2009 Chrysler 300 - Fuel pump trouble

Sometimes fuel pump runs car runs fine othert times fuel pump does not go on car does not start this is with a new fuel pump and fuel pump switch

Maka sure the relay is getting 12v in on the high side. Check continuity of the wires from the relay to the fuel pump to insure they are not damaged. Make sure the ECM is actually switching on that relay and the the wires to the relay are not damaged by checking continuity. Make sure the ECU harness is properly seated (reseat it) and while your at it make sure the pins look good.