X Valve goes fullauto

[XM15]

My buddy gave me his Minimag with X valve to fix for him. It was leaking out the barrel and was doing the sprinkler sound air leak when you held the trigger back. I went down one size with the o ring carier and that stopped the barrel leak. I then changed out the little teflon o-ring on the top of the on/off valve pin and that stoped the sprinkler leak. I shot 2 hoppers of paint out of it and every thing was fine. Degased it and put it away. He comes over today and now the thing fires full auto when you barely touch the trigger. If you hold the trigger back it just keeps going full auto too. It only stops firing when you take your finger off the trigger. Any idea's or suggestions on why it is doing this?

[Chronobreak]

so it worked fine when you gave it to him?

and he diddnt emss with it?

not over 800 psi going into the gun? and no sear or on/off mods have been done by you or him?

and nothing has been changed or replaced on the gun?

also is the rear and front screws TIGHT? or the same tightness


welcome to AO

[Geoff Call]

Heh, I'll tell you what works for me. Unscrew the valve halves, and place 2 o-rings in the regulator seat area. One in the back half of the valve where the slot is, and one in the seat itself. Or you can just use one o-ring and put it in the back half of the valve, not in the regulator seat (the gold thingy). It sounds odd but give it a try:)

Here's my valve, I use quads, but you can use the regular stock ones.

[KayleAGD]

Now wait a minute ??. you said x-valve and teflon on/off oring that does not match. please verify what type of parts you have ..

[XM15]

The tank output pressure is set at 750psi. He didn't mess with any mods to it and neither did I. The o-ring I replaced was the small one that fits inside the larger one on the top of the on/off valve. I thought they were made of teflon I must be wrong in any case it is a new one from a automag repair kit. He got the valve like 2 years ago and has had nothing but problems with it mostly in trying to setup the level 10. He also has not used it much in that time so its pretty much new. The sear and the bolt are hardly worn. I have always been able to fix Automags but this thing every time you think its fixed it starts doing some thing else. He has a pro team products 45 double trigger grip frame on the gun also. I don't know if that might have some thing to do with it not working although is worked fine before. Thanks for the help guys

[Cow hunter]

probably has a ULT.... take out a shim or 2 that should fix it....... or the sear is worn a bit...... both cause full auto

[Chronobreak]

you tried tightening the frame screws coorect?

[SpitFire1299]

Do you have an oring on the top of your on/off? Sorry if this is a repeat. You should probley replace that.

[NeoApollo]

It sounds like the on/off pin accidentally got sliced. I had this problem or a similiar problem. I can't remember if it went full auto when I pulled the trigger or when I gassed the marker up, but I'm fairly sure it was after a trigger pull.

This can happen if the pin isn't depressed when you try to take the bolt/valve out. The pin will catch the rail, and (with enough force) snap. It makes sense, because when you're installing a L10 you're removing the bolt/valve quite often. Installing a L10 is how it happened to me. Most of the time it's a pretty clean cut, so it's hard to tell if the pin is it's normal length.

If that's the case, getting a new on/off pin would fix the problem.