My disconnected tank sometimes leaks

[DarrenSV650S]

I've got the tank off the bike and it's lying upside down in the shed. I read on here a few times that you need a vacuum to drain the tank and that no petrol will come out. But mine seems to be leaking
The other night I went in and there was a wee puddle in the upside down tank, and the cardboard underneath was soaked. (so I told it it was a bad tank and not to do it again) So I mopped up the petrol and gave it a shake around to see where it was coming out..........nothing!!!! There was still loads in the tank but nothing more came out

Then I go in tonight and the same thing has happened. So I mopped it all up, then like a couple of minutes later I look and there is another puddle! So I mopped it up again and gave it a shake again .......... nothing again!!!!

Is my tank playing tricks on me?

[Rich]

There isn't actually a decent seal on the filler cap as far as i know, you should have atleast siphoned it out. Bet theres another puddle when you go back and look again.

[Stu]

You should store it RWU
IIRC

being up side down, i'd exspect a leak from the filler cap of some degree

[DarrenSV650S]

No no no its definitely not coming from the filler cap. The puddle was here

[yorkie_chris]

Fuel pump is designed to pump, not seal, try put a bit of fuel hose over the outlet and seal it off.

[DarrenSV650S]

ok cheers