Pumping Up a Schrader Valve

[brush3287]

Now this may seem lame, especially as I've been riding various machines over a 45 year period! I'm having trouble getting air into an MTB tyre using a pump & a schrader valve. Part way through inflating the thing air is coming out of the valve faster than I can pump it back in.
Can anyone tell me what's happening & what I can do about it?
Ta

 

[alfeng]

You should probably buy a new/different pump ...

NOT a mini-frame pump, BTW.

 

[genedan]

Yeah what you want is a good floor pump. There should be a lever on the head of the pump that locks onto the valve, no air should come out.

 

[dot]

Even with floor pump I was in trouble putting more than 5 bar into MTB slicks. Use the third hand-leg-anything to keep your pump valve in place.