'02 Z71 fuel tank capacity

[Ladys02z71]

Hi All, recently purchased an '02 Z71. My owners manual says I should have a 30gal fuel tank capacity. So, after running the thing well into "E", I have not been able to get more than 22gals into it.
Does it have a low fuel light or message? And do these things have a 7-8 reserve?
Thanks in advance.

 

[zora]

Do you have a check engine light on?
This happens at different gas stations?
Running well into empty is an excellent way to burn out a fuel pump.

 

[G-424287]

No, no check engine light, no messages...same at all stations, 20-22 gals.

 

[zora]

Have you looked at the tank to see if it collapsed?
Only other thing I can think of is a vent valve problem but I would expect an evap code to be thrown.