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Is there anyone out there that can help me with the setup of the sub-tank within the GU.
My plan is to:
1 - Piss off the Nissan control module which keeps on getting confused
2 - Re-plumb the sub tank to directly feed the motor, rather than transfer into the main tank
So I am starting an information search:
1 - Is there someone out there already producing such a conversion?
2 - Where is the sub-tank module located?
3 - Does anyone have a wiring diragram for the module, pump and lights?
I'm tipping similar problems to me. Sometimes the sub tank just wont turn on meaning you either have to fuel up again earlier than planned or sit on your ass until it decides to work. I have an electric fuel pump just after the main fuel filter and I was just going to plumb the sub tank as you said and just use the factory pickup. Then the fuel gauge would still work and I'd just be drawing from both tanks at the same time. Now I'm just going to piss it off all together and run a custom tank Well it is a comp truck
Be carefull if your GU is a petrol.
the fuel pump in the sub tank is a lower pressure transfer pump, not the higher pressue delivery pump that is found in the main tank.
i found this out when i bought a long range replacement sub tank from brown davis.
when petrol GUs are converted to gas you are left with the sub tank.they change the fuel lines so the sub tank feeds the engine direct.
but on a long hill at full throttle the transfer pump cannot deliver fuel at the same required pressure that the original delivery pump can.i ended up sorcing the right pump and changing it. the preformance of my 4.5 was noticable immediatly.
Cheers Grant.
GU III TD42T UFI18G Cross Country IC, 20 PSI. Neeeeeed mooooore Fueeeeeel.
GUEEY wrote:Be carefull if your GU is a petrol.
the fuel pump in the sub tank is a lower pressure transfer pump, not the higher pressue delivery pump that is found in the main tank.
i found this out when i bought a long range replacement sub tank from brown davis.
when petrol GUs are converted to gas you are left with the sub tank.they change the fuel lines so the sub tank feeds the engine direct.
but on a long hill at full throttle the transfer pump cannot deliver fuel at the same required pressure that the original delivery pump can.i ended up sorcing the right pump and changing it. the preformance of my 4.5 was noticable immediatly.
Cheers Grant.
Nah I've got a ute. The leccy pump is more than adequate at lifting fuel out of the tank. The other option that I've seen and works well is to turn the main tank around 180degrees and place it in front of the diff almost where the sub tank sits.
Dirty wrote: Piss off the Nissan control module which keeps on getting confused...
Can't help with the info, but was wondering what problems you have had to want to do this.
John.
John,
About every 6-8 weeks the "sub-tank" light comes on and I have to do the whole battery disconnect process to reset it. Will then work fine for several tanks of fuel before I am back resetting all the clocks and radio stations again.
It is a '99 4.2TD Ute, The plan was to stick an internal pump into the sub-tank and build (buy) a replacement module which converted the switch to be just that, and the "sub-tank" light to represent "low fuel".
Shouldn't be too complex, just the job would be easier if the details where given to me, rather than having to reverse-engineer the whole thing.
i know i've said this thousand of times, make sure you have a good earth to the chassie, my 99 gu did not have one and was earthing through the handbrake cable, i put a earth strap from motor to chassie and the sub tank light has never come on again.
Not directly related but the current 4.8 petrol version no longer has a sub-tank. Not sure why it has been deleted, I will probably put in a 70 odd litre after market one with transfer setup when my new car arrives in 2 weeks.
jav wrote:i know i've said this thousand of times, make sure you have a good earth to the chassie, my 99 gu did not have one and was earthing through the handbrake cable, i put a earth strap from motor to chassie and the sub tank light has never come on again.
agree..
this was discussed heaps a while ago on exploroz
Again, the Gregory's for the ZD30 edition of the GU has great wiring and breakdown of most things... AGAIN, pity it's for the 3.0L! It should have the wiring for fuel tanks and info you require, but I agree with the earth check. For the sake of only a couple of bucks to start with, try putting on DECENT earth straps to the engine and tank electrics too. Run it and see, might work?
2000 GU II, 6.5L Chev Diesel (ex ZD30), lift, bar+winch, rear bar, drawers, fuel tanks I need a personal loan to fill... most of the regular touring gear.
jav wrote:i know i've said this thousand of times, make sure you have a good earth to the chassie, my 99 gu did not have one and was earthing through the handbrake cable, i put a earth strap from motor to chassie and the sub tank light has never come on again.
Jav, thank you for that, I will check the earth strap (or for an earth strap) which should at least stop me having to disconnect the because of the sub-tank controller.
manno74 wrote:Again, the Gregory's for the ZD30 edition of the GU has great wiring and breakdown of most things... AGAIN, pity it's for the 3.0L! It should have the wiring for fuel tanks and info you require, but I agree with the earth check. For the sake of only a couple of bucks to start with, try putting on DECENT earth straps to the engine and tank electrics too. Run it and see, might work?
Manno, I might take a walk tomorrow and have a look at the various workshop guides. My father also has a ZD30 wagon which is his grey nomad touring truck and was keen to convert from the transfer setup to direct motor supply for the sub-tank. So I might still take the project on.
Does anyone have access to Nissan information regarding the schematic, module wiring or any specifications that they would be willing to share?
Hi, My subtank pump shat itself too, nissan wanted about 600 big ones for a newy, told em to shove it and bought a $100 german one from supercheap.
I used the existing wiring to connect it up and it works fine, a bit slower than original. I mounted it in the same place as the other and made a simple bracket for it. too easy
It has been in the vehicle now for 4 years.
At that price i reckon I can replace it five times and still be on top!
cheers
Hutch
Here is a test to find whether your mission on earth is finished: If you’re alive it isn’t.
- Richard Bach
Well it is a comp truck 
