Tank inner coating issue

[ap73]

Afternoon, I've been reading the boards a long time and finally registered.  I've had the hydro lock issue, and after a lot of work and investigation I believe it due to rust in the tank.  The petcock would occasionally let fuel bypass and sometimes flood the engine.  Oddly enough not consistently.  I rebuilt the carbs and they had a lot of fine red dust in the float bowls.  I think this is rust and was causing both the petcock and the float needles to fail.

So.. I've rebuilt the carbs, new petcock, danmarc fuel cut off and decided to borescope the tank.  It appears to have a grey plastic coating with rust still showing through in a few spots.  Any idea if I evaporust or vinegar soak the tank would it damage that sealant?  I guess my next thing too would be to maybe try an inline fuel filter?

[ridingron]

I have read of several ways to remove rust from tanks. Most of the procedures were for non-coated tanks. Whether or not they would affect the coating, I don't know. Have you looked at you tube?

[ap73]

Ya been researching all night, what a nightmare.  Apparently the previous owner did a tank liner and did it half assed so there are big patches that didn't get coated.  Trying to decide if I should try to dissolve it out or just recoat and hope for the best.  I've got access to large quantities of MEK.

[ap73]

So let it sit full of MEK for 3 days and it didn't dissolve like I'd hoped, but it did break it up into about a million little flakes.  Put 3 feet of chain in the tank and shook it around for a while and then fished out all I could of it.  So the lesson here may be don't use a tank liner unless you prep correctly first.  I'm pretty sure the previous owner just poured it in on top of the old rust.