I recently ran out of gas without any notice. Not a shimmy a shake. It simply Shut off. I put four gallons of gas in it and it still won't start. Could this be a clogged filter or a pump that went out? Could they all of a sudden just go out? It wants to turn over but won't. I listened to the tank to hear a pump kick on but did not hear it. Any advice? How much would it cost for a new pump to be put in? Thanks