LANDCRUISER 100 SUB TANK

Submitted: Monday, Dec 18, 2006 at 10:20
ThreadID: 40455 Views:12376 Replies:5 FollowUps:6
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Hello,

I have just bought a second hand 2003 Landcruiser 100 4.7L V8 Petrol and I have a question regarding the main / sub tank.

The question is - Is the correct operation of the main / sub tank as follows or do I have a problem.

If the main tank is selected (no sub indicator displayed) The sub tank is used first and then the main tank.

If the sub tank is selected (sub indicator displayed) The sub tank is used first and then the main tank.

I think that when I select the main tank - the main tank should be used and the sub tank should only be used if selected.

Regards

Carl
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Reply By: keepingitreal - Monday, Dec 18, 2006 at 10:51

Monday, Dec 18, 2006 at 10:51
Hey Carl, whichever tank is selected is the tank you will use . IE select sub. ,uses sub,then switch to main to use main and vice versa! Keep it real!, Regards Kirsten
AnswerID: 210945

Follow Up By: charbinson - Monday, Dec 18, 2006 at 11:09

Monday, Dec 18, 2006 at 11:09
Thanks for that, so I assume that when I select Main and petrol is used from Sub there is a problem

regards

Carl
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FollowupID: 470997

Reply By: Grumpy in WA - Monday, Dec 18, 2006 at 11:14

Monday, Dec 18, 2006 at 11:14
Hi Carl,
The slection of the tank you use is manual, you decide what to use. If you fail to switch over soon after the warning light comes on the you will eventually just run out of fuel. There is no automatic switching over mechanism.

Hope this helps.
AnswerID: 210952

Follow Up By: charbinson - Monday, Dec 18, 2006 at 11:17

Monday, Dec 18, 2006 at 11:17
There might be a fault as when select the main tank the sub tank is being used. And when the sub tank is below 1/4 tank the main tank is used.

This is confusing when trying to see how much fuel one has remaining

regards

Carl
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FollowupID: 470998

Follow Up By: Grumpy in WA - Monday, Dec 18, 2006 at 11:25

Monday, Dec 18, 2006 at 11:25
Hi Carl,

The best place to post a question like this is on the LCOOL mailing list.
Sign up at: www.lcool.org/index.html
There will be someone on these lists that has experienced something similar before.

There are also technical pages in this web site that may help.
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FollowupID: 471000

Reply By: Robnicko - Monday, Dec 18, 2006 at 12:46

Monday, Dec 18, 2006 at 12:46
Carl,
Sub light off = Fuel delivery from Main tank.
Sub light on = Fuel delivery from main tank but fuel transfer happening from sub tank into main tank. When main tank gets full the sub light goes off and fuel transfer from sub to main stops. Fuel may still remain in the sub tank. You should see the sub tank gauge drop and the main tank gauge go up!

Rob
AnswerID: 210963

Follow Up By: Grumpy in WA - Monday, Dec 18, 2006 at 14:24

Monday, Dec 18, 2006 at 14:24
Hi Rob,

Are you sure about that?

On my HZJ105 fuel is delivered from the main tank when the sub light is off. The sub tank stays full until I switch over to use that tank.
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FollowupID: 471021

Follow Up By: Member - Roachie (SA) - Monday, Dec 18, 2006 at 14:37

Monday, Dec 18, 2006 at 14:37
Rob,
that is the system Nissan uses on the GU, but I always thought Toyota used a system like the previous respondants had described.......
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FollowupID: 471022

Follow Up By: luch - Monday, Dec 18, 2006 at 17:09

Monday, Dec 18, 2006 at 17:09
I am 98% sure Rob is correct, that a transfer pump is used to move the fuel from the sub to the main tank on all PETROL MODELS only

Diesel models you can select which tank you run off
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FollowupID: 471055

Reply By: Member - Phil G (SA) - Monday, Dec 18, 2006 at 18:53

Monday, Dec 18, 2006 at 18:53
I don't know exactly what system is used by the V8 100series but what you describe doesn't sound normal.
But, if it is the common Toyota setup which has fuel pumps in both tanks, and also solenoids for both fuel supply and return, then my money is on a sticking fuel return solenoid. So no matter which tank you are using, the return is going back to the main tank. Just my guess!

Cheers
phil
AnswerID: 211044

Reply By: Member - Shane D (QLD) - Tuesday, Dec 19, 2006 at 18:15

Tuesday, Dec 19, 2006 at 18:15
Dunno with the V8's
diesels DEFINATLY use the tanks as selected IE:
subtank (light on) fuel goes to motor AND returns to sub tank,
vice versa for main(light off).
Fuel gauge will adjust to what ever is in relevant tank.
7# petrols that have 4.5l motor have the fuel cross-over (like gu) because they have a high pressure pump in the tank ,maybe petrol 100's same?
If you are having difficulty working out whats going with yours there maybe solenoid stuck shut/partially shut giving you readings
Shane
AnswerID: 211217

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