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Odd Observation About New Floor Pump, or Have I Been Doing It Wrong All These Years?

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Odd Observation About New Floor Pump, or Have I Been Doing It Wrong All These Years?

Old 07-26-12, 09:45 PM
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MegaTom
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Odd Observation About New Floor Pump, or Have I Been Doing It Wrong All These Years?



I got a new Lezyne CNC Floordrive, and it's pretty nifty as far as air pumps go... The thing is, neither chuck (it came with two, a twist-on one and a 'speed' chuck) will hold the tube's valve open unless I first drop the PSI significantly. In other words: it's impossible to "top off" my tires, I must deflate and then re-inflate. What gives? Possibly a side effect due to their ABS feature?
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Old 07-26-12, 09:50 PM
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try pressing the valve for a moment before pumping up the tires. i had a similar issue where i thought i needed to completely deflate my tire to get my lezyne to work but it turned out that the tube just needed a little warm up.
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Old 07-26-12, 09:53 PM
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Many gage equipped pumps require the piping to be filled to get a reading. My suspension pump achieves that via the first pump, then holds it open but the tire pumps can be the other way since having to force air through a schraeder valve that isn't pre-pushed can be quite a bit harder. The amount of air required should be minimal, though. When this happens on your unit does it result in any losses around the fitting or pump or is it just filling the plumbing?
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Old 07-26-12, 09:58 PM
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Originally Posted by aquateen View Post
try pressing the valve for a moment before pumping up the tires. i had a similar issue where i thought i needed to completely deflate my tire to get my lezyne to work but it turned out that the tube just needed a little warm up.
I already do this as part of my routine, it has no effect in this case.

Originally Posted by mtbikerinpa View Post
Many gage equipped pumps require the piping to be filled to get a reading. My suspension pump achieves that via the first pump, then holds it open but the tire pumps can be the other way since having to force air through a schraeder valve that isn't pre-pushed can be quite a bit harder. The amount of air required should be minimal, though. When this happens on your unit does it result in any losses around the fitting or pump or is it just filling the plumbing?
No air is being lost, nor is it filling any plumbing. It is staying in the tube as the valve is not being held open at all while the chuck is connected.

--Edit--

P.s. When I say "tube" I mean the one inside the tire, not the hose from the pump.

Last edited by MegaTom; 07-26-12 at 10:02 PM.
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Old 07-26-12, 10:11 PM
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Both tubes?

Maybe the valves are a bit sticky and the pump is having a hard time overcoming the stiction+pressure? Try a quick drop/spray of lube inside the valve core and see if that helps.

Another thought is that the valve inside the pump itself is sticking somehow. I've never torn one of those pumps down but DO have a lot of experience servicing both Park and SKS pumps and have seen this before. With the Park pumps there were problems with the gauges themselves that created a similar situation. We had to swap the gauges out. With SKS I don't remember having this particular problem. Those pumps are serviceable and it was mostly about replacing seals and such.

I do love a good head scratcher, though.
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Old 07-26-12, 10:17 PM
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Originally Posted by Bob Dopolina View Post
Both tubes?

Maybe the valves are a bit sticky and the pump is having a hard time overcoming the stiction+pressure? Try a quick drop/spray of lube inside the valve core and see if that helps.

Another thought is that the valve inside the pump itself is sticking somehow. I've never torn one of those pumps down but DO have a lot of experience servicing both Park and SKS pumps and have seen this before. With the Park pumps there were problems with the gauges themselves that created a similar situation. We had to swap the gauges out. With SKS I don't remember having this particular problem. Those pumps are serviceable and it was mostly about replacing seals and such.

I do love a good head scratcher, though.

FOUR tubes. All the same Specialized brand though, with the threading from top to bottom. I will put some lube on there and maybe try a another tube if I have a different kind laying around. But for some reason though, I can't get this ABS thing out of my head, based on how it seems to work, I can see how it may be causing the problem.
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Old 07-26-12, 10:34 PM
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Odd, I have the exact same pump and Specialized tubes. I just twist them open, screw it on, and pump. I usually push the top down for a moment before I put it on, but I don't need to with this pump to get it started. I'd guess it's either a problem with the specific pump or user error.
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Old 07-26-12, 11:40 PM
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Burp the Presta valve, screw on the Lezyne chuck, then use the piston of the Lezyne to kind of force the Presta valve open. Kind of like gradually lowering the piston until pressure is encountered, then push straight down a little bit harder on the piston as if forcing something open. This should result in your pump gauge needle going straight to read the pressure in the Presta tube.

I am not very articulate with my explanation, but I hope you can catch my drift. Try that and report back.
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Old 07-27-12, 12:24 AM
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Are you twisting the cap open on the presta valve?
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Old 07-27-12, 12:56 AM
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When the air doesn't go into the tube, I assume you still pump right? Sometimes you've gotta pump the hose up past the PSI of what's in the tire before it opens the valve. On my pump this happens maybe once a month, and is usually because I didn't get the pumphead on the valve quite right. Still works fine tho once I get past the initial difficult pump.

