As I pump up the tire, the gauge does not hold its reading. Almost immediately the pointer returns to zero. Any suggestions will be appreciated. I have presta valves.

That's what happens when your tire is not holding air.

If your tire is filling up with air, then -- and I'm just going out on a limb here -- I would guess that the gauge is broken.

I bought a Lezyne pump a few years ago and I tried and tried to like that pump but I just don't. I went and got a Serfas pump at the LBS for half the cost and it works much better IMO. Sorry, not exactly helpful for your situation.

I have a Lezyne floor pump - love it!

Do you have a screw on chuck or press on? Regardless, it is possible you are not getting a good seal onto the valve stem, or you have a slow leak in one of the connections between the valve stem and the body of the pump.

​​​​​​My screw on chuck has a pressure release button on its side. This pressure relief button allows me to unscrew the chuck more easily than it would be if there was 100 psi in the hose.

​​​​​​If you are able to put good pressure into your tire, you have a leak somewhere between the chuck and the pump body - that would include a leak at the gauge.

I have a screw on chuck. I have the older version without the pressure release button.

I got a Lezyne steel drive floor pump with the screw on presta chuck, tried it, then returned for a refund. Turns out Blackburn honored the warranty on on older pump when I requested to purchase new rubber gaskets, they sent me a new Core Pro floor pump with a lever grabbing chuck that works like a charm. Love it.

I think that the problem is in the chuck. When I tighten down it sometimes alleviates the problem. My question. How do I replace the o-ring in the chuck, and what size would I need?

Wouldn't this all be easier if you just contacted Lezyne instead of going fishing here? They have a website, you know.

Floor pump parts: https://ride.lezyne.com/collections/...ps-accessories
Customer support: https://support.lezyne.com/hc/en-us
Contact: https://ride.lezyne.com/pages/contact

I had the same symptom with my lezyne floor pump. They sell a replacement gauge kit, which I bought, but that didn't solve the problem. Next I bought their replacement 0-ring kit. But that didn't solve the problem either. So I then bought a replacement pump head. And that still didn't solve the problem. So now I have the most expensive floor pump ever that doesn't work.
And I now use some cheap ass Joe Blow pump that works perfectly.

I did, I am waiting for them to reply.

I'm still curious to know if you are able to inflate the tire. Sorry if you've answered that previously. But it does sounds like if you attach the chuck properly, the pump and gauge work fine. Is that correct? If that's right, you found the source of your problem.

Its not unusual for an O-ring to wear out after hundreds of times pushing it on and off the stem.

The problem I see from looking at my Lezyne Flip-Chuck, I can't see an easy way to remove the O-ring on the Presta side of the chuck. (My chuck is reversible.). If you have the same kind of chuck, you may have to use something like a dental pick or sewing needle to pull out the worn O-ring.

If it is gonna take a while for you to hear back from Lezyne, or its going to cost a ridiculous amount of money for a 45 cent O-ring, you could take the O-ring to your local Ace Hardware store (not a Home Depot type store) and match it up. O-rings come in standard industry sizes and it is pretty rare for a company to have a special mold made for a proprietary O-ring size.

This may sound a bit unsanitary, but whenever I put a pump chuck on a valve stem, I always lubricate the stem first with a handy lubricant I always have with me - spit.
​​​ This helps keep the O-ring from wearing out when it's pushed past the screw threads on the valve stem. But it will eventually wear out. Thanks to you, I now know how to change it!

My guess is that Lezyne will come through for you and send you the O-rings you need gratis.

I do not know how to replace the o-ring. Also what size is required.

I am having difficulty with my new Lezyne pump. Screw on chuck to Presta valves.

Pump is almost brand new.

Pressure makes it difficult to pump. Gauge registers dramatically high with any pump action and no air is actually going into tire. Seems to work better on tires that are low or almost empty.

Any help would be appreciated. Have sent a message to Lezyne tech support provided above. May take a while to get a response.

Thanks

WaveyGravey, it sound like you need to 'burp' your presta valve. The tiny rubber seal inside the valve stem often gets 'seated,' gets sort of stuck in place. Before you put the chuck on, press the valve in and let some air out of the tire.

Oh...and remember to unscrew the little brass nut on the valve first, too. These are the two most common issues that cause the problem you describe. One or the other of these happen to me about once a week. I say, ' what the heck...? Oh, I forgot to...'

I recently had an opportunity to use my Lezyne pump. It is an older model (no gauge) and slimmer (I guess not the newer high volume option). It was, of course, the rear tire on my new road bike with disc brakes and a through axle. A staple with both arms in the tire - well, at least, it was clearly visible. Getting the tire off was no fun but getting it back on was hell.

