Take gas cover off car dies

I have a 2000 malibu with 72000 miles on it. The engine light stays on and if I take off the gas cap the car dies. If left on the car runs. I thought the cap was not put on wrong according to the owners manual so I took it off and thats how I found out that the car dies. Any ideas? Thanks

Thats normal.. Get the trouble codes ran to see why the engine light is on.

The car goes into the shop tuesday oe wednesday so will post then. Taking the gas cap off and the car killing doesn't sound normal. It wouln't be the pump that sits on the left side of the car that looks like it pumps air into the ejectors. The pump has a little filter on it so I beleive it is a emmissions pump of some kind.

that is not normal, you can drive around with the cap off, the check engine light will come on in a few blocks. Might have a clogged PCV valve.