If you're seeing readings of 120-140psi on your pump and air still isn't going in, then I guess you do have something funky going on.
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Old 07-27-12, 02:28 AM
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[QUOTE=jmX;14533354] Sometimes you've gotta pump the hose up past the PSI of what's in the tire before it opens the valve.QUOTE]

Yes, this is the phenomenon I was trying to articulate in my previous post.
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Old 07-27-12, 06:11 AM
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I have found the same thing. For the speed chuck to get a good seal, I have to deflate the tire first.

I've pretty much ditched the speed chuck and just screw the other head onto the valve stem. But that only works with non-replaceable valve core stems. I find that it will unscrew the valve core otherwise.
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Old 07-27-12, 06:52 AM
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Originally Posted by Jed19 View Post
Burp the Presta valve, screw on the Lezyne chuck, then use the piston of the Lezyne to kind of force the Presta valve open. Kind of like gradually lowering the piston until pressure is encountered, then push straight down a little bit harder on the piston as if forcing something open. This should result in your pump gauge needle going straight to read the pressure in the Presta tube.

I am not very articulate with my explanation, but I hope you can catch my drift. Try that and report back.

Originally Posted by jmX View Post
When the air doesn't go into the tube, I assume you still pump right? Sometimes you've gotta pump the hose up past the PSI of what's in the tire before it opens the valve. On my pump this happens maybe once a month, and is usually because I didn't get the pumphead on the valve quite right. Still works fine tho once I get past the initial difficult pump.

If you're seeing readings of 120-140psi on your pump and air still isn't going in, then I guess you do have something funky going on.
Understood, and no, I actually did not try doing this.... it never really occurred to me to pump air into a closed valve, but it does make sense now that I think of it.
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Old 07-27-12, 08:04 AM
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I recently had a problem with my Joe Blow universal push on nozzle. I couldn't get the nozzle on my presta valves. So I took the nozzle apart and removed the spring...like a ball point pen spring..and the little slug inside the nozzle that depresses the presta valve open and acts as a check valve with each handle push of the pump..
Good and bad news now.
Good news is...Joe Blow nozzle always pushes right on and the spring and internal slug no longer interfere with the presta valve sticking up.
Bad news is...sometimes when pumping the tire the presta valve doesn't push down and open. Per the other advice given, if I pre burp the presta valve, no problem. Once nozzle pressure exceeds tire pressure, the valve opens and the tire fills provided I burp the valve.

Lastly, I read/learned on here a while back of guy(s) removing their pump nozzle and just pushing the hose over a presta valve. This no doubt would abrade the ID of the hose over time but apparently works. By me removing the check slug inside the nozzle I have effectively done this to my nozzle...making it only an attachment of the hose and no longer a check valve.

My guess OP is your Spesh tube presta valves are sticky by nature as nozzle pressure should overcome the valves. I believe sagging tire pressure is the same thing as reducing valve stickiness. Try a couple of short burps without sagging all the tube pressure down which is too much work.

Last edited by Campag4life; 07-27-12 at 08:08 AM.
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Old 07-27-12, 08:08 AM
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This happens with my Lezyne all the time. Not that I have to empty the tube, but often I'll find that the pressure goes up to 140 on the pump so obviously it's not pumping the tire. It's a pain to remove the nozzle, bleed some more air out and then start over, but that's all it takes. Typically if I bleed it one or two pushes worth it will pump up first time. The result is that the beginning pressure in the tube is somewhere in the 60-80 psi range.
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Old 07-27-12, 08:13 AM
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^^^^ interesting. It would seem to be an quirk of this particular pump?
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Old 07-27-12, 09:04 AM
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Originally Posted by Bob Dopolina View Post
^^^^ interesting. It would seem to be an quirk of this particular pump?
Only thing I can think of and why I posted is...the Leyzne pump must not have a spring and slug to push down on the presta valve to open it.
This makes the nozzle more sensitive to depressing the presta valve down because it relies solely on air pressure from the hose.
Only way to know this would be either to disassemble it or...find an exploded view of the Leyzne nozzle on the web.

Other thing OP...and what I considered with my Joe Blow pump not being a fan of a universal nozzle because I believe functionality is compromised serving both Schrader and Presta valves is...purchase a Presta specific nozzle for your Leyzne pump. This would likely resolve the issue.
The question is...who makes the best Presta specific nozzles out there?...and is best a thread on or push on style nozzle?...former would be problematic for example with smooth stem Presta valves.

