just thought i iwould share my experience with you.
On my '67 mk2 sceptre, i kept getting clogged fuel lines. I cleared them with an airline each time ,but in the end i had to investigate.
I removed the tank and on blowing it out with an airline , i notice loads of flakes of paint coming out. I also found a fibreglass repair on the bottom. i realised i would never be able to confidently get 100% of the paint out, so i decided to split it.
I ground off the fibreglass around the bottom to reveal 2 very small pinholes, 1 either side. There was a small patch which had started to pit and this is where the pinholes were.
Then i cut it in half along the seam.
this is what i discovered


so i vapour blasted the insides........

and my welder Andy is half way through welding it back up.

as you can see in the last picture we have put 2 patches over the worst areas. the bottom one is fully tig welded the top one not done yet.
obviously i will have to pressure test it before i refit it to the car ,but it is looking good.
i will keep you posted on the results.
cheers
David