Character refuses to fly

Hey guys, i am trying to make the player fly, but i can’t make it work! I am using the Standard First Person Character, and i am trying to make him be able to fly when he enter the water so he will not be traped or something. The problem i am having is that he just doesn’t fly. If i add my script to a cube or anything else, when i press space i can make them fly, but not my character! I tried removing it’s scripts but still it doesn’t go. Someone know why? Can you help me?

This is my script, you can test it if you want:

using UnityEngine;
using System.Collections;

public class Fly : MonoBehaviour
{
    bool JumpPressed = false;
    public float jumpAccelleration = 3;


    void Update()
    {
        if (!JumpPressed)
            JumpPressed = Input.GetKey(KeyCode.Space);
    }
    void FixedUpdate()
    {
        if (JumpPressed) GetComponent<Rigidbody>().AddForce(new Vector3(0, jumpAccelleration, 0), ForceMode.Impulse);
        if (JumpPressed) JumpPressed = false;


    }
}

I’ll take a stab in the dark, but did you change the mass of your character? If the mass is too high, then the acceleration value probably would not have any effect. Since you say it works on cubes and you have removed all other scripts, I would compare the properties between a standard cube and your character.

One different solution would be to send the Jumppressed bool to the character controller script. Add your condition in their script. That should make their script take your conditions into account.