Curious ??
Cant be rocket science!!
I did buy a geniune new correct cap to replace the original cap which was working its way loose between refills.
The newish one now 4 months old now also works its way loose.
is someone going to tell me there are heaps of threads on this ?? I did a quick search :tired

I feel weird posting this ,this is my 20th car.
was there meant to be an updated instruction manual with this cap other than whats in the log book LOL

PS. at times (when near empty), a "fume" NOT "fuel "smell evident but no worse than its been since 2004 till now

would you consider buying a lockable cap if one is available ?

The "turn until it clicks" type of cap seals really well and can't loosen, but if you look at the design, if one of the clicky bits breaks off, it is impossible to tighten enough.
Have a look.

PS Wreckers generally take them off the car and chuck them in the boot. Have a scrounge and pick up a few in good condition, carry a spare one in the car and check the cap you are using every time you refill. Works for me.

I think Mitsu used the same cap on every model since about 1985, so should be plenty about. lol

why not , sounds like i am setting a safe combo at the moment as it is !

Couple of quick (and cheap) things to check...(In order)

1) Do you get a notable air rush sound when you open your fuel cap, after disposing of say 1/2 tank in one hit? (If not, you may have a vacuum problem, proceed to 2)
2) Is the rubber ring on your fuel cap OK? (small smear of Vaseline on it to ensure seal, or replace seal)
3) Is the vacuum tube going to the fuel fume canister (under the bonnet son!) split? (replace if so)
4) Is the above tube still pulling a decent vacuum when engine is running? (If no, replace and re-check)
5) Is the fuel filler seat (where cap goes on) or neck split or cracked? (Use a torch, not a match!)
6) Is the fuel fume canister split or have a breach where vac lines go in, or at mounting ring? (Can happen if driving on rough dirt roads etc)

All of the above can cause your issue..