Pump Stuck

[Blackthunder]

I have a Bull pump. The pump pumps until gets to but 80 bar and then it becomes incredibly hard on the upstroke, It pretty much seizes.



When I let the air out, I can start over until it once again seizes at about 80 bar.



I did service the pump with an original service kit. It stopped pumping normally, and I discovered that the most inner o-ring had come off its brass shoe and was damaged. So, I replaced this most inner o-ring.



Does anyone have any idea of what might be going on here?

 

[Blackthunder]

This is be the pump in question: https://www.aliexpress.com/item/Folding-model-BULL-pcp-hand-pump-high-pressure-3-Stage-max-300-bar-factory-outlet-not/32432003104.html?spm=2114.11010108.06001.7.650c649bqRxbhh&gps-id=pcJustForYou&scm=1007.13562.109986.0&scm_id=1007.13562.109986.0&scm-url=1007.13562.109986.0&pvid=3e7c986e-6aaa-411a-af4b-0e5ca73638b7



Maybe I should a compressor after all..........



I am really starting to get tired of hand pumps and their moodiness.

 

[airgunfans]

Given their simple construction, its quite safe to say that the only things that can fail are the O rings. May be one of them started failing to seal at 80 bars so the compressed air does not go to the outlet but stays in one of the cylinders causing an air lock ? I will pull it apart again and examine all the O rings. If nothing can be found, just replace all of them. Check all the O ring seats, remove any burrs with fine file, relube thoroughly. It should work again. Dont forget to check the check valve which is close to the outlet, there is an Oring there too

 

[Blackthunder]

Thank you for your reply. I did actually replace all o-rings with an original kit.

I mailed Bull and they told me that it was the inner piston: https://www.aliexpress.com/store/product/BULL-high-pressure-pcp-hand-pump-fittings-3rd-piston/1229091_32854328745.html?spm=2114.12010615.8148356.1.10cb3405Cc8eCj

This seems like an updated version of the part.



I have been using this pump for a few years now, and this is really the first issue.

 

[airgunfans]

That piston has two parts. The one with a green O ring and a spring is the check valve I have mentioned. I believe you have replaced that O ring already. The other part has got a dark brown colored plastic seal, while you are waiting, you may try replacing that seal. The metal part can hardly fail

 

[Blackthunder]

I did actually change the o-ring and the hard plastic bits. The pump started having problems, so I took it apart again, the shoe on the inner part had come loose, so I changed the o-ring and applied some medium strength loctite to the thread.



But now there is this problem. I will place an order for this new updated piston and also for an Altaros Booster .