Tuning FX Impact Loss of Power

[Frank4889]

Good day all,

I have an issue with my FX Impact Mk2 Power Plenum. 

I have tuned it numerous times using all the techniques available. I can get it to were it is extremely stable with very low fps and sd, The thing is the gun will shoot well that day but if you let it sit for a while it will loose power. for example the other day a tuned it at 883 fps. a couple of days later I checked it and after around 20 shots of shooting low it settled at around 873 fps. I didn't mind it re zeroed my scope and left it there, the next day I went to shoot gun was at 840 fps and wouldn't go up. This happens every time. I retune the gun and it does it again. it is unusable at the moment because oft this. I hace check the C1 and C3 all ar tight, I have used three different regs one being a HUma and two of them oem FX impact regs.New valve rod and valve housing. I have changed the the gauges and all are accurate. there are no leaks or reg creep. At this point I have no idea as to what else I can check. 

Any help will be appreciated. 

 

[2fast2furious]

There are 2 reason i can think of.

C1 backing out a little after each shot. You said you checked it but its kinda impossible to tell if it back out or not.

Hammer wheel set screw. Its the tiny hex screw left of the hammer wheel backing out. That will also effect fps.

 

[triggertreat]

With you extensive knowledge, all I can think of is the gotchas like the hammer adjustment screw turning back out on you as you shoot it, which can happen. Maybe mark where it is with something like Liquid paper or whatever you can come up with to see if is turning/moving.

 

[cahil_2]

Mine was doing the exact same thing and it was the c1 slowly unscrewing. Screwed it back in with lock tite. No problem since. 

 

[dannya1a]

I would guess its the HST screw. I used vc-3 Vibra tite to get it set and locked where you want it to be. you can readjust with it if need be and don't need heat to break it back free. works great at keeping my HST screw where I set it.

 

[FX-USA]

Good day all,

I have an issue with my FX Impact Mk2 Power Plenum. 

I have tuned it numerous times using all the techniques available. I can get it to were it is extremely stable with very low fps and sd, The thing is the gun will shoot well that day but if you let it sit for a while it will loose power. for example the other day a tuned it at 883 fps. a couple of days later I checked it and after around 20 shots of shooting low it settled at around 873 fps. I didn't mind it re zeroed my scope and left it there, the next day I went to shoot gun was at 840 fps and wouldn't go up. This happens every time. I retune the gun and it does it again. it is unusable at the moment because oft this. I hace check the C1 and C3 all ar tight, I have used three different regs one being a HUma and two of them oem FX impact regs.New valve rod and valve housing. I have changed the the gauges and all are accurate. there are no leaks or reg creep. At this point I have no idea as to what else I can check. 

Any help will be appreciated.

Hi Frank, 

We’re sorry to hear you’re having some difficulties with your rifle. Please call or email our customer service Monday - Friday 9 am - 4pm EST if you have not resolved the issue, we would like to help get your Airgun up and running, possibly figure out if you need any warranty repairs. 


Regards, 

FX Airguns USA

E-mail: [email protected]

Phone: (866) 639-0772

 

[Frank4889]

Thank you all very much for your help. Will check the C1 and C3 as well as the hammer screw again. 
Will reach out to FX USA for help aswell. 


Thank you. 

 

[Frank4889]

Could a bad Oring say C39 cause this. A friend told me it could but if it was bad i should see a leak or reg creep or something. Just thinking outloud. 

 

[Frank4889]

I have Loctite on it, will mark it with liquid paper just to make sure. Im pretty sure this all started when I installed my power plenum a few months back. Just remembered, I can only hear the power plenum fill every other shot. it will fill on one shot but not the next. every time.