Back to the pump: It took quite a bit of playing to get it screwed on the presta valve and a lot of effort to inflate the tube/tire. Lots of pumping just to see some inflation and then grunting force to get the tire up to very firm - changing my body position often to get better leverage/angle. The only gauge I used was fingers squeezing the tire to approximate the inflation I get at home with a floor pump where I know the pressure is 80-85. Repair on the road is just not that easy.

Somewhat off-topic. I had with me a useless tire tool but one I've liked. It is expandable and and one end clips to the quick release axle and the other end slips into the bead and you rotate it around the tire while the other part rotates around the quick release and it peels off the tire, like using a few tire irons. Anybody know of one that might work similarly with a through-axle wheel?

Daniell, yeah. I hear ya. During this discussion I looked inside my own reversible chuck and can see the O-ring in there starting to get chewed up, too. I've been using this pump for over 8 years, so that's not too surprising. But since this chuck is holding air fine, I'm not gonna mess with it still it starts giving me trouble.

If you've given up trying to use this chuck as is (though it sounded as if you CAN get to seal fine if you fiddle with it), you have nothing to lose by picking the O-rings out and taking them to your local Ace Store. No guarantee they will have it, but if that's your only choice other than waiting for Leyzne, it worth a shot.

Unless you get the O-ring from Leyzne (a sure path, though it might take a while), you are not going to know what size to get unless you get the O-ring out of the chuck. O-rings are designated by dash numbers. It's probably something like a dash 008, or something similarly tiny.

If you find one, don't use the needle to put it in. Maybe with something like a Q-tip with the fuzzy end cut off you'd be able to push it in and seat it in its groove. Don't forget lubricate it. A tiny bit of silicone lubricant will work, but don't use any petroleum product. Most people don't have silicone lubricant, so maybe water, or good 'ole spit will work in a pinch.

I can't help you with your Lezyne pump but when it finally gives up the ghost, buy a Silca floor pump. The base model is all you'll need. It will be the last pump you'll ever have to buy.

No need to buy the worlds most expensive pump, geez.

I have a friend whos had his Lezyne Classic Drive for years and it works just fine. Another sturdy built option is the Specialized Air tool Pro. Having said all of that, Lezyne carries spare parts to fully restore your pump.

Have been in touch with Tech Support at Lezyne. They are sending me some parts to remedy the situation. But the pump is brand new.

Also, will try burping the valve initially when pumping tires. That may work.

If I buy another pump, probably would take the Silca recommendation or probably the Specialized.

With the Lezyne thought I was buying the last pump I would ever need. But seems to big of a pain to use.

Thanks!!

If you know it’s always 20 psi low, what’s the problem?

I bought a Birzman MAHA Apologee II, or some such name because it got very high reviews, anyway I too thought it would be the last pump I would ever buy, nope, the darn thread on air chuck is junk. I had a problem with it shortly after I got it where it would refuse to put air into a Schrader valve, and it would unscrew the screw in ring on the chuck whenever I would try pumping a Presta, so they sent me a new updated chuck under warranty, that one developed the same problem, so they sent me another saying the new one was improved, though I couldn't see anything that would tell me it was updated yup it was improved, it lasted 2 years instead of 5 months! I'm hoping to keep limping it along for another year. Then I noticed today that Birzman came out with yet another air chuck, I might try ordering the newer air chuck and see how well it works but according to a video I watched about the new chuck it seems to be no different than the one I got on how it operates, I don't know.

How do you know the Lezyne is not the correct one? Maybe all the others are inaccurate.

What I can't figure out is why the hell do they no longer make those gauges so that a person can adjust it to make it accurate? I had a 50 year old Silca that could that, but none, not even the new Silca can be adjusted anymore. In fact from what I remember all floor pumps back then you could adjust the gauge accuracy by turning a screw either on the underside of the gauge or by twisting off the top glass part and the screw was right there next to the needle. This screw would adjust the spring and had marks of + and - so you knew which way to turn it. It is a spring, those things can change PSI readout from atmospheric changes to wear over time just as your bathroom scale will do. I did google check to see if any one made a gauge that can do that or if there were any way you can adjust one these days, nothing, I got nothing. We live in a throw away world, of course that is better for the environment and natural resources, so you either have to buy a new pump if the gauge goes bad or if that particular company makes a replacement gauge, or say screw it and use a separate handheld gauge.