[Sergei]

You should use something like this.

pawn Код:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
    if(newkeys & KEY_FIRE)
    {
        new vid = GetPlayerVehicleID(playerid);
        if(GetVehicleModel(vid) == 510)
        {
            SetVehicleVelocity(vid,0.0,0.0,0.0);
                SendClientMessage(playerid,0xFFFFFFFF,"Jumping is not allowed!");
    }
    return 1;
}