Last edited by Campag4life; 07-27-12 at 09:09 AM.
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Old 07-27-12, 09:14 AM
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Try not tightening the air chuck so tightly. I read this in the other pump thread a few days ago, tried it yesterday and it worked. I've only tried it once so it might not be the solution.
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Old 07-27-12, 10:28 AM
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Originally Posted by jmX View Post
When the air doesn't go into the tube, I assume you still pump right? Sometimes you've gotta pump the hose up past the PSI of what's in the tire before it opens the valve. On my pump this happens maybe once a month, and is usually because I didn't get the pumphead on the valve quite right. Still works fine tho once I get past the initial difficult pump.
I have this issue pretty regularly (maybe 1/3 of the time) when inflating Specialized brand tubes...I think that's what the OP said he was using, as well..
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Old 07-27-12, 10:40 AM
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Same thing happens with my Topeak Joe Blow pump. It doesn't matter the brand of tubes - happens on my commuter, road bike, mountain bike, wife's bike, etc. All different tubes.

As was suggested, I just release some air before inflating and that usually does the trick.
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Old 07-27-12, 11:06 AM
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Originally Posted by GP View Post
Try not tightening the air chuck so tightly. I read this in the other pump thread a few days ago, tried it yesterday and it worked. I've only tried it once so it might not be the solution.
I agree this might help. The chuck head only needs to seal just past the top threaded section of the presta stem (past where the plastic cap threads on). I believe the Silca chuck has a rubber grommet/o-ring that seals there, and the Lezyne should too. A bare hose will work if it seals up until the desired pressure or the pressure strong enough to blow the hose off, whichever is lower. For the Lezyne chuck, I screw it in only far enough that there is resistance to light turning force; screwing it on further is pushing it on farther than needed and can abrade the chuck's o-ring on threaded valve stems.

The presta valve is held closed by simple physics: when the inner tube pressure is higher than the outside pressure. So unless the valve is sticky, air should go in when the pressure in the pump hose is greater than the tube pressure. Burping the valve once or twice can help loosen a sticky valve.
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Old 07-27-12, 11:07 AM
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Originally Posted by Bob Dopolina View Post
^^^^ interesting. It would seem to be an quirk of this particular pump?
Yes, it is a quirk of this particular pump.

The air chuck is quite shallow and uses a small rubber gasket to attach to the valve head. It does not have any lever. You simply slide it on and pull it off. It is similar to Silca's pump heads, but much smaller and made of cheap plastic.
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Old 07-27-12, 03:53 PM
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OK, home from work and I played with the pump some more.

Firstly, for those who do not own a newer Lezyne pump.... on these chucks there really are no internals to speak of other than the rubber gasket. There is no lever on the outside, and there is nothing on the inside that holds the pin down, to keep the tube's valve open. This is the same for both the twist-on chuck and the quick-release chuck (which is merely a plastic attachment that screws on to the end of the metal twist-on chuck. It seems that air pressure alone performs this function, which also seems to be how the "ABS" (Air Bleed System, a bleeder valve on the metal chuck) works.... when you press the bleeder valve, pressure is released from the hose and the now positive pressure from the tube forces the tube's valve shut.

I tried the above trick of pumping air onto the closed tube valve to hopefully push it down & open, and this does work to an extent. I still have to first let air out of the tube, but not nearly as much as I previously had to. Somewhere around 60-80 PSI seems to be the sweet spot where I am able to push open the valve that way. If I leave any more air in the tube I am unable to get the valve to open on its own at any reasonable pressure (I gave up @ 140 PSI in the hose).
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Old 07-27-12, 04:14 PM
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Originally Posted by MegaTom View Post
OK, home from work and I played with the pump some more.

Firstly, for those who do not own a newer Lezyne pump.... on these chucks there really are no internals to speak of other than the rubber gasket. There is no lever on the outside, and there is nothing on the inside that holds the pin down, to keep the tube's valve open. This is the same for both the twist-on chuck and the quick-release chuck (which is merely a plastic attachment that screws on to the end of the metal twist-on chuck. It seems that air pressure alone performs this function, which also seems to be how the "ABS" (Air Bleed System, a bleeder valve on the metal chuck) works.... when you press the bleeder valve, pressure is released from the hose and the now positive pressure from the tube forces the tube's valve shut.

I tried the above trick of pumping air onto the closed tube valve to hopefully push it down & open, and this does work to an extent. I still have to first let air out of the tube, but not nearly as much as I previously had to. Somewhere around 60-80 PSI seems to be the sweet spot where I am able to push open the valve that way. If I leave any more air in the tube I am unable to get the valve to open on its own at any reasonable pressure (I gave up @ 140 PSI in the hose).
As discussed, a stock Joe Blow has a spring and small piston to push down the Presta valve...and I removed mine because the piston would jam with the Presta valve upon insertion. So now my Joe Blow nozzle is the same as the Leyzne nozzle...no internal parts...except the Joe Blow has a lever to exert lateral force on the stem which I like. The percusive wave of air should push the valve open and a guess is the Specialized valves must be a bit sticky.
Good luck.
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