GU sub tank dash light

Matt,

Assumeing there is fuel in the sub tank, the other thing it could be is the sender unit in the tank is either stuck on the bottom of the tank or the plug from the sender unit has come off. Not sure about the GU, but the GQ had inspection plates above the sender units. They were under the carpet directly above the tank.

The pump will not work because it thinks the tank is empty because the warning light is on. Fix the sender unit and the pump should work.

Check for fuses, but I don't think this is the problem.

If you can find the inspection plates, remove them and have a look at the top of the sender unit. Make sure the plug is still attached. If that is OK remove the sender unit. there should be small screws holding it down. Remove screws and slowly remove sender unit. A small metal box with wirers going to it should be at the top and a wire lever coming from thr box. On the end of the wire a float should be found. Make sure there is no holes in the float and the lever moves freely up and down.

With the ignition lights on, and the sender unit still wired up move the float wire through it's arc until the float wire is as high as possible, then check the fuel gauge again , it should have moved. If it has, that means the float lever was stuck in the tank some how, this you will have to check and fix.

Sorry I could not help further but I have not worked on a GU fuel tank.

Wayne

Could domeone actually tell me how the setup works. The only time my subtank light comes on on the dashboard is when i turn the car on and all the lights come on. After that it doesn't matter if I have the tank full, empty or draining, no light ever comes on the dashboard, only the green light on the sub tank button when it's on.
Also, my low fuel warning light does not come on so I have to keep an eye on the fuel. It's always been this way too.
Thanks, Mark.

Had the same thing with mine couple of months ago....3lt 2001...was the sub tank control box gismo ...not in the tank but behind the dash below the radio......was lucky ...warranty job.

Hi Matt

Earlier GUs had a problem with the earth on the transfer pump not earthing properly. Check this too.

MikeF

Hi Matt
I have had the problem on both the 2000 3lt and the 2002 4.2 Nissan. The 3lt was easy to fiux, the computer had got confused and refused to transfer the fuel and the warning light was on.
Simple fix: remove earth lead from battery. If you have a dual battery system remove aux first, then under starting battery. After 20 seconds you will hear a click and then you can connect the earths back up.
If that does not work then it is a replacement of the pump. On my GU 4.2TD the replacement parts are different to what was in the vehicle. Worth chasing Nissan to do it under warrantee.
I am taking out the extended warrantee as one claim pays for it.
Ray

I just want to clarify what I was talking about to double check if I too have a problem (hope this doesn't constitute a thread hijacking).
My sub tank actually works, I press the button in and it starts delivering fuel to the main tank. When doing this, the green light within the button is on so it's all good.
What I was wondering was should the dash light also be on at this stage or does that only come on when there is a fault? Incidentally the pump does stop when the tank is empty.
The other problem which I don't think is related is the low fuel warning light. It's never worked.
Thanks, Mark.

Clean the blades on the fuse , that fixed the prob for me . Cheers Matt

Hi Matt,
I have a 2000 gu which does the same thing...mine is conflicting with my turbo timer!! what I have to do is remove my neg lead for 24 hours and the computer reset itself then it all works fine until I use my timer again...what a bloody p.......off.enough about my drama..I have read all the forum folks ideas and they all sound theisable to me try this and clean the conections. this might just do the trick.
All The Best In Health And Wealth
Jeffrey (AKA JD)

My 2001 4.2TD GU was doing the same thing.

All it requires is to remove the earth lead as that resets it somehow. Then using a length of wire and two round electrical crimps, make up an earth lead that connects the body to the chassis. Nissan did mine at a ridiculous cost (about $65) because they couldnt tell me exactly what they were doing. I wasn't happy when I saw what they had done, as there was less than $1 worth of parts.

Once that is done, you never have the problem again.

Regarding the pump.. another friend had the pump on their 4.5 petrol die whilst in Perth. Cost approx $700 for the pump. ME??? I'd have paid a bit more, changed the pump system and bought a replacement tank for the tiny 30L. I'm sure that you could install a larger tank that independently feeds the engine rather than the current situation where fuel is transferred to the main tank.

Fix the subtank problem permanently with the earth lead.

Good luck

Wayne

Thanks to all who shared their advise, I'll give the easy options a crack first and see how it goes, and by the way, the fault did happen at a bad time, following a siesmic track off the road from Paynes Find to Yalgoo... cheers, mat