FX FX M3 blows through both regulators to full bottle pressure in plenum.

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far_shot

far_shot

Member
Jan 21, 2018
370
25
Ia, United States
Gun was working fine and then, after sitting for a few weeks, full bottle pressure was reading at the 1st and 2nd stage gauges. Swapped gauges. No change. Rebuilt the second stage reg (all 0rings). No change Rebuilt the 1st reg (all 0rings) No change. For history, have only adjusted the 2nd reg down with all air bled out and have never touched first regulator till now. Currently, I screw on 200 bar bottle and first reg stops at 100 bar and second reg at 60 bar. Great....... After about 2 minutes, suddenly the 1st reg climbs to 200 bar in 10 seconds or so and second reg follows and goes to 200 bar. Do I need new regulator pistons? Weird because I usually have no problems in working on all my FX rifles (6) with the Panthera never needing any attention :)
 
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How high have you ever set the regs? We had this problem on a couple FX regs after being set too high a single time. But I would suspect your reg piston or sealing surface has failed. For my time and money I would upgrade to new regs either Huma or replace with stock updated brass piston FX regs. (Assuming you have the older plastic style pistons.)
 
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1st reg was factory setting, second reg has never been set above 100 bar. Just took it apart again and both pistons are 16 mm (plastic). Bagnall and Kirkwood has the brass pistons..... or the complete regulators. Huma-Air has the M3 First Stage Tuning Regulator that adds 23 mm to the bottle connection. Not sure on shipping to the US...I think it's quite a bit tho :(
Just seems odd that it takes a while to creep up a bit and then suddenly goes straight to bottle pressure on both regs.
 
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I just did it last night, the MK2 was sitting for couple months and when I started shooting I noticed it was creeping...

Use a jewellery lupe, you won't see with naked eye but there is an indent in half.

20240616_120759.jpg


Remove the indent with 1000->2000 sandpaper and next step mirror polish the Reg pistons, 40-20-10-5-1 micron pollishing pad/cloth is a best.

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Also, most people replace all the Reg orings, some easier (NBR70) and some need a lot of patience (NBR90), but
don't forget to replace the oring in the action block as well ;)
 
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<<Utah airguns sells the brass pistons>>
I think I'll go with complete regulators so I don't have to deal with replacing those tiny ID bore 0rings again.
Do you run your washer stacks dry or lubed. I have smeared a light coat of silicone grease on them, dry and just silicone spray on other guns. Doesn't seem to make any difference once they settle in.......... ¯\_(ツ)_/¯
 
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**Remove the indent with 1000->2000 sandpaper **
I chucked up the second reg piston and used a wet stone to remove "most" of the dent as square as possible and then polished. Surgically cleaned. It made the 16.02 mm piston shorter to 15.98 mm. Results are the same....still blows thru it after first reg goes ballistic. Not sure how the dent arrived, but I do leave all my PCP guns fully charged when parked. None of them have gave me any trouble as far as regulator pistons, but it seams I often get a new leak after I degas them to fix a leak in another area. I'm guessing the 0ring relaxes and then won't seal after the pressure is put back on them. Most of the time, the new leak is an 0ring that has hardened or taken a set :(
 
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Seems like I gave you outdated advice, Huma used to make more regs for the Impacts including a stock pressure front reg. I cant find it for sale anywhere now. So I suppose your options are to replace the front with a stock reg from Utah Air and the rear with either a stock or Huma. I would call Utah tomorrow and see what they suggest.
 
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