Improved sub tank transfer rate.

[Potsy]

Sorry for the hijack cuppa, but I have a main and sub tank and find that the sub tank leaks into the main even when the switch is not on, not at a great rate but overnight I can see a change on the gauges. Is this by any chance a common issue with the setup.
Mines a 2000 TD42T and I dont get any faults or alarms but am interested to know if this may be due to a faulty pump or maybe a rogue ockie strap protector to!

[jack]

Perhaps some numpty decided that he only wanted a pin hole breather and deliberately put the "bung" in the breather.
They can get a fair bit of pressure differential so maybe the tank breather sucked in the bung till it jammed.
Maybe he was having condensate issues or whatever
It's a longshot but I have seen people do really stupid shit over the years... especially a really ugly bloke I often spot in the mirror

P.S. the factory pump should transfer at 1 & 1/2 LPM.
To work out if the pump etc is OK empty then fill the sub, note the Litres and do the following
Litres added times 1
Divide that by 2 and remember for later
Litres added divided by 10
Multiply by 5 and remember for later
If it is a Diesel set your watch forward 7 minutes unless you disconnect the battery
If it is Petrol leave watch as is but deduct 172 seconds if it is a 4.8
Turn ignition on then off 3 times quickly then once slowly (do not start engine)
Forget what you remembered and if the tank transfers 30 litres in 20 minutes give or take or 70 litres in 45 minutes give or take it is probably OK

Thanks ET, good to see there is at least one other intelligent person on the forum.

[mudski]

Sorry for the hijack cuppa, but I have a main and sub tank and find that the sub tank leaks into the main even when the switch is not on, not at a great rate but overnight I can see a change on the gauges. Is this by any chance a common issue with the setup.
Mines a 2000 TD42T and I dont get any faults or alarms but am interested to know if this may be due to a faulty pump or maybe a rogue ockie strap protector to!

I cant see how thats possible as the outlet for the sub tank transfer is high up in the filler neck. When the transrer pump is on you can see the fuel flow out from the main tanks spout. Unless im missinig something.

Sent from my SM-P600 using Tapatalk

[the evil twin]

What Mudski said... ^^^^
Your sub cannot physically leak or siphon into the main

The sub will, however, transfer fuel into the main as part of the self test every time you start the engine.
This means over time and depending how often you start the engine your sub will decrease in contents but is totally normal for a Patrol

[MudRunnerTD]

Sorry for the hijack cuppa, but I have a main and sub tank and find that the sub tank leaks into the main even when the switch is not on, not at a great rate but overnight I can see a change on the gauges. Is this by any chance a common issue with the setup.
Mines a 2000 TD42T and I dont get any faults or alarms but am interested to know if this may be due to a faulty pump or maybe a rogue ockie strap protector to!

If you have an empty main tank and you go to the bowser to fill up and you take the cap off is there a rush of air? I would check your breathers as mine has suffered from this and was caused suction from the main tank drawing the fuel out of the sub..... Surprising. It should not do this at all though.

[the evil twin]

Do you have a pommy or Scots hetitage ET? Numpty.

Anglo-German... with several documented mental disorders...
Be afraid, be very afraid

[Cuppa]

Thanks ET, good to see there is at least one other intelligent person on the forum.

Who’s the other one?

[threedogs]

so everyone has blocked breather tubes ,, well the majority anyway
I thought it was normal to have a sucking sound when you release the filler cap
especially if near empty

[MudRunnerTD]

so everyone has blocked breather tubes ,, well the majority anyway
I thought it was normal to have a sucking sound when you release the filler cap
especially if near empty

Not sure 3D, i have certainly suffered from this same issue. When i did the Madigan Line i had issues and watched my Sub empty as much as 1/4 of its gauge while driving. at the time i put it down to very rough track and sloshing about as i was crawling in L1. it turned out that when i fitted my Long Range tank i had fitted the one way valve in the breather the wrong way round creating extra vacuum. add to this the split fuel line that happened in the second half of the crossing and my Fuel issues did my head in and i just put both symptoms together but they were not.

[Winnie]

My Patrol does not suck in air when I release the filler cap, my work Hilux with single petrol tank does though.