Connector tubes (injector connector tubes) carry high-pressure fuel from the rail or head passage to the injector and seal the connection; worn or leaking tubes cause fuel knock, hard starts, and leaks on engines like the Ford Powerstroke and Navistar DT466. We stock OEM-brand connector tubes and related sealing hardware, many with no core charge and fast US shipping. Verify the tube against your engine and injector by OEM part number before ordering.