I am having a hard time setting up this shock right. When I ride it a bit then reconnect the pump, sometimes it has lost pressure, but sometimes it has actually gained!

Is there something funny going on with different air chambers? And the Debonair sleeve? Are they all equalized when the shock is uncompressed or does it have to be cycled to equalize? If so how hard?

Or maybe my shock pump gauge is just broken..?

Shock pump is not a good test. When you connect the pump, air from the shock enters the shock barrel. This slightly depressurises the shock as pressured equalise.

Is your sag changing?

Debonair – generally equalise a few times during the pressurising. Disconnect the pump and compress, you’ll hear it ‘pop’.

Debonair as two ‘extra’ chambers the Postive side is charged as you pump up the can but the Negative need the shock to be cycled (bounced) to become charged. As above, do this as you pump up the shock, never heard mine pop TBH, but have seen the pressure go down after being cycled.
As above, you pressurise the pump everytime you connect it, and so loose pressure from your shock – do not become mistaken your loosing pressure due to that…

Why do you have to disconnect the pump to compress? (assuming the valve is clear of frame or rocker which in my case it is)

I don’t… no idea why you’d need to, as far as I know (well guess) you just allowing the negative air chamber ‘port’ to come open and become pressurised, so what the shock pump being connected has to do with that.. I’ve no idea

Why do you have to disconnect the pump to compress?

My shock pump is rated at 350psi.

My Debonair is rated to 350psi and I run it at 275psi.

If I fully compress a shock at is, at 275psi uncompressed, the pressure will be way above that at which the pump is rated. You are not relying on the shock seals which are designed for the pressure spike, but could well be overloading the pump gauge.

Ok, fairy muff.
I’m running a 400 psi (beto) pump, as I’m running above 300psi… no issue yet!