Character controller jumping is unresponsive

I made this script and it's supposed to use the T butting to jump but it will only jump about 1/3 of the time

 using UnityEngine;
 using System.Collections;
  
 public class PlayerMovement : MonoBehaviour {
     public float curSpeed;
     public float acceleration = 5;
     public float decceleration = .2f;
     public float jump = 20;
     public float gravity = 21;
     public float airAcceleration = 2.5f;
     public float jumpAllowTime = .1f;
  
     float jumpAllowTrack;
     float moveSmooth;
     CharacterController cont;
     bool run = false;
     Vector3 curMove;
    
     float walkMoveV;
     float runMoveV;
     float stopMoveV;
     float airAccelerationV;
     private Stats Player;
    
     void Awake (){
         Player = GetComponent<Stats>();
     }
     // Use this for initialization
     void Start () {
         cont = GetComponent<CharacterController>();
     }
    
     // Update is called once per frame
     void Update () {
        
         if(Input.GetKey (KeyCode.A) || Input.GetKey (KeyCode.D))
             run = true;
          else
             run = false;
        
        
         curMove = new Vector3(curSpeed, curMove.y, 0);
        
         //sprint and movement.  
         if(run == true && Input.GetKey (KeyCode.LeftShift))
             curSpeed = Mathf.SmoothDamp(curSpeed, Input.GetAxisRaw ("Horizontal") * Player.runSpeed, ref walkMoveV, moveSmooth);
        
         else if (run == true)
             curSpeed = Mathf.SmoothDamp (curSpeed, Input.GetAxisRaw ("Horizontal") * Player.speed, ref runMoveV , moveSmooth);
        
         else
             curSpeed = Mathf.SmoothDamp (curSpeed, 0, ref stopMoveV , moveSmooth);
        
        
         if(Input.GetKeyDown (KeyCode.T) && jumpAllowTrack >= 0)
             curMove.y = jump;
        
         if(cont.isGrounded){
                 curMove.y=0;
                 moveSmooth = acceleration;  
                 jumpAllowTrack = jumpAllowTime;  
         }
        
         if(!cont.isGrounded){
             curMove -= new Vector3(0, gravity * Time.deltaTime, 0);
             moveSmooth = airAcceleration;
             jumpAllowTrack -= Time.deltaTime;
  
             }
  
         cont.Move(curMove*Time.deltaTime);    
        
     }
 }

How can I fix this?