Bought a second hand pump for a good deal model PFP-7 which is now discontinued and has no parts diagram available and wondering if anyone could help dealing with an issue i've been having ; the pump will inflate tires but the handle comes up by itself when it builds up pressure and the gauge will only read if i press and hold down ..lose reading when i let go !
So i have been looking online for help , i took it apart multiple times to try and figure out whats going on and everything seems ok without any worn out or missing parts i'm confused , i was also looking if maybe it has an integrated check valve or something that would prevent the air from pushing back on the handle and keeping pressure gauge readings but to no avail - it should be a simple fix right ..well , what do you guys think !?

Sticky check valve? Ask a bike shop to order a rebuild kit.. Or show them what I cannot see in text over the internet..

someone will go find you a video , or you could look for it?








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Have you contacted Park Tools for help? They are very good about supporting their products. Park's web site has a parts diagram and some videos on repairs for the current PFP-8 so that might help with your PFP-7, which has to be similar.

My PFDP-4 came with no repair information or parts list so either Park or their web site is your best approach.

Sounds like the check valve is sticking to me, too. It's usually at the base of the pump, see if you can take things apart and find it. Clean it off with mineral spirits or kerosene, lube it with light oil. You may have to clean out accumulated oily gunk if you or the former owner dripped oil into the pump, that stuff may have dried and accumulated over the years.

Park sells a rebuild kit on their own website that's supposedly fcompatible with the PFP-5 or PFP-7.
And.. Park tool has some documentation.. Have you tried looking thru these various sources?

https://www.parktool.com/product/pro...tabbed-section
and
https://www.parktool.com/product/pum...or-pumps-1096z
and/or
https://www.parktool.com/blog/repair...r-pump-service

Another reason to use presta valves Andy

I found a diagram on the Park site for the PFP-7
https://www.parktool.com/assets/doc/...FP-7_parts.pdf

Look at the bottom of this page fro more "Product Details" including rebuild kits
https://www.parktool.com/product/pro...oor-pump-pfp-7

My reference to the advantage of using presta valves is due to their acting as a check valve. They only open when the pressure outside the valve is greater then that within the valve (barring accidental bumping the valve's "lock nut" of course).

To slightly tangent from the focus on the pump, which I agree is the real issue, here's a little device I was exposed to decades ago and carry in my bike bag. I've had the need to use it more then a few times over those years. It was called a "Damsel in Distress Device". Please excuse the somewhat sexist reference but remember this comes from an entirely different era and what was acceptable terminology then has changed these days. As is easily seen in the photo it's a Schrader valved pump chuck still attached to a few inches of the pump hose. (This one is from a MDI pump, one of the all time good values of yester years). Hose clamped into the free hose end is a presta valve supplied from a bad tube and whose base has been ground down, smooth with the threader portion. The Shrader chuck goes onto the SV that some still ride with and your nice frame pump, set up for PV because that's what your bike has, will attach with no chance of loosing the chuck fittings in the grass at the side of the road (while you swap over to a SV fitting). I have told dozens of riders/customers and a few have made their own. A few of them have thanked me because they helped some SV rider who went out pumpless. Andy

Thanks for all the reply and suggestions ... to answer some ;

- I was not in contact with Park Tool
- I saw they had a rebuild kit but none of which i needed since all my parts were in great shape
- Diagram is discontinued and PFP-8 which replaced my model is not close to being the same if i wanted to compare

I did however taken into account that all the o-rings and rubber parts were greased cleaned them up and re-greased but with less and also took the handle completely apart to do a clean and re-grease of the o-ring and small rubber ball separating the shrader/presta portion in which i suspected might have been part of the culprit since sometimes only one part would blow out air while pumping ...

All n' all with this done it works 50% better now so i'm almost there , sometimes works very best with accurate gauge reading and other times it feels like it sticks when the handle hits the bottom and then springs right back up again by itself !

The Professional version, which is discontinued, has a body which can be disassembled - carefully. There's a flap of rubber that is the check valve. Might be fixed with a swab of grease, and might not. I was able to get the thing apart and put back together (the hose split where it joins the body, and the only way to fix it is to disassemble the whole thing). Not a great design, IMHO. Starting with the fact that the hose is connected so that you can't replace it easily.

But if you are good with your hands, you should be able to get it apart and back together. Careful with the gage needle. Good luck.

Still think the first part of your OP is correct? :-)