Presta valve difficulties.
 

So just installed new tubes on my bike but the center part of the valve just gets pushed down and let's all the air out whenever I try to inflate. Wondering if there's a way to fix this or just buy a new one.

Is the pump head you are using correct? as in, is it set for a Schrader valve not Presta?

Do a you tube search on how to inflate a tube with a presta valve...not rocket science...but you do have to learn how they work...

Like he said, it's not difficult, but you need to know how it works.

Make sure that you're using a pump made for presta valves. Many floor pumps have chucks with two holes in them - one for Schrader, one for Presta. Other pumps have removable/changable parts in the chuck - one configuration for Presta, another for Schrader. Check your pump instructions or post a picture of what you have.

With a new tube in a tire, you have to make sure you can get the pump on the valve stem without pushing it (the stem) into the tire. Put the little knurled nut on the stem, or simply push against it from outside the tire.

You have to open the valve in order for the pump to work with it.

Take a look at the many websites and videos from this search. Hopefully it will make sense to you: http://search.yahoo.com/search;_ylt=...8&fr=yfp-t-600

You state that these are New tubes? I assume the old tubes were automotive/Schrader type valves?
http://bikeforums.net/attachment.php...hmentid=320168

IF the old tubes were using Schrader valves, BE Aware that the holes drilled into your wheel rims are oversized for presta/french valve stems. The oversize holes will cause a non- repairable puncture next to the presta valve stem. This can be prevented by installing a schrader to presta shim (a thin metal or plastic collared -not flat- washer inside the rims valve hole.
I have also had excellent results using 1/4 inch rubber grommets from Radio Shack or Hardware store.

Yes my pump is ive inflated presta valves before no problem 2 of my other bikes all have presta valves and the original tube was a presta the thing that's going on is the center piece the part you push down to let all the air out of the tube won't stay up as soon as I hook my pump up the center piece gets pushed all the way down and the tube goes back to zero and when I lock the pump on there the valve won't let air in ice even taken the tube all the way back out and tried to inflate like that I can get it to 30 or 40 psi before it dumbs

How about providing some photos of the pump, valve and pump nozzle?

Seriously? You got 30 - 40 psi into a tube without a tire around it? How big was it?

[QUOTE=Nermal;15687269]Seriously? You got 30 - 40 psi into a tube without a tire around it? How big was it
Exaggerating a bit it was only like 10-15 at the most. My pump is a black burn air tower 2 has 1 different settings for both type of valves I air my mtb and road bike with this all the time with no problems

It's either your pump-head or the valve. Work out which by trying your pump on someone else's presta valve, or borrowing another pump.

Or perhaps it's you - if you try both of the above and it still happens then I'd be suspicious.