Try out:
Go 21/6/3 (he already has high base-health, the +3 mana/5 helps him tremendously)
Replace 3 Blues with Scaling Mana Regeneration (you can afford to lose 7MR@18)
CAST ALL OF THE SPELLS, BWAHAHAHAHAHAHA. Seriously though, i tried out Lucian a few weeks ago (admittedly I'm awful at adc, but w/e) and thought he was pretty weak. This build actually looks pretty beast though - the Muramana proc-ing on both passive shots sounds very strong. NJ dude, might give Lucian another try now
This looks pretty standard except for the muramana. Whats the reasoning behind the 
?
In my experience Lucian doesn't need that much mana since even with max CDR you aren't able to spam your spells fast enough to deplete it fully in a team fight. Also, since muramana has an on hit modifier you're better off using it on a more autoattack heavy champion, since Lucian's passive only procs muramana once.
I generally find that once I get a 
my manna issues are fixed.
I'd replace 
with a 
or 
.
As a Lucian main, I tried really hard on the PBE and the first few weeks of his release to use a build that wasn't the standard marksman build. Although some of them are quite fun, they simply don't pack the damage that the standard Marksman build does (by this I mean Beserker's Greaves, Infinity Edge, Phantom Dancer, Last Whisper, Blade of the Ruined King, and Bloodthirster with the option of a defensive item/Trinity Force replacing one/two of those).
Yes, Lucian does great burst, but I personally don't like building around it. My usual builds has a Trinity Force in it as I just love the item on Lucian, but that's about as far as I go into the burst Lucian idea.
With that said, I have nothing against the build. It's a lot of fun (I've tried a similar build a number of times) but it isn't what most people expect from a marksman. I wouldn't be surprised that if you run this build in Solo/Duo queue you are going to get some flame, so I would tell your team so they can mold their choices/builds around it accordingly and not be surprised when they start checking out your build.
The main problem with this build is that it's too weak early for me. I prefer to build strait into triforce, also weak early but not as weak as having a tear.
