turbos have high pressure pumps in the tank and the entire system up to the injectors is normally at above 40psi and can be as high as 70psi under boost, so a leak isnt too hard to locate
so assume that its a carb car where talking about since you said you have a regal , not a turbo car , your fuel line is not underpressure , the fuel line under the car on carb cars is a suction line from fuel pump to tank . ( no pump in the tank) and not under any pressure , the return line may see some pressure but again less than 7psi and the line from the feul pump at engine to carb sees about 7psi
its possible the fuel smell is just from an exhaust leak and a hole or bad seal in the cowl area and or the carb running pig rich due to cold choke or stuck choke , another possibility fuel line to carb is leaking (could be very slow drip since its only about 7lbs of pressure when running )and is drying up on a warm engine , may not leak at all when engine is off and pressure is down . another thing to check is these cars tend to rub the fuel line where it passes thru the frame on the passengerside , its possible you have a leak and while running its drawing fuel and not spurting all over the place but when idle or sitting it may leak down into the frame rail
either way go over every inch and make sure it not a leak then check the carb inlet and the choke for sticking or a stuck or sunk float, and look at the exhaust for leaks at the header connections