Drained the tank today.

There is about 12 liters left in the tank. I didn't want to go all the way as I don't want the pump to run dry.

Make sure the filler cap is loose to allow air in.

There are two ways of doing it.

You can either provide power to the plug under the right rear seat. I didn't like this method as it seems to start pulling air after a few seconds and then you have to wait a while before pumping again.

I don't know why the VCDS didn't do this. Perhaps it activates the the other pump that sends fuel from one side of the other as the fuel tank is a saddle design over the propshaft.

12 volt source on the left, ground on the right. (You use these points to connect jumper cables as well, as the battery sits under the front left seat)

12 volt on the right. Ground on the left

Or you can use VCDS with the intank pump's power plug connected.

Select Engine
go to Basic settings
select group 035
clickthe ON/OFF/NEXT button. The pump will run for 30 seconds. Press the button 3 times again and the pump will run 30 sec again. Repeat.

In progress

The rate of flow it pumps out

Did not even think of using the pump to drain. I just pulled the filter assembly out on drivers side and stuck a fuel line in the tank a six gallon tank not the ground and siphoned out with a hand pump to start flow.

The driver side has the primary chamber of the fuel tank. It is larger than they secondary chamber on the passenger side. Still had about four inches of pump below fuel after draining 6 gallons from the tank.

 

Did not even think of using the pump to drain. I just pulled the filter assembly out on drivers side and stuck a fuel line in the tank a six gallon tank not the ground and siphoned out with a hand pump to start flow.

The driver side has the primary chamber of the fuel tank. It is larger than they secondary chamber on the passenger side. Still had about four inches of pump below fuel after draining 6 gallons from the tank.

I have attached a decent 3D drawing of the tank, unfortunately not alot on operation of the system.