unity3d turn on off particle system

Question

i am trying to turn on and off a particle system i created.
I attached it to a prefab.

The code I am using is as follows

public ParticleSystem waterGun;

void Update () {
    if(Input.GetKey(KeyCode.W)){
        waterGun.enableEmission = true;
    }else if(Input.GetKeyUp(KeyCode.W)){
        waterGun.enableEmission = false;
    }
}

I want the particle system to play in front of the fps when a key is held down and stop playing when it is pressed.

Answer 1

Try using:

waterGun.Play();

and

waterGun.Stop();

And also, your logic is inverted, like Joetjah said.

Answer 2

You say that the "waterGun prefab is given to it" but you should be assigning an instance of a particle system in the scene to waterGun, not the prefab. A prefab doesn't exist in the scene.