Fuel Source cannot be resolved until you get to Nar Shaddaa, so don't worry about that. (There is more to the Fuel Source quest that didn't make it into the final game. You can re-instate the intended behaviour to get a reward from Grenn (and possibly G0-T0) by downloading a fix (for the PC version) from the
TSL Restoration Project).
Smuggling never causes me any problems.
On the LS path the steps are:
Talk to Grenn after recovering your equipment and learn about the bounties and fuel source quests. During this conversation Grenn will talk about smuggling on the Citadel station.
Later, when you help the Ithorians to escort their droid, you should come into the possession of a modified hold-out blaster. Take this to Samhan Dobo (you can take it to Grenn, but this isn't required) in his shop and ask him about it. Press the issue until he admits his involvement in the smuggling operation. Say you want in and get details of the three items he wants you to steal.
At this point you should be able to go back to Grenn and tell him what Samhan wants. Grenn will give you the three items (don't steal the items; that way DS points lie, and you may lock yourself into the DS resolution of this quest) and you can return to Samhan. Accompany Samhan to docking bay 3 and Grenn will show up to make the arrest.
The DS path is much simpler: Don't talk to Grenn about smuggling and steal the items for Samhan. When you have all three, you will accompany Samhan to docking bay 3. When the TSF turns up, kill them (Grenn will not be with them on this path).
It is possible that you have left the resolution of the quest too late. There are some nasty dependancies between some of the Citiadel quests; if this is the case, the quest may have become insoluble.
