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HZJ75 sub-tank troubleshoot

Reverend

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Nov 18, 2021
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australia
G'day All,

Recently bought a 97 HZJ75. Having some trouble getting the sub-tank to work. Manual says it should pump into the main tank rather than directly into the engine. So far I've checked all the lines and solenoids to be working. After some advice in further troubleshooting.

Cheers.
 

Swordfish

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Aug 14, 2020
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My FZJ75 rear tank pumps into the main tank. It takes about 30-40 minutes
My issue is the gauge on the sub tank on the dash isn't working....
 

CTS2

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Jul 8, 2017
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I have two HZJ75's, and have worked on many others. None of them pump from the sub tank to the main tank. They have two solenoid operated valves, to swap fuel supply and fuel return, between main and sub tanks. These are Australian models. I have no idea where you are from, overseas models may be different. Show us a photo of what it says in the manual. Pumping from sub to main tank is a petrol Landcruiser thing, and a Nissan thing, in my experience.
 

Bungarra

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Nov 4, 2012
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The 75 series (the great machines that they still are) did have a problem after time with the rear gauge not reading... A problem no doubt with the sender from the rear tank caused by corrugations and dust. I have a HZJ79 where the rear gauge shows 1/4 when full. I have been in other HZ's where the gauge does not show at all. This does not mean the rear tank is not going to work. You most likely have, but get up to speed on the Hwy, change it over and see what happens if you have not already.
 

CTS2

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Jul 8, 2017
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They also had a problem with the wiring to the rear tank gauge being ripped off by a stick or bush, because it is poorly routed across the gap between cross members. Better to modify it by adding in a piece of cable to enable routing around to the chassis rail and then back to the next cross member and into the main loom.
 

Reverend

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Nov 18, 2021
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So it is the Aussie model and the tanks pump the the two solenoids where by it goes onto the engine and the left overs feeds back to the tanks. I've checked all the lines and tested the solenoids to no avail and even wired up an aux switch to power the solenoids with no result. I'm doubtful about the sender being the issue as it's giving accurate reads on the amount of fuel at any given time. I've emptied the tank and pumped the lines manually to be sure there wasn't a blockage.

I can't see it on any specifications but want to check there isn't a pump of any fashion in the sub that may be the culprit?
What should the plugs be reading when the subtank light is switched to 'on' on the dash?? Should it simply be 12v? or should I be measuring in the ohms...
Any direction of further trouble shooting is awesome, thanks everybody.
 
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