This has been explained so many times on the forum and, of course, on the GSX manual.
GSX estimates the number of passengers from the total weight of all the loading stations, divided by 220 lbs, which is the industry standard for how much an passenger + luggage weights.
When you say "My last flight I had 67 passengers", what exactly you mean with this ? The simulator doesn't have a standard variable for the number of passengers, which means you are surely referring to an airplane that has a custom method to set the number of passengers. WHEN you used this method ?
IF you did it *before* calling GSX, and the airplane has correctly set the number of payload stations to indicate the number of passengers, the GSX estimate shouldn't be that far off.
However, there are some cases where the GSX estimate will surely fail, and are:
- Airplanes with a "combo" cargo + pax configuration. Since the sim doesn't have a way to tell addons if a payload station is cargo or luggage, GSX cannot tell and will use all the payload stations to make its calculations, resulting in an higher total.-
- Airplanes that loads passengers progressively. GSX will estimate the pax number when you call boarding or deboarding but, if the airplane is taking some time to load passengers, the number calculated by GSX will likely be lower than the final one.
In order to fix these issues, we have TWO separate systems in place:
1) The ability for airplane developers to TELL GSX the exact number of passengers, even while they are loaded, which is already supported by the FS Labs A320/319, so the two will always be in agreement.
2) The ability for the user to stop GSX from estimating the passengers number, in the GSX Settings. By disabling that option, GSX will always ask you for the passenger number during boarding/deboarding.
About the refueling, you don't say which airplane you used. Please read the GSX manual, because the refueling works in an entirely different way, depending if the airplane is flagged as having a custom fuel system or not.