I hope this is the right section to post my issue.

I have a 2000 Mitsubishi Montero Sport.

After I fill up my fuel tank the check engine light comes on. (not right away, usually after 3 startups). This has happened at least 4 times, the same way every time. And then when the tank reaches 1/4 or below the light will go off.

I have tried 2 different gas caps, and yes I make sure it clicks a number of times to make sure its closed, tried different gas stations.

I just not understanding what the issue would be if at 1/4 a tank the light goes back off and then when I refill it comes back on.