Leaking Gas on left side of gas tank, can't tell if it's the line

Only two are fuel lines, the main feed to the engine and the return line from the engine to the tank. One other gas tank line will be the EVAP line for sending gas tank fumes from the charcoal canister to the engine's intake manifold.
I think the other lines would be your brake lines to the rear wheels.

YouTube has many videos on repairing rusted fuel lines. Most people use the lines made of plastic in their repairs-takes special fittings though. These plastic lines have become very common now. In fact my '92 LeSabre has mostly plastic lines.

if it only leaks when engine running must be coming from fuel pump or fuel lines get it checked ASAP as fuel is VERY FLAMMABLE dont take any chances

Have you looked under the hood? (I don't mean to sound like a wise guy.) There are two shiney metal pipes one on the front of the engine and one on the rear as you look at it from the front. They run from right to left on the engine. These are the fuel racks that feed the fuel injectors, (assuming that you have a 3 litre or larger v6 engine). These can concievably rust at the left, (passenger), end and blow gasoline out the passenger side. It is also possible that gas could be leaking anywhere on the engine and roll off the passenger side of the engine or if the fuel line on the driver's side has rusted over a cross member of the frame and possibly roll to the passenger side. Also, there is pretty good pressure on the fuel line when it is running. If there is a rust hole on the right side of the line itself, it could spray to the passenger side, hit something and drip off from there. These are just possibilities. Good luck. Jeff M.

You either have a gas leak or a thief. Check the gas lines that run under the car and the connections under the hood

Check fuel lines that run up side of engine. Lots of times they can chaffe against block and leak. Also be careful when filling car, if you top tank to top of fill neck that puts pressure on lines to canister where canister will fill w/fuel and literally ruin vapor canister.

It depends on where on the car it is leaking. For sure if it only leaks with the car on it is leaking from a gas line. There are rubber lines connecting the steel lines to the tankand they can go bad. The steel lines run up one side of the frame, usually the driver's side. They can also corrode and leak.
If you are quite sure the leak is on top of the tank then it has to come off. There are 2 straps holding it on and the bolts should be at the bumper end. Don't be surprised if they break off, they can be replaced.You will also have to unbolt the fill neck at the top because it will come down with the tank. Leave the cap on. You should block the tank up before you start and have a hydraulic jack so that once the straps are off you can slowly lower the tank with it. Make sure you have a piece of wood between the jack and the tank so you don't poke a hole in the tank. Gas as a liquid is not combustable but the vapors are so as long as you don't smoke or create a spark you should have nothing to worry about. That's why you use the wood blocks.
When you can see your problem you can get rubber gas lines by the foot and hose clamps at the autoparts store. If the steel lines are bad then steel brake line is an acceptable substitute and can be bought by length or by the foot. Hope this helps.

This sounds like you have a leak at the fuel pump and sender unit, either in the unit mount or in a fuel line. Check under your back seat for an access panel if you have one then remove it and look at the pump and sender mount to see what is leaking, you may have to start the engine to get it to leak as it may only leak under pressure, hope this helps, let me know

The Lines are simple if it's a 2.4 EFI the lines run on the driver side inner rail from the center top of fuel tank, and up the middle of the firewall to the injector rail or throttle body carburetor there is also one line that runs from the evap canister back to the tank and to the fuel system three lines total one is a return line the large line is the main fuel line and has the fuel filter mounted on it and is under the driver side door inside the frame rail.

You probably have a defective fuel-tank selector valve. Its located on the left frame rail, halfway down. While the vehicle is running, tank"A" is pumping fuel to the engine, while tank "B" is getting the unneeded fuel that is returning from the engine. Thats why it is overflowing.

It sounds like the return fuel line is leaking. There are two fuel line and one is the high pressure line which goes to the fuel pressure regulator then to the fuel rails. There is then a return line from the fuel rail to the gas tank.
With the amount of fuel leak, it's going to be the return line since it's not that bad compared to the high pressure side. Follow the fuel lines from the drivers side around the steering shaft to the engine. The high side and low side (return) run side by side and you should see it leaking when the engine is running.
Good luck and hope this helps.