My bike has sat for a couple months on a dead battery. I jumped it a couple times but when I turned the key the dash would light up like normal but the fuel pump primed after 5-7 seconds which normally happens immediately. The bike would then start but not stay running. I put a new battery in it and the fuel pump was still delayed at first but seems to be priming normally now. After I put the battery in the check engine light turned on and it smells like it’s running rich. Gas in the tank is from a couple months ago but I’m not sure if that is relevant. My brothers bike has been sitting the same amount of time with the same gas and starts/ runs like a champ. Any ideas on why it would be running rich now or why it is throwing a check engine light? It ran flawlessly before it sat for a month or two.