Hello. When I turn the key in the ignition in the first position there is a quite loud noise from rear right side of the car. When I turn the engine on, the check engine light comes up and noise continues for a little bit longer and than its gone, but the check engine light stays on (I guess the noise is the fuel pump, am I wrong?). Car runs normally but I noticed strange sound of an engine starting around 3500rpm in any gear from the right side of an engine. Never noticed that sound before, sounds like the right 4 cylinders are lounder then they used to be before the check light came on. I am wondering what might be causing these two problems? Do you know what it could be? Can it be that the fuel pump is on its way and it is causing both of the problems? Any suggestions?

Thanks for any helpful info on this matter in advance :)