possible fuel leak

[noriceplz]

So as i said in yesterdays post, the questions were definitely coming. Again I stress that I am new to all this so i apologize if I ask the same thing 50 times before i understand. When i first purchased my Z i was informed of a minor fuel leak (loose clamp, problem solved?) I had a buddy of mine whose a mechanic, works on all his cars, does it for a living in the army blah blah come check it out. He proceeds to find the suspected leak and tighten the clamp and tells me i'm good to go. Few days later i'm driving her and notice a ridiculously strong gas smell. I park the car and start sniffing and its not coming from the engine bay but from the exhaust. Any ideas? thanks in advance for any replies.

[Rogue One]

Sometimes you may find that the exhaust smells like gas. This is normally a problem with the air and fuel mixture as your fuel injector may be sending too much gas through the engine and not all is burning. This can easily be fixed by having your engine properly tuned. You also may not be using the correct grade of gasoline. Therefore the engine and exhaust are not working properly which results in gas like odors emerging. You may also find that the fuel injector is clogged and needs cleaning.

[DCaff300ZX]

+1 to all of the above, with a failed injector seal also a possibility if there is a lot of fuel in the exhaust. Sometimes when the injector itself fails it will fail wide open, or also closed but it's possible yours may be failed open.
Your mechanic buddy hopefully can diagnose the injectors for operation?