Can anybody help with the AF pump?

My damn pump has quit working.

When I attach a bottle and start to fill it, as soon as pressure starts to build the pump will not pull in any air. On the upstroke, the pump is creating a vacuum and I cant pull it up more than a few inches.

If I take the bottle off, the pump appears to work just fine.

I have taken it apart as far as i dare, I just do not see what is plugging up.


I have looked till my eyes bleed for a drawing on pumps like this, I cant find one. Anything might help.

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when I sent FX an email they replied with

no problem to send it to states just shipping i guess ca 20 euro for kit+stamps i guess airguns of arizona have em cheaper for you paypal is ok”

They have it listed on their sight under FX pricing, but I have not contacted them yet.


I’ve just got the same problem? Have you got yours fixed?

Well so far no luck.

I got the pump unscrewed from the bottom half, and the bottom valve looks almost identical to the Hill. The little pointed plunger has a small o-ring which is in good shape. The valve assemblies are pressed into the inner tube on both ends, so removing them to get to the center rod is near impossible.

Everything I can see looks ok, o-rings not cracked or mashed. Greased up and reassembled but pump just will not work.

I guess Im gonna have to try and drive the valves out of the inner tube somehow. Maybe like knocking delrin bushings off a barrel?

Damn squirrels are outside laughing at me. If they dont stop, I will be bringing out the .17HMR.

Thanks wvanryper,

This is going in the Quick Reference section right now.

Random notes from random sources on pump repair:

BAM pumps:

[Losing air] after bottoming out,and wont pass about 1500 psi, then
the problem is the 3rd stage seal.

Pull the whole thing apart,being very careful not to lose the little rubber BB
in the upper cap(intake valve)(There’s a bigger one in the base,but it seems
to stay put)Clean it all out,and radius and debur the entry to the 3rd
stage(innnermost) tube.Also lightly radius all edges of the o-ring groove on
the 3rd stage pump.

Get some icemaker 1/4″ nylon tube,put about an inch on a 3/16″ drill bit in your
drill(or lathe)on the shank(smooth part)and cut some rings just a little
narrower than the o-ring groove,while spinning,with a sharp hobby knife.
While they’re still on the drill,cut each one across at about 45 degrees.These
are your piston rings.The ID is a little small,so put a couple wraps of glide
dental floss in the groove to keep you piston ring centered.

Install and reassemble.This seems to get around the problem of the 3rd stage
o-ring wearing and getting cut.It may take a couple tries to get the packing
and width just right,but mine is now easily hitting 3000 psi,10 fills and still

Axsor Gen 1 pumps:

Theres an article in the Airgun Letter by Tom Gaylord on maintaining the
pump. You unscrew the base from the tube, (unscrew the rectangular piece
from the pump tube) Then dump all of the ball bearings onto a rag then rinse
in degreaser and dish detergent then dry real well and remove all oxidation.
Wipe the internals of the rectangular bottom pump piece with air chamber
lube(for spring guns) then when the balls are dry then dump back into
the pump and put a few maybe 3 or 5 drops of the air chamber lube then put
the pump back together(twist the tube back onto the rectangular piece then
shake the pump to distrubute the lube on all of the balls, then plug the hole
where your air comes out of to fill your gun and pump to 3000 then quickly
unscrew the bleed screw to let all the air out and do this 2 to 5 times. Then
your pump is good as new, even better than new.

Use RWS air chamber lube and do not use anything else. Only about 3 to 4
bucks or less for a small bottle of this needed air chamber lube. Do this about
every 3 months to 6 months.Depending on humidity and dampness where you
live. Less if dry and no humidity.

Axsor Gen 2 and early FX pumps:

Remove the bottom black body from the tube, on the bottom of the tube
assembly is a porbe that goes down into the glass beads, remove the probe,
inside the bottom of the tube assembly is a bullet shaped valve , be careful the
valve is closed by a small spring and the valve will fly out if you are not
watching, on the valve is an oring that you need to replace. I was unable to
find the correct size oring locally so I actually used one that was a little
oversized but it seems to be holding up well.

Newer FX pumps:

The FX is easy to disassemble I have cleaned the FX pump twice and replaced
the check valve O ring twice. If your pump is leaking down under pressure it
could be a bad check valve O ring. If the handle wants to rise at the bottom of
the stroke and you can see the gage dropping check the valve. You can
separate the pump from the block with two adjustable wrenches one wrench to
hold the block the other for the nut at the base of the pump tube. After the
pump tube is separated from the block you will see a brass nozzle you will
need a pair of water pump pliers and a little duct tape to protect the brass
from the pliers teeth. Wrap the brass with tape with a firm grip on the pliers
unscrew the nozzle you will find a spring in the nozzle and the valve in the
base of the pump tube. Check the O ring for a cut or debris I think I used a
#005 Viton as a replacement all of the other O rings in the pump were fine.

Reassemble in reverse order screw the pump body back into place slowly
listening for a crunching sound if you hear it shake the block to move the
desiccant balls away from the nozzle to avoid breaking them.

Also re: recent FX pumps:

The FX can also be rebuilt but with more difficulty due to the lack of hex
shaped parts especially around the check valve. The FX check valve is located
inside a cone shaped piece that requires the fabrication of a special tool to
unscrew it or you could go the old vise grip route to unscrew it. The FX uses
desiccant balls(glass) in its base that will crush if careful attention is not paid
during reassembly and they need to be washed and dried if you reuse them.
The HILL has hex shaped parts or a set of flats on the critical parts and the
filter is a one piece porous tube that is replaced with each service and nothing
will crush during reassembly.

Apologies to the original authors.


FX pump diagram:

Yep thats the same drawings I found.

I googled Hill Pump and found some site, dont remember the name, had to register to open the support pages.

What king of crazy SOB drew those, downright confusing, but interesting none the less….


Where did you find the pump drawing?

quote SilentS:

Riff I took my air force pump apart. I unscrewed the bottom off the pump. At the end of the pump is a nut. Unscrew the nut and there is a spring and small brass cone with an o-ring. I replaced the o-ring because it was to big and the valve would get stuck. I put it back together and it worked for awhile Hope this helps.

Thanks for that info SilentS.

I found the bottom half very hard to remove, I havent been able to turn if off there yet. Im sure its somewhere in the bottom half, everything on the top part is in good condition.

I found internal drawings of a Hill pump. It looks similar to the AF, but at least I can see how it works now. Getting it apart is another thing.

the same happened to mine I just pumped it a couple of times without the tank and some times it started to worked but I realized that using it like it said in the af dvd is the only way I don’t get problems just make shure to get the full extent in both bottom a up pump and hold it for a second I noticed that when I didn’t puled it up all the way it like dobble pumped and became very hard to move try it out and see if it works and do the stroke in a single sweep.

Riff…….. off topic from your post….but man, you’ve got some damn funny stories. 😆 😆


Riff I took my air force pump apart. I unscrewed the bottom off the pump. At the end of the pump is a nut. Unscrew the nut and there is a spring and small brass cone with an o-ring. I replaced the o-ring because it was to big and the valve would get stuck. I put it back together and it worked for awhile Hope this helps.

Yep, they know it is junk and try anything to get out of replacing them, actually if it came apart on it’s own it is defective and not out of warranty…

A question that typically get’s stuff done is, “Can I have the name and contact information of your attorney? I’d like to have my attorney send him a letter so we can resolve this…”

Like Target has a no return policy, well sure if you don’t have any balls, talk to a manager and you will get an instant refund!!! 😆

Bummer on the tank filling stuff…

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