Xvalve Tuning Issue - Marker will not fire and I can't depressurize.

[GlassPancakes]

So I attempted to tune my new Lvl10 Xvalve with UL-T this weekend and it didn't go well. I started last week by removing all but 3 of the shims in the UL-T on/off (there were 5 present before I removed 2) and I didn't mess with the Lvl10 at all yet - so the carrier/shim set-up in the Powertube was the same as when I received it. I took it out to the field, gassed it up, and while the sear rod is making full contact with the trigger and the trigger will depress, the valve will not cycle. I would have disassembled to put more shims back in... but since the marker won't cycle, I can't depressurize to work on the valve. I tried running the velocity adjuster in the back all the way in in the hopes it would degas out the back, but nothing. Then I tried running it out all the way, so that it was just hanging on by a thread or two, and nothing there as well. I can't disconnect the quick connect because the valve is still under the full 800psi required to operate the valve. I was trying to fix the half-stroking (is that the right term?) that was happening to my marker under rapid fire - it will sputter and seems like it's not fully cycling if I try to fire quickly.

I've had an Automag for 20 something years now and used a Lvl7 Classic valve for all but the last month or so. I've never run into this problem before and I am freaked the hell out by the idea of trying to disassemble under full pressure. How do I degas the marker so I can work on it safely? Can I take it apart under pressure or will I shoot parts across my apartment in doing so?

Any help is deeply appreciated.

[Walker]

Have you removed the tank?

[WORR13]

ive had this happen and the on/off valve shot into the ceiling, damn lucky it didnt hit me. dont disassemble it, somebody will chime in. possibly try to take the grips off and depress the on/off to fire it?-just a guess

[zinger565]

Only thing I can think of is to remove the tank. Do you have an on/off asa or anything else that would be holding air to the valve? If not, with the tank removed and an open path, screw the velocity adjustment in and out several times, go all the way in if you can. If that doesn't work, you're kind of in a tight spot.

My best advice is to either wait and hope you have a small leak that will drain the pressure, or back the velocity adjustment all the way out with it aiming in a safe direction (pile of pillows/blankets, etc). Do this at your own risk, go slow, you may be able to get pressure to drop without things going kablooey.

[Walker]

He has a thread running over on AO... Tuna and Luke are providing suggestions. He is using an AGD Flatline equipped tank. It is already shut off, but there is no way to release pressure.

They advised him to carefully unscrew a fitting until it started to leak, and then let it sit until the system is purged.

He also plans on putting a ProConnect between the tank and the gun.

[zinger565]

Ah, okay, glad those two are on it.

[rawbutter]

Unscrewing a fitting is definitely the right thing to do in a situation like this.

Air fittings will always leak before the threads let go. Just stop unscrewing the moment you hear it hissing, and everything will degas in a few seconds.

You might damage the threads on the fitting or the valve when you do this since they're not designed to unscrew under pressure, but that can be easily repaired with a 1/8-NPT tap. (They can be bought for less than $10.) Those taps are tapered, so if you go in just one extra turn, you will have fresh metal all around. The threads will all be a little wider, but that only means you'll have to screw in the fitting a little more. Most 1/8-NPT fittings stand proud of the valve, so that's usually not a problem.

[Toestr]

I'd imagine the reason why this is happening is that you have your trigger rod screwed out too far. The on/off pin probably can't move far enough down to get pressure in the dump chamber. Sorry I don't have any better suggestions than what has been given for how to alleviate this issue, but at least you have an idea on how to prevent it.

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[rawbutter]

I'd imagine the reason why this is happening is that you have your trigger rod screwed out too far. The on/off pin probably can't move far enough down to get pressure in the dump chamber.

I had the same thought. The fact that he can't get the gun to fire when he pulls the trigger sounds like the rod isn't long enough. It could also be that his velocity is down too far, since Level 10 bolts won't even cycle if it's too low.