FX full air dump

Happens when the pressure is too low. That's what happened to one of mine. Count your shots so you don't go below a certain pressure level guessing 1500 psi just guessing maybe 1400-1600 psi. You have to fill to 200 bar count your shots see when it dumps all the air and next time STOP and refill BEFORE that few more shots. Yo!
 
Maybe you have a leak so your start pressure already was sitting below that FULL ON AIR DUMP DO NOT PASS GO line and the valve was shut till you fired that first round to do that FULL on air dump. Just always REFILL EVERYTIME BEFORE FIRING YOUR FIRST SHOT after being left alone even for few hours. YOU GOT HIT WITH DREADED FULL ON AIR TANTRUM DUMP BABY! Yo!
 
I have yet to try to fill it.

Loaned my SCBA tank to a friend. Could try to hand pump.....

HAND PUMP FROM ZERO ZIP ZILCH EMPTY NOWT NIX NIL NAUGHT NOTHING NADA BUPKIS AIR? You may not be able to pump fast enough to get that valve to seal even if you cock it. If that is the case you will have to plug your barrel with some lubed felt cleaning pellets to keep that valve forced shut as with other PCPs that are IMPOSSIBLE to pump up when their reservoir or bottle is totally empty. You assume the risk if you don't have cleaning pellets and decide to double and triple load pellets to get it done instead but that will work too and just point it in a safe direction when pumping till you fire them all out. Good Luck. Yo!
 
Did you cock it and quick hard bursts while banging with a rubber mallet? Keep trying and if not THEN the other way to close that valve is to load lubed felt cleaning patches into that breech then continue quick hard bursts and rubber mallet like playing an instrument. If that still does not do it then you will need to disassemble and replace the valve seal. PM SENT