloy...................(i like the bling)

Personally I'd rather buy an alloy tank and avoid the corrosion issues - may be lighter as well.

JAF Fabrication did my new tank in ally to my drawings. Highly recommended!