Hey Vijay, did you solve your problem?
I am having the same problem with the same water pump. I'm using a relay and for some reason the pump works only sometimes. The pump works fine when I connect it directly to the power source. When in the circuit only sometimes. I checked with a multimeter and when the pump is connected the current goes high and then it drops to zero like in a second. If I connect a normal motor instead the circuit works perfect.