December 14, 2014 at 11:31 pm #18340
I got a new Fx pump 4 stages, but it does not work because there is a strong force that pulls the handle down and after a few strokes this force is so strong it is impossible to lift up the handle.
It feels like there is a spring of ever increasing force that pulls down.
I believe that a broken valve does not let air flow from one cylinder to the next.
Also I live in Uruguay and shipping the pump for repair is complex for re-importing it and costs.
My question is: anyone knows if this may be fixed by myself with a rebuild kit?December 14, 2014 at 11:39 pm #215301genetParticipant
The pump is made to work in both directions. I can’t tell how much force you’re experiencing, but some force is normal, and it dissipates if you make sure you hold the plunger in the ‘up’ position for a second at the end of each stroke. You might try closing the valve on the handle and see if it becomes easier.
If you think your pump needs service, you can probably get better answers by calling FX or an FX vendor.
GsTDecember 15, 2014 at 3:33 am #215312
Yes thanks,quote GeneT:
Force increases for each stroke. After 15 strokes (reaching a pressure of about 10 bar) the force is so strong that it is impossible to move the handle either upwards or downwards, until you discharge pressure with the purging valve.quote GeneT:
fact is I wrote an email to fx some time ago for another issue and they never replied. This is why I am asking here. But I understand this is a complex issue and probably nobody can reply. In any case many thanks again.December 15, 2014 at 5:39 am #215317AnonymousInactive
The primary O-ring seal needs replacing, this is the smallest one that does the main work and is located deep inside the pump. It’s a tricky pump to take apart, I did mines 2 times in the past 2 years or so.
AOA sells the REBUILD KIT FOR 4-STAGE PUMP $30.00 O-ring kit.
Most people get stuck on this step.
~ GKUDecember 16, 2014 at 10:14 pm #215418bogmanParticipant
My FX 4-stage had the same problem; it seems to be an issue, even with new pumps. Get a diagram to help understand the design before you start taking things apart. Make sure only a pure silicone grease is used as a lube. The last pump I got (replacement) also had your symptoms. However, I powered/forced the issue and eventually it started working normally. So, you might try to force the pump a bit and see if it loosens up. Keep the pump cool; don’t use it if the body gets hot.
FX customer support never replied to any communications from me, so don’t be surprised if they ignore you.
Get a Hill pump, when you can; it’s a much better design, especially for reliability and moisture removal.December 30, 2014 at 12:18 pm #216269quote GKU:
Many thanks, the seller is sending me a rebuild kit free of charge as a warranty. I should be receiving it in a few days. Even if I am really worried at the idea of doing the job.quote bogman:
I tried to force it and got some results, even if unreliable:
If I uplift the handle very fast, the downwards force stops, even if sometimes I have to try it 2 or 3 or more times. So this way I was able to charge, for the first time, my Benjamin pistol. However, it seems that as the pressure rises, it gets more unreliable and have to uplift the handle many times to have it stay up. At the end, at the maximum pressure, there was no way to have the handle stay up.
Also, maximum pressure was 3000 psi for the pistol gauge, but only 2000 psi for the pump gauge. This is no small difference, so wonder which gauge is broken.
Finally I noted that when the handle does not stay up, it is en error to push it down because the downwards force of the next uplifting gets much stronger. So when the handle does not stay up I have to try again and again to fast uplift it, resisting the temptation to push it down.quote bogman:
Yes Bogman, I have choosen a FX only because a couple of persons confirmed that the pumping force is a bit lower for the FX even if more pumping is required to have the job done. I am low weight and even with the FX I have to put all my weight on the handle to reach the maximum pressure. I would be unable to do more that that, unless, perhaps, charging me with a backpack full of bottles of water. :rofl: Well, the good side is that it is a nice physical exercise, I really like it. 😀December 31, 2014 at 7:54 am #216316AnonymousInactive
That happens to my other pumps as well and it’s the main pressure O-ring that’s causing the problem. Changed it and it’s good as new again. Secondly it could be the value needs cleaning and or replacing.
And again, most people get stuck on this step.
Take your time on the rebuild because of the extra stage it’s a little harder to do.
You will need this if you don’t have it already.
“Also, maximum pressure was 3000 psi for the pistol gauge, but only 2000 psi for the pump gauge. This is no small difference, so wonder which gauge is broken.”
Maybe neither is broken but I would trust the gauge on the gun. All of my PCP airguns are very close in the readings on both gauges. Except my Air Force airguns the gauges on the pump reads 300-400 psi lower then the gauge on the gun. To be safe I’d fill to the gauge on the gun and take that as the true pressure reading. If this happens on another brand of airgun I would think that the gauge on the pump maybe bad.
~ GKUJanuary 12, 2015 at 3:39 pm #217081madmunkiParticipant
My FX pump (new from aoa) makes a ton of racket when I first start pumping. Sounds like springs bouncing around inside. Once pressure gets up to 1800 psi, it quiets down and sounds like it should.
It works, so I guess its normal.
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