unity very high character jump

I decided to make a little 2d game in unity before the new year, the question is that when I press jump (upArrow) it's like a rocket, it goes flying and I never see it again, but, why it happens this? This is the code:

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class player_controller: MonoBehaviour {

public float maxSpeed = 5f;
public float speed = 2f;
private Rigidbody2D rb2d;
private Animator anim;
public bool grounded;
public float jumPower = 6.5f;
private bool jump;

// Use this for initialization
void Start () {
    rb2d = GetComponent<Rigidbody2D>();
    anim = GetComponent<Animator>();

}

// Update is called once per frame
void Update () {
    anim.SetFloat("speed", Mathf.Abs(rb2d.velocity.x));
    anim.SetBool("grounded", grounded);

    if (Input.GetKeyDown(KeyCode.UpArrow))
    {
        jump = true;
    }

}

private void FixedUpdate(){
    float h = Input.GetAxis("Horizontal");

    rb2d.AddForce(Vector2.right * speed * h);

    /*  if (rb2d.velocity.x > maxSpeed)
      {
          rb2d.velocity = new Vector2(maxSpeed, rb2d.velocity.y);
      }
      if (rb2d.velocity.x < -maxSpeed)
      {
          rb2d.velocity = new Vector2(-maxSpeed, rb2d.velocity.y);
      }*/

    float limitedSpeed = Mathf.Clamp(rb2d.velocity.x, -maxSpeed, maxSpeed);
    rb2d.velocity = new Vector2(limitedSpeed, rb2d.velocity.y);

    if (h > 0.1f)
    {
        transform.localScale = new Vector3(1f, 1f, 1f);
    }

    if (h < -0.1f)
    {
        transform.localScale = new Vector3(-1f, 1f, 1f);
    }

    if (jump)
    {
        rb2d.AddForce(Vector2.up * jumPower, ForceMode2D.Impulse);
    }

    Debug.Log(rb2d.velocity.x);
}

}

everything works fine except for the jump, which instead of jumping is like taking off. Thank you very much for the help