I have an intermittent problem with starting the engine. It can reoccur weeks or even days till it happens again. When I turn the key to start the engine, nothing happens but I hear a hissing sound near the left side, underneath of the car. Is there some type of electrical connection that may feed a relay near the gas tank and closes the starting circuit? After 15 to 30 minutes, the car starts normally. An electrical schematic or suggestions would help me troubleshoot this problem.