To

Have a look at this item from Frost who sell POR 15 and other cleaners and the like.

www.frost.co.uk/frost-tank-strip-liquid-1-litre/.

I haven't used it myself but if I were to, I would advocate putting some metal "shrapnel" (magnetic nuts and bolts and washers with) it to help the process.

If you have time to waste use brass/ Stainless Steel shrapnel as an alternative!!!

Oh, and count them all in and count them all out whichever you use.

Why do we have these tank issues, and at a cost?

Anglo American racing fuel (E0) appears to be one answer, again, at a cost,

Fuel was fine until just before 2006, so why mess with it?

Me thinks it's best to take the liner out, clean the tank inside and don't  put contaminated petrol in there.. Sorted.

I got my 1963 steel tank professionally refinished and painted in 2010. When I purchased the Electra in 2004 there was about half a gallon of very stale fuel in it, from the previous century . E0 I guess.

Caswell seemed, at that time , to have the best claims and I chose their 2 part liner product. Not the cheapest. Didn't try checking the tank for petrol leaks. Seemed stupid thing to do after all that money spent on paint job. Just sharp nuts and bolts as described above for rust removal. Then follow instructions being careful to coat every internal surface and not spill any on the new paint.

Never had to strip out a tank liner. Caswell do a tank lining remover.

14 years later and with regular use, sometimes on E10 by necessity, the lining looks sound, and the thin corroded tank bottom is hanging on well with the extra support.

Cheaper tank lining materials are available,  but why would you?

Peter