the best answer to this issue is having a scanner hooked up and reading the code. Just because you changed the pump doesnt mean its a pump issue you could have a totally different issue. But yeah try the gas cap suggestion, if that works great. If not have your vehicle scanned, and this way you will know exactly what the issue is. A check engine light can be a number of things it would be difficult to attempt to answer a check engine light issue without a scan...