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Just replaced a bad inner tube with a new, Presta valve tube. Unfortunately, I seem to be unable to get any air in the tube; I hear air leaving the pump and not going anywhere.

I tried investigating the usual suspects:

  1. The pump is not sealed on tightly enough: Doubtful; several times I was able to lock the pump head so far down on the valve that it took considerable effort to remove it again.

  2. The nut on the valve was closed: Nope. Opened and closed the valve several times, pushed down on the valve enough to hear a minuscule hiss of air. The valve is open.

  3. Wrong pump type: Nope. Managed to inflate my other Presta valve tire just fine.

The only thing I can think of is that the complete lack of air pressure in the tube means there is nothing closing the valve, so the pump has nothing to depress and the sealing nut sits on the air opening. However, that sounds wrong to me.

Any ideas?

A.H.
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  • Is the old tube presta also? Using the same pump, can you get air into the old tube? If you can, this proves that there is no problem with the pump – PeteH Feb 03 '16 at 19:54
  • There are pumps with a 'dual' head for presta and other valves, and sometimes their mechanism to switch between the heads fails resulting in air coming out of the wrong head. But I guess you would have noticed that since you checked everything else so that's probably not it - thought it was worth mentioning for future visitors maybe. – stijn Feb 03 '16 at 20:52
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    Does it have a separate valve core? If so, did you try tightening the core? – mkpaa Feb 03 '16 at 21:30
  • It's unclear what you're describing. If you hear air going into the tire as you pump, and it does not come whooshing out when you pull the chuck off, then presumably the pump is OK. (Hardly any pumps depend on the Presta valve to prevent air from flowing back into the pump anymore.) Did you perhaps hole the tube while installing it?? – Daniel R Hicks Feb 03 '16 at 21:55
  • Thank you guys for the input. The old tube was also Presta, and I was able to get air in just fine, so "bad pump" is out. My particular pump doesn't have a "switching" mechanism, it has two air ports: one for Schrader, one for Presta. The air leaving the pump doesn't sound like it is going into the tube and leaking out, but if I can't get the tire working checking for leaks is a good idea. – A.H. Feb 04 '16 at 18:12
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    @stijn I have this issue routinely with new tubes. For some reason my stand pump doesn't push air through the presta side. When this happens, I inflate the tube just a bit with my mouth. After that it works normally. – jcbrou Feb 04 '16 at 18:27
  • @stijn - The easy way to deal with dualhead pumps which have that problem is normally to put your thumb over the other hole. – Batman Feb 04 '16 at 22:43
  • Rotate the wheel so the valve is in a different position? – shoover Feb 04 '16 at 23:33

3 Answers3

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Perhaps its obvious, but maybe the tube has a leak? Is it an old tube that has perished and is just letting air out as fast as you pump it in?

Perhaps try taking the tube off the wheel, put it in a bucket/tub of water, and then pump. Can you see bubbles somewhere?

brendan
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    Excellent point - even brand new unused tubes can have punctures, which is why you test them before trusting them as your "spare" – Criggie Feb 04 '16 at 05:53
  • The inner tube was fresh out of the box, but I may need to try this. – A.H. Feb 04 '16 at 18:12
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    You should always slightly inflate a tube before inserting it into a tire. This helps assure that it doesn't get twisted or pinched during installation. – Daniel R Hicks Feb 05 '16 at 03:31
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If you hear air leaving the pump and it is not going in the tire then you don't have a seal. If you have a seal and valve is blocked then you would not hear air leaving the pumpt

paparazzo
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A presta valve on some brands have removable valve cores. If the pump is good, and the tube is not punctured, then there are 2 more options:

  1. The removable core is not seated properly, and needs to be tightened with a valve core tool.

  2. The valve core is bad/leaking, and should be replaced. If it is removable, replace the core only. If it is a one piece valve, replace the tube.

presta valve with removable core and descriptions

zenbike
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    The valve core doesn't appear to be removable (I may be wrong), but I didn't know this about Presta valves. Thanks. – A.H. Feb 04 '16 at 18:22
  • Not all of them appear as obvious as the one in the photo. Check the threaded section below the valve tip. If there are 2 flat sections on this threaded area (you can just see them by the top red arrow above) then it unscrews. If the threads go all the way around with no flats, then it does not. – zenbike Feb 06 '16 at 00:13