Fuel transfer repair.

The time has come to get the fuel transfer problem which arose mid Old Telegraph track 2 years ago. A job left until we got home.

The transfer pump worked if I applied 12v to it direct. For some time the sub tank gauge has read zero regardless of how full it was.

I think the most likely issue is a failed fuel tank float/sender in the subtank, which in turn will not let the computerised sub tank arrangement work. Sub tank light remains lit all the time when ignition is on. (Yes I have tried disconnecting the battery several times).

Of course if the sub tank level sensor proves to be ok there could be an electrical/computer problem. If that is the case the best option seems like getting rid of that little piece of electrickery all together & getting a manual on off switch to operate the transfer pump.

As the sub tank is not registering anything it seems dropping the tank & checking the level sensor is probably the best first option (& hope that it fixes the fuel transfer issue).

Now the question: Mechanic or auto electrician? (Please don't suggest I do it myself - if I was physically able to I would, but I'm not).

I´d say a sparky is best fit for the job.

Yeah an auto sparky should be able to determine the cause on this I reckon.

Hi cuppa, long time no read mate. I am no help at all because I have no idea how the system works but I want to follow this thread because I have no idea how the system works! Feel free to post any system diagrams here and keep us updated while you work through it. I would appreciate the info. Cheers

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Originally Posted by taslucas

Hi cuppa, long time no read mate. I am no help at all because I have no idea how the system works but I want to follow this thread because I have no idea how the system works! Feel free to post any system diagrams here and keep us updated while you work through it. I would appreciate the info. Cheers

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The 'system' where fuel can only be supplied direct to the motor from the main tank, which is situated right at the rear of the vehicle, & is controlled by rudimentary computerisation is the stupidest part of the Patrol's design. Admittedly the two horizontal oil filters in a hard to reach spot are stupid, but the fuel transfer system is king of stupid.
Whoever decided that being able to pump from either tank at will was not a good idea, or that putting the weight of the tank which must be used behind the rear axle made sense was a moron with no idea of good off road design. Hate to say it but Nissan should have employed the Toyota designer for the fuel transfer system.

I tried to work with the supposed computer diagnosis when on the OTT. Can't recall exactly the procedure now, something like Turn on ignition, press brake pedal 3 times, stick your finger in your ear & say 3 'hail nary's ......& then count the number of times a light flashes & refer to manual for what that means. All well & good but I got no light flashes & I'm pretty sure that I followed the instructions to the letter several times.

When we left home I had a sense that carrying a jiggler hose with us would be a wise idea, tested it to ensure I could get most of the sub tank contents with it, into jerries. Just as well or we might still be at Canal Creek!

Do you have to drop the tank on the utes Cuppa to access the sub tank sender? In the wagons there is an inspection hole in the floor. Which makes things easier for us. and if the sub tank gauge is not registering anything, I'd dare say the sender is kaput, and stopping the transfer pump from working.

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Originally Posted by mudski

Do you have to drop the tank on the utes Cuppa to access the sub tank sender? In the wagons there is an inspection hole in the floor. Which makes things easier for us. and if the sub tank gauge is not registering anything, I'd dare say the sender is kaput, and stopping the transfer pump from working.

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Yep it's in the top & impossible to get to without dropping the tank. I hope what you are saying is correct - it'd be the easiest way to fix the issue. Do you (or anyone else ) know of a failed tank gauge causing the transfer pump to stop working? I think it's the most likely cause, especially as the sub tank gauge was fairly erratic for a while before it stopped registering altogether.

Haha, I am much the wiser now, cheers [emoji28]

.......from under the great down under.

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Originally Posted by Cuppa

Yep it's in the top & impossible to get to without dropping the tank. I hope what you are saying is correct - it'd be the easiest way to fix the issue. Do you (or anyone else ) know of a failed tank gauge causing the transfer pump to stop working? I think it's the most likely cause, especially as the sub tank gauge was fairly erratic for a while before it stopped registering altogether.

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I don't know of anyone personally but I do know thew sender unit is linked to the transfer pump for auto shut off when the tank is empty, so if the sender is not working this would be the first place I'd be looking at. The sender needs to be replaced anyway...

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Originally Posted by mudski

The sender needs to be replaced anyway...

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My thinking exactly.

Update - with a bit of useful info for anyone who suffers the same problem of the subtank gauge not working & the fuel transfer being disabled.

Had an auto sparky look at it last week.

I thought he was pretty switched on (pun intended).

