Keg generates its own CO2

No, seriously...

I've got a keg on tap right now that hasn't been on gas for days, yet keeps pouring. I took it off gas because it was way over-pressure and was pouring nothing but foam. A few pours later and it was reasonable...

So I never put it back on gas and just drew another pint and it's WAY over pressure again. I should probably mention that this keg was "force carbed" - that is not sugar primed.

So can one of the smart kegging guys explain to me what's happening? How is this thing generating its own pressure?

Andy

PS - the beer tastes fine so there's no cidery infection symptoms that might create CO2.

Did you pull the pressure release after taking it off of gas? Could be just residual pressure in the keg.

How long was it in primary/secondary before being kegged? Maybe fermentation wasn't done or was stuck, and the racking to keg stirred up the yeast and restarted fermentation.

If it's overcarbed, it's got a huge reserve of gas. When you pour a pint, the headspace pressure drops a little and the beer offgasses a little CO2. It will keep doing that until you start noticing less and less carbonation.