190e varnish in fuel tank

[kmaher01]

Any tips for removing? Picture attached. Fuel tank sat for 10 years with about 10l in it, now has this varnish / sediment build up in it. Considering acetone as seeing that a lot on YouTube but unsure when it comes to the plastic parts in there.

Any tips? Thanks. Pic 1 is from the sensor hole, rest are down the neck.

 

[peterws1957]

I think I'd be removing the tank and then filling with a solution of citric acid and leaving for 24 hours, rinsing and repeating if necessary. Citric granules are cheap and I use 1 part to 6 parts of water. Dissolves rust and other stuff and does not affect plastic. Used in cooking etc so you can tip down the drain safely. I'm sure there are commercial products available though. You might want to consider replacing the tank though.