'98 Voyager fuel cap missing

Hi folks!

I lost my fuel filler cap of my Voyager, and I'm seeking replacement.
The owner's manual says to replace it by original part only because of
possible harm to the emission system from non-chrysler caps.

How is it; are universal caps too tight or too loose; i.e. should they
breathe in or not to let air flow through them, or what's the problem or
possible damage when using them?

I wouldn't mind spending something like 100e for original because I can
get universal at e 8.99,-

p.s. It's been lost for a while, and no problems w/ emissions (just
checked at inspection) so far.

And another question... What's the box underside between driver's seat
and the fuel tank? It's about 15x10 cm's plastic box with one aluminium
and one rubber tube. Just found out that the rubber tube is a litttle
bit loose, but I can't find where it affects. Is it the charcoal
breathing the tank?

 

The check engine lite may be turned on if the evaporative system dectects a
leak, my advise, use the original cap to prevent problems down the road

Glenn Beasley
Chrysler Tech