Rather than dropping the tank to get the sender unit out, he went to his office to get a paperclip, then got under the car & disconnected the the wiring from the subtank at the connector. He told me that if he then placed the paperclip between the contacts on the 'car side' of the the connector & turned on the ignition that if all was ok forward from that point that we should see the sub tank needle go up to register full.

Sure enough with ignition on the sub tank needle slowly went up.

So this appears to confirm that the problem is that the sub tank sender unit has sh*t itself as I suspected. Tuck that little test away for future reference if you think it may be useful.

Prices for replacement sender units were a bit eye watering from around $450 to $500! No such thing as 'aftermarket' that I could find. Different for the deeper 85 litre sub tanks that the utes have. (Same for TD42 as for 3.0l models)

Attachment 87514

However I managed to score one on a 'deal' off an ebay seller in Qld for $303.00. Paid an extra $5 for express delivery on Monday arvo & it arrived here (Vic) Wednesday morning. I was impressed by that.

Will be fitted next Monday morning. Hopefully will resolve the transfer issue.

Yeah great info there mate. I will put that trick into the memory bank.

Woohoo! We have a fully functioning sub tank fuel gauge & fuel transfer system again.

Once the tank had been dropped & the sender unit removed the problem was pretty obvious.

The entire float arm had detached from the main unit.

New unit fitted & all is as it should be. Happy days.

Attachment 87522

Does bypassing the sender unit also work to get the pump running?

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Originally Posted by mudnut

Does bypassing the sender unit also work to get the pump running?

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A very good question. I'm not sure, but it would be good to know, Could have saved a fair bit of siphoning with the jiggler hose on the Old Telegraph Track!

I've read that if you can zip tie the float up at the top so it reads full & that this will allow the fuel transfer system to work. Obviously in my case that wouldn't have worked, & even if the the float hadn't of broken off, dropping a full 85 litre tank would have been a non starter.

BUT when the auto electrician disconnected the sender unit connector & put the paper clip between the two contacts on the car side I should have checked to see if doing that (The subtank registered full even though empty) enabled the transfer pump to work . (After disconnecting the crank battery to reset it). It would be a very handy little trick if it works. Couldn't do any harm to try.

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Originally Posted by mudnut

Does bypassing the sender unit also work to get the pump running?

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The senders work off resistance. Or different levels as the sender float goes up or down. If you could mimic this somehow I’m sure you could get the pump to work


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Originally Posted by mudski

The senders work off resistance. Or different levels as the sender float goes up or down. If you could mimic this somehow I’m sure you could get the pump to work


Sent from my iPhone using Tapatalk

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Need to be a little careful doing this. The transfer also needs to stop when the gauge indicates empty and that will never happen with a bypass or tied up float.

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Originally Posted by Brissieboy

Need to be a little careful doing this. The transfer also needs to stop when the gauge indicates empty and that will never happen with a bypass or tied up float.

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Correct. but if it were for emergency purposes to just get some fuel into the main tank, manually watching main tank levels would be a must.

@Winnie @AB both have fitted long range sub tanks to their GQs without the factory transfer setup. I think they both just have an in-line pump and time it manually. They borh set it up for the Meetup in the middle 10 years ago. They dont have a factory guage.

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Originally Posted by MudRunnerTD

@Winnie @AB both have fitted long range sub tanks to their GQs without the factory transfer setup. I think they both just have an in-line pump and time it manually. They borh set it up for the Meetup in the middle 10 years ago. They dont have a factory guage.

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I had my belly tank running out of a 5 port valve, so what went from the tank returned to the tank on fuel return circuit. I had difficulty getting every drop out of the tank, so converted it to a transfer pump to tank set up and whilst it still had its own matched VDO gauge and sender unit, I just operated it via watching the fuel level rise in the man gauge. Worked flawlessly, and with in line filters the transfer pump was protected from the sludge and dust that gets into the fuel. The additional gauge was handy from the perspective it gave me an indication of the level of discharge. The pump was a cheapie and a diaphragme type from memory and didnt mind running 'dry' but in essence it had a coating of slimy diesel so all good.

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Originally Posted by MudRunnerTD

@Winnie @AB both have fitted long range sub tanks to their GQs without the factory transfer setup. I think they both just have an in-line pump and time it manually. They borh set it up for the Meetup in the middle 10 years ago. They dont have a factory guage.

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Yep works quite well and I think it was 38 minutes to fill it up.

Yeah I used to go off time for the transfer but now just check the gauge. I have mine set up with a changeover relay to the senders in each tank, while the transfer pump is running the factory gauge will show me the level inside the sub tank.

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