Hand Pump backing up while under pressure

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orion

orion

Member
Jan 18, 2019
1,458
437
FL, United States
Hi guys,

Just posting in case any of you have more experience than me. My hand pump is not working properly, when I go in the up stroke I feel is not catching air and I feel pressure going up also, like if something is not sealing properly. I've some things but I'll wait for the responses to validate my assumptions...

Any help will be appreciated,

Thanks
 
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Mine was doing the same thing last week. The problem on mine was a small o-ring that was blown in the base where the tube screws in. Replaced it and it works like new again. Mine actually has 2 o-rings in that area the larger one shown and a small one in the center that was blown.
 
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Scotty

I think this is going to be the issue, I have the rubber ball on the kit but I couldn't find the ball on the pump the first time I took it apart

Orion,

Wish I knew something about posting videos, but Coby Leo, of TOPA Manufacturing Company, who make most of these pumps, has a 2-part video showing disassembly and re-assembly. He states a high percentage of problems occur with dirt/debris in check valve at pump base. Check it out on YouTube, simple fix. Best of Luck, WM
Click to expand...


I have watched all those videos and I have cleaned the check valve. I think it's the rubber ball that scotty mentioned before. I'll give that a try now.. 
 
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Orion,

It's the middle picture, "One-Way Clearance," that Scotty shows, where I think the problem lies. Unscrew the brass plug, clean out, then re-install cleaned parts. Make sure to only screw brass plug even with housing, not further. Cleaning out the pump base isn't a bad idea, but the one-way valve is more susceptible to dirt/debris. WM
 
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update:

My pump doesn't use that rubber ball, it's on the kit but the part where the rubber ball is supposed to be doesn't have a hole.

I cleaned well the one way valve but I was having the same issue, I completely disassembled the pump and the rod that move up and down that creates the pressure was really dirty, the end of the rod communicates with the one way valve on the other side. I cleaned all the gunk and I think the pump is working better.

I think I'll be ordering one of the Hill pumps eventually.

Thanks everyone for the help
 
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Orion,

My Chinese handpump worked fine on Umarex Gauntlet, but got way too hot, despite pump 40, 15-minute break, repeat, routine, when filling FXs. Finally, a small O ring blew out of the brass fitting right up the handle. Dismantled, only to find no coolant had been installed. Repaired, re-filled with mineral oil, now OK. Seller credited $10 but I'm a Yong Henger now. Found the same black gunk inside the "inner" high pressure tube, reminded me of used truck grease, think that stuff eventually messes up one-way valve. Wish you best of luck with yours, WM 
 
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