Bicycle Mechanics - trouble adding air to fork

I have a Marzocchi MX comp fork. I have this problem with all air suspensions to some extent, but with this fork it's really a major pain. When i remove the screw on nozzle after filling it, i lose a lot of the air i just put in. If i go for more air than i want to make up for what i will lose, then i have no idea what the final pressure will be bcause if i try to check the pressue with a gauge i lose a considerable amount just doing that ! I would imagine there has got to be some sort of add-on valve i could get that would eliminate this problem by having a lever release or some such thing instead of having to screw it off leaving too much time for air to release. Is there one, and where can i find it?

there are fork pumps that say they don't lose nay air but i don't own one. I recently got the same fork and have the same trouble. I use a Rockshock pump and all i do is fill it up 20 more psi since it leaks a lot when i unscrew it. Try it out and see how it works.

As i said, that IS how i do it. But it doesn't work because i have no idea what the resulting pressure will be. And i can't check it to see because that itself releases more air.

well this is how i figured it out. When i pumped it up and took it off, it lost some air....when i attach the pump again, the inditcator goes up to where it is.

So therefore, the pressure i pumped it up to - the pressure it is at = how much extra i have to put in it

yea, but it goes down again as i'm attaching it again. Anyway, point is i need to get a pump or valve attachment that will eliminate this hassle.