[RajatPawar]

You check "GetVehicleModel" wrong. It returns an integer value (the vehicle model or 0 if not existing), while you are checking it for boolean values! (true/false)
So, this:

pawn Код:

public FuelUpdate()
{
    for(new i = 1;i<MAX_VEHICLES;i++)
    {
        if(GetVehicleModel(i))
        {

should be:

pawn Код:

public FuelUpdate()
{
    for(new i = 1;i<MAX_VEHICLES;i++)
    {
        if(GetVehicleModel(i) != 0) // or if(GetVehicleModel(i) > 400 && GetVehicleModel(i) < 611)
        {