I forgot to provide one other link. This one has lots of information on the OBD2 CAN messages and how to interpret them:
However, I just realized that the PID you are looking for is not on your list.
I would suggest getting hold of a diagnostic scan tool and see if the tool can show the fuel level.
If the tool can do it, then there might be an issue with your code to read the list of PIDs (such as needing Extended CAN).
Also, note the link above has a section on Non-Standard PIDs and exceptions to ETI membership. Suzuki is on that list, which might be related to this puzzle.
I was not able to review your code. A screen shot of a small snippet of code will not help. It is necessary to see the full code, especially the code where you make the request message,