This quest is located in the refinery, north of burbclave. The only way to reach the refinery is by flying, so get someone with pilot or get the fly mutation to get there.
On the lowest level of the refinery there are several rooms represented by %% on the map: Pumping Station, Desalinator Wedge, Catalytic Reformer Bay, Hydrocracker Bay, Merox Room, and Isomerization Plant. On the second floor in a room in the north there's a console that when ed at will display the current configuration of the refinery, along with the status of the rooms. If one of the above rooms says or is red on the console then it will need to be repaired before the quest can be finished. to fix the room, this may take several tries. Sometimes the rooms will require parts to fix. With the exception of the liquid reservoir assembly, all can be scavenged in the lower level. The liquid reservoir assembly can be found in a toolbox in the northwestern most square of the second level which is only accessible if the Isomerization Plant is broken. Once the rooms are fixed they will say The machinery hums softly.
When all rooms are repaired return to the console mentioned above., and set the plant to the same order as mentioned above. Once this is done . The refinery will start to produce gas.
Pressure will build up in the tanks, there is a console (nearly right above the one you configure) where you can vent the gas to prevent the pressure from overloading and exploding. If either pressure or gas capacity exceeds 100%, the refinery will basically explode and break down and you will have to start over from scratch.
Now you need to ship the gas. Go to the helipad on the uppermost level anduntil you find a bottle rocket. While still on the helipad to summon the tanker. Go to the eastern most room in the second level (where the configure console is), tanker fueling. When the tanker arrives to start the fueling process, finishing the quest.
This earns you about 650xp and 30,000 dollars for a 100% full tanker.
Significantly less for anything short of full and payment is based on how much gas was piped to the tanker.