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nissan
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Discussion Starter · #1 ·
Well I've put this in the auto electrical section b/c that's my best guess of what might be the cause of the issue, bit I'm just guessing.

My subtank is allowing fuel to drain/siphon into the main without having activated the pump. Takes quite a while
ie. full tank, full sub I'll start to notice when main is down to between 1/2 - 1/4
If I fill the sub when the main is low, it doesn't seem to happen.... Or at least I haven't been able to catch it happening :-(

I'm sure it didn't do this when I first got the vehicle (July) and whileits not a major issue (really) since Im not actually losing fuel, it does piss me off thinking I have a full sub, then look down to see it's only 1/3 - 1/2 full <arrgh!!>

Any thoughts/ideas of where I could start hunting will be greatly appreciated!!

Cheers,
Crazy
 

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nissan
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2,003 Posts
What sort of truck... Wagon, Ute?
What model truck... GU GQ MQ?
Factory Tanks or after market?

If it is a GU with factory setup the sub tank transfer system runs as a self test which will transfer a bit of fuel each time. Shouldn't transfer 2/3rds of a tank tho unless you do a lot of stop start.

Possibly a dodgy Sub Tank Computer if there is a fault...
 

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nissan
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My GU seems to transfer fuel if the vehicle is left idling for any period of time so it might be this occuring.
 

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nissan
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Discussion Starter · #4 ·
1999 ST GU diesel wagon stock tanks - sorry, shoulda though to put all that in initially <doh>

Yeah, I know about the "start up pump" but that's less than 30sec on startup, shouldn't be enough. If I pump it intentionally, it takes 10min or more for a full sub tank, at a guess.

Wasn't aware of idling causing it to pump, any idea why that much affect it?
 

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nissan
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This sounds normal to me. I wouldn't worry or change anything.
Try driving for 6 hours without restarting and I'll bet the sub doesn't loose fuel.
 

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nissan
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Yeah, it's normal. Lot of stop/start, alot gets transfered over the time it takes to drain the main. long highway drives with little stop start, no noticeable drop in sub level, but there is a drop.
 

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nissan
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Discussion Starter · #7 ·
alright, I'll go back to ignoring it, thanks guys.
like i said, just didn't notice it initially - although I did do fraser almost straight after getting it, so there was lots of highway driving straight up <shrug>

thanks everyone!
 

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Nissan GUII 3L Patrol
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it confused my first 3 months of Patrol ownership as well....... so your not the first and probably not the last to wonder " where is my fuel going ? "
 

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NISSAN GU PATROL
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Im not sure about this but its just a theory.

The sub tank is probably mounted higher than the main tank so the fuel can syphon to the main tank.

If it were the other way around you will be constantly running out of fuel from you main tank.
 
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