The message
from Al Deveron contains these words:

Advice please... I need to stick a plastic fuel tap into the hole in
the bottom of a plastic 2-stroke fuel tank (the tank looks like
polypropelene) on an outboard motor.

I've a feeling they're polyethelene, but neither is amenable to gluing.
You can weld them with hot air and a filler but it's not easy.

--
Skipweasel
Pay no attention to that man behind the curtain.