Fuel system

[JMR]

Hi all,
I’m from Zimbabwe, I drive a Nissan patrol 2007 TD42 pick up. I’m having a problem with my sub tank not pumping into my main tank any advise would be greatly appreciated.
It pumped for about 15min then the sub tank light came on and the fuel gauge dropped to empty.
The pump is working, I wired it direct to the battery and it pumped fine. Is there a sensor that may be gone or is it the fuel float/sender unit that’s gone?
I was driving on a very corrugated road when this happened!
Many thanks in advance for any advise you can give me regards to this.
Cheers for now

[the evil twin]

It will be the faulty Sender Unit causing the issue.
The Sub Tank Computer monitors the Sub Tank Sender, Main Tank Sender, Pump, Wiring and Switch
If that Fault Lamp is illuminated the Pump is electrically isolated by the Computer

First, disconnect the Battery for 10 minutes to reset the Sub Tank Computer.
If the Sub Tank Fault Lamp stays out (it will go out for a short period and do a self test) then that is great.
If the Lamp comes back on after the self test then you will need to replace the faulty component.

[Cremulator]

I just had this issue with the sub tank light staying on three days ago. I disconnected the main battery for 10 minutes and the sub tank light stayed off when I started the car the next time.
Thanks for the tip Evil Twin.

As a side question, does the sub tank ever engage automatically, like when the fuel warning light has been on for the main tank for any period? Or is it just triggered manually with the push button switch on the dash?

I filled my sub tank in November 2018 and it has been dropping slowly. The needle is sitting at half full now after 10 months.
I run my main tank to empty before refueling each time and I've filled the main tank exactly 10 times since filling the sub tank.

[Hodge]

I just had this issue with the sub tank light staying on three days ago. I disconnected the main battery for 10 minutes and the sub tank light stayed off when I started the car the next time.
Thanks for the tip Evil Twin.

As a side question, does the sub tank ever engage automatically, like when the fuel warning light has been on for the main tank for any period? Or is it just triggered manually with the push button switch on the dash?

I filled my sub tank in November 2018 and it has been dropping slowly. The needle is sitting at half full now after 10 months.
I run my main tank to empty before refueling each time and I've filled the main tank exactly 10 times since filling the sub tank.My understanding is there is a bit of fuel pumped from sub every time vehicle is started and is automatically transfered when fuel light comes on.

Just out of interest , why are you not using the sub fuel that much ? Don't drive enough or always only fill the main ?

[the evil twin]

Wot Hodge said ^^^^

Every time you start the vehicle the sub tank does a self test of the pump IF there is fuel in the sub AND the main is below 3/4's full.
Each time it does the test it will pump up to 1/4 litre of fuel which soon adds up.

[Cremulator]

That's good to know that the sub tank pumps a little each time you start the car under certain circumstances.
Hodge I filled the sub tank when we went camping last year and haven't been using the sub tank because I don't drive much or long distances, but mainly because I've been logging my full ups to monitor fuel consumption and want to keep consistency of milage from the main tank.
Since removing the full length roof rack the fuel consumption went from 14.66l/100km on the previous tank (with an average of 15.067l/100km over 10 tanks) to 13.68l/100km.

[Cremulator]

I might have spoken too soon on the sub tank light fix. After a short drive today it's come back on.

[Cremulator]

Not having much time to investigate this since September I drove around with the sub tank warning light on and the sub tank half full and not operational.
I had been reading about locating and testing the sub tank control module behind the climate control dials, but hadn't got around to testing it.

However in the meantime I read a reply in a thread on Patrol 4x4 by Frosty1970 that said "Before anyone does anything, Firstly, run a new earth from the body to the chassis. This will solve 75% of subtank problems!!"
In another post by Chaz he included this detailed image of where to run the earth strap.
http://www.nissanpatrol.com.au/forums/images/imported/2019/12/163.jpg
Last week I got around to running a cable the same as in the picture above.
http://www.nissanpatrol.com.au/forums/images/imported/2019/12/164.jpg
I disconnected the battery to reset the sub tank and after almost half a dozen individual small trips the sub tank light hasn't come on again!
It all seems to be working again as it should.

As a side note, from just initial tests, the remote to unlock the doors has gone from working no more than 2 metres away (and sometimes not for a few presses right next to the vehicle) to working pretty reliably from about 14 metres away.

I have to admit this is a fantastic double result from this very simple mod.

[rusty_nail]

Not having much time to investigate this since September I drove around with the sub tank warning light on and the sub tank half full and not operational.
I had been reading about locating and testing the sub tank control module behind the climate control dials, but hadn't got around to testing it.

