2000 GU 4.2ltr Patrol Diesel Sub Tank

Hi Navara09,

The sub tank fills the main until the it either empties the sub tank or the main tank is full. I'm guessing from your words is that you filled both tanks first, so the sub tank can't fill the main until you use some first.

Cheers Pete

You will also notice that when the main tank is down a bit each time you start the vehicle about 1 ltr is pumped over from the sub tank.

You can check and see if the pump is working by starting the vehicle (once the main tank is lower than 3/4 full) push the sub tank button then open the main tank filler cap and you will see the fuel being pumped into the filler about 75mm down the tube.

This is how my 2000 4.2td Patrol works.
As said above the sub tank pump will not work if the main tank is full.
If nothing works then reset as described above.
The easiest way is to disconect the battery negatives at the post.

navara
my 2004 patrol will turn on aux tank (switch will light up) for about 15 seconds even if both tanks are full, every time you start the car the sub tank will pump for a few seconds so always have fuel in sub tank or your pump will have a short life, also if you just change the fuse it will not reset the switch so you must disconnect the battery for a few mins this resets the switch often if the brake light fuse is blown I have to reset the sub tank switch if you search this forum you will find a lot about this sub tank switch as it catches every owner until they are told
good luck