when i put faucets or shower on pump runs for few seconds then goes off for few seconds

Ah, shower pumps! I am glad these things aren't as popular on this side of the pond. But from what I can see perusing our UK newsgroup interface (

), and intermittent operation like that could be caused but the pressure switch  fault or in need of adjustment or it could be an installation problem where the pump pushes more water than the supply can provide and has to wait until there's enough water to pump again. Could also be an airlock (trapped air) in the supply pipe.  There are a myriad things that can go wrong with these, from plumbing to electrical and everything in between.   I suggest you run a search for "shower pump" here: browse through results and then narrow it down by feeding the search more details like the manufacturer or a model of the pump, location of the pump etc.