However in the meantime I read a reply in a thread on Patrol 4x4 by Frosty1970 that said "Before anyone does anything, Firstly, run a new earth from the body to the chassis. This will solve 75% of subtank problems!!"
In another post by Chaz he included this detailed image of where to run the earth strap.
http://www.nissanpatrol.com.au/forums/images/imported/2019/12/163.jpg
Last week I got around to running a cable the same as in the picture above.
http://www.nissanpatrol.com.au/forums/images/imported/2019/12/164.jpg
I disconnected the battery to reset the sub tank and after almost half a dozen individual small trips the sub tank light hasn't come on again!
It all seems to be working again as it should.

As a side note, from just initial tests, the remote to unlock the doors has gone from working no more than 2 metres away (and sometimes not for a few presses right next to the vehicle) to working pretty reliably from about 14 metres away.

I have to admit this is a fantastic double result from this very simple mod.I do recall a member named rocket something or another having similar success an posting about it mate. Great result!!

Sent from my SM-G930F using Tapatalk

[Cremulator]

I do recall a member named rocket something or another having similar success an posting about it mate. Great result!!

Sent from my SM-G930F using TapatalkYeh I read a few threads and was hoping that this simple fix would resolve my sub tank issues. The remote working better is a real bonus.

[Cremulator]

Ok, so this sub tank earthing was working for about 6 short trips around town but 1.5 hours into a drive down the coast after Christmas and the sub tank light came on again.
I reset I again twice removing the earth lead from the main battery and it came on again within 15 mins of driving each time.
I added an additional earth lead from the main battery to the chassis and set off on another drive to the coast and it came on again after about 30 mins.
Seems like it wasn't the simple fix I was hoping for.

Should I now start to check error codes on the sub tank control module to try to determine what the problem is?

Also, on that same drive I later turned the parker lights on (due to rain around 3pm) and after driving with parkers on for about 40 mins they stopped working. No parkers, headlights or taillights (brake lights and indicators still functioned). I later diagnosed it had blown the 10a tail lamp fuse in the cabin. Might be unrelated but this is the first fuse its blown in 18 months since I've owned it.http://www.nissanpatrol.com.au/forums/images/imported/2020/01/143.jpg

[the evil twin]

To reset the subbie poota fault you can pull the sub tank fuse instead of taking off the battery earth... which is easier depends on what accessories and battery terminals you have.
My Cab Chassis had aftermarket cruise and they picked up the cruise control button power from the horn, every time you reconnected the battery the horn wold give a quick barp, total PIA

[Cremulator]

So I diagnosed the fuse blowing issue, which was caused by a new bike rack I had fitted which was plugged into the trailer plug.
Unrelated to the sub tank.

To reset the subbie poota fault you can pull the sub tank fuse instead of taking off the battery earth... which is easier depends on what accessories and battery terminals you have.
My Cab Chassis had aftermarket cruise and they picked up the cruise control button power from the horn, every time you reconnected the battery the horn wold give a quick barp, total PIAI haven't had much luck with trying to reset the sub tank controller by pulling the fuse. Are you referring to the 15A fuse in the bottom left (lid photo above) of the fuse panel?
I've tried removing it with the car off, leaving out for 20 mins, refitting and starting car.
No good.
Removing with the car running.
No good.
Removing when the car is off, then refitting it when the car is running.
Still no good.
So far only removing the earth wire from the battery when the car is off, turning on the headlights to flush any residual charge, then refitting the earth lead and starting the car clears the sub tank error light.

Next I'll be looking into how to check the error codes.

[the evil twin]

Fuse 24 - 7.5 amp

Amongst other things it is the Battery supply to the Sub Tank Poota.

Pulling it should reset the Poota and next time you turn the ignition on the Poota will do a self test.
If there is fuel in the sub and the main is not full after a minute or so if there is no fault then no warning light and all is good... if there is still a fault the warning light will illuminate and the pump will stop.

Checking the codes is a good idea... helps pinpoint the area that the Poota thinks is faulty.

I ran after market pumps etc in my last two patrols so working on memory for factory setups... aplos if anything I have said is wrong

[Cremulator]

Ah ok, I've been pulling fuse #27 labelled sub tank, I'll try that fuse #24 you mentioned.
Cheers.

[Cremulator]

Pulling fuse #24 worked to reset the sub tank warning light. It also resets the odometer, which I was hoping to avoid, but it's certainly easier than removing the negative battery cable.
Cheers for the tip!

[BIGY61]

Hahaha my patrol does the same thing and scares the 💩 out of me everytime without a doubt 😂😂