Without looking into it I dont know but probably yes, plastics for chemical storage are often fluorinated to protect them.

UPVC chemical resistance is ok but some mild attack

www.spilltech.com/wcsstore/SpillTechUSCatalogAssetStore/Attachment/documents/ccg/CBOOM.pdf

If the joints are done with a general commercial grade (Crap) adhesive with low PVC content it could be something leaching out of that.

If you have any rubber seals this is a high probability of being the issue as at best the rubber used is generally neoprene or lower natural rubber both of which are going to give grief as NBR (Nitrile) or viton should be used.

kite killer said..

elmo said..
If the joints are done with a general commercial grade (Crap) adhesive with low PVC content it could be something leaching out of that.

Yer im starting to think it could be that.
This is what i used.

www.bunnings.com.au/protek-250ml-type-p-green-solvent-cement_p3140034

God knows what toxins have leached out

From my memories as a kid, a kero heater is often not the nicest smelling appliance, so toxins from pvc cement may not be such a big deal.