07 Tahoe fuel door wont lock
 

Someone has been trying to steal gas from our vehicles off and on for the last month or so. More than once the 07 Tahoe has "chirped" at night and when I go out to see what caused the alarm to chirp I find the fuel door pried open. Normally you cannot open this fuel door unless the vehicle is unlocked so I assume someone is using a screw driver to pry it open. They have gotten gas out of my truck and van before which dont have alarms....

Last night the same thing happened again. The alarm on the Tahoe chirped and after grabbing my gun and running out there to see who was there I found the fuel door open (I let my german shepard run the property and couldn't find anyone to shoot so they got away again). The problem is that the fuel door will still shut but no longer locks when the vehicle is locked. My guess is that something has happened to it from being pried open. The fuel door will shut so the spring loaded gizmo (for lack of a better word) is still working... any ideas on how to get it to lock shut again?? I really would like to know when this gas thief comes back and the alarm wont go off if the fuel door isn't locked. any ideas on how to get it to lock again? Is there a reset I can do?

thanks