100 Cruiser Sub Fuel tank X feeding into main

Submitted: Thursday, May 13, 2010 at 16:47
ThreadID: 78443 Views:2612 Replies:12 FollowUps:13
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Over the last month or so , I've noticed that when I run "dry" on my main fuel tank and switch over onto the sub the gauge has been showing either 3/4's or 1/2 full....go into the petrol station and fill up...sure enough the sub tank is low as per fuel gauge.

has anyone else had this problem?

ps the sub isn't leaking.
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Reply By: Voxson - Thursday, May 13, 2010 at 16:57

Thursday, May 13, 2010 at 16:57
You are on your own at this stage...
Quite often i have tried puting fuel into my sub when i fill the main but it is chokkers.
AnswerID: 416545

Reply By: gazza414 - Thursday, May 13, 2010 at 17:00

Thursday, May 13, 2010 at 17:00
That's how mine used to be too!!!!!!!
AnswerID: 416546

Reply By: Baz&Pud (Tassie) - Thursday, May 13, 2010 at 17:12

Thursday, May 13, 2010 at 17:12
gazza414

We have a 02 V8 petrol and our sub tank has been "leaking" into the main tank since new.
Once i realised this was happening i complained to the tojo man prior to having the vehicle serviced and was told that it was the norm, i'm no mechanic and had to believe what i was told, going by the answer above it seems that it may be able to be rectified, would like to know how.
Cheers
Baz
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AnswerID: 416550

Follow Up By: gazza414 - Thursday, May 13, 2010 at 17:18

Thursday, May 13, 2010 at 17:18
Ya gotta laugh when they say normal ...ahhhh
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FollowupID: 686676

Reply By: Member - Andrew L (QLD) - Thursday, May 13, 2010 at 17:14

Thursday, May 13, 2010 at 17:14
Petrol or diesel?..

...and are parking it on a downhill slope for any duration, like overnight?
AnswerID: 416551

Follow Up By: gazza414 - Thursday, May 13, 2010 at 17:17

Thursday, May 13, 2010 at 17:17
Its a 2005 V8..the vehicle is now parked on a slope --ie left side of vehicle up, RHS down--over night...prob be about 200mm variation left to right

you may be onto something--please explain your reasoning ?
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FollowupID: 686675

Reply By: Member - Keith C (NSW) - Thursday, May 13, 2010 at 17:31

Thursday, May 13, 2010 at 17:31
Gazza,I've got an 80s 4.5 petrol,as I understand it from the handbook,each time the ignition is activated a small amount of fuel is transferred from the sub to the main tank.If I use the car a lot ,but only short trips,stop start,I can easily pump a few litres over between fills.Maybe they use the same system on the 100s.Good luck Keith C
AnswerID: 416555

Reply By: Stu & "Bob" - Thursday, May 13, 2010 at 18:05

Thursday, May 13, 2010 at 18:05
n the diesel version, a small amount of fuel is transferred into the sub tank when the engine is running from the pump return line. This is to help keep the system operational and also serves to remind the owner to use the sub tank from time to time.
AnswerID: 416558

Follow Up By: fisho64 - Thursday, May 13, 2010 at 18:21

Thursday, May 13, 2010 at 18:21
cant say Ive heard of that before? Our 100 is used mostly around town and we've never had fuel go from one to another, certainly not noticably?
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Follow Up By: GerryP - Thursday, May 13, 2010 at 22:47

Thursday, May 13, 2010 at 22:47
Ditto, never noticed anything like that at all. Suspect the changeover valve might be leaking or sticking on return return line side.

Gerry
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FollowupID: 686734

Follow Up By: Member - Prickle (SA) - Wednesday, May 19, 2010 at 22:13

Wednesday, May 19, 2010 at 22:13
Doesn't happen wtih mine. BUT the Nissan feeds from the reserve to the main every time it is turned on. So may be this is what you are thinking of.
Russ


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FollowupID: 687417

Follow Up By: get outmore - Thursday, May 20, 2010 at 06:02

Thursday, May 20, 2010 at 06:02
naa that aint so

diesals use 2 solonoids that if working correctly completly seperate the take and return for both tanks

the petrols work differently
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FollowupID: 687433

Reply By: fisho64 - Thursday, May 13, 2010 at 18:26

Thursday, May 13, 2010 at 18:26
Id hazard a guess and suggest that the fuel (Im picturing the setup) solenoid that swaps from one to other isnt switching completely, regardless of which its switched to.
In this case continuing to suck some from subtank as well as main even though its on main. All the fuel return is going to the proper place though and hence slowly transferring from subtank.
AnswerID: 416561

Follow Up By: gazza414 - Friday, May 14, 2010 at 06:45

Friday, May 14, 2010 at 06:45
If the solenoids were faulty then I see how this could happen
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FollowupID: 686746

Reply By: rumpig - Thursday, May 13, 2010 at 21:09

Thursday, May 13, 2010 at 21:09
i've had my sub tank get half filled up once, when i was stopped on a steepish hill for a period of time whilst i set up to winch out where i was. beforehand the sub tank was practically empty, then afterwards it read half full. i thought this strange but sure enough i drove around on the sub tank for a few more days using the fuel that had transferred.
i posted a question about what happened on LCOOL forum as i thought it shouldn't be possible, but replies there said it was "normal" for it to happen.
AnswerID: 416597

Reply By: Member - Phil G (SA) - Thursday, May 13, 2010 at 21:20

Thursday, May 13, 2010 at 21:20
I think you'll find that on all petrol Toyotas with twin tanks, there is a small amount of fuel transferred because there are two in-tank fuel pumps which should never be allowed to get dry.

The diesels do not do this because they don't have fuel pumps in the tanks.
AnswerID: 416601

Follow Up By: gazza414 - Friday, May 14, 2010 at 06:47

Friday, May 14, 2010 at 06:47
I run my main tank till it is dry--literally as the motor cuts out--or bucks and kicks, then I change over to the sub...I normally rack up 1000k's a week
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FollowupID: 686747

Follow Up By: Member - Phil G (SA) - Friday, May 14, 2010 at 15:45

Friday, May 14, 2010 at 15:45
Sure fire way to destroy your $$$ fuel pump in the tank - it relies on the petrol to stay cool.
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FollowupID: 686800

Follow Up By: gazza414 - Sunday, May 16, 2010 at 14:20

Sunday, May 16, 2010 at 14:20
Phil, only does for a moment when the tank runs dry--remember its not totally dry ( the internals of the pump) ..no harm done---agree they run in tank to keep them cool(er)!!!

I have run "intank" pumps external in other applications and they perform very well long term.
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FollowupID: 686989

Reply By: Tony MD - Thursday, May 13, 2010 at 22:12

Thursday, May 13, 2010 at 22:12
Gazza, I suggest the leak may be via the tank breather lines. I assume that in 'normal operation' you have fuel solenoids on both the flow and return lines which are simultaneously actuated when you select to run off the sub tank?
Pressure can be equalised between the two tanks by operating the solenoid a few times whilst running.
Also check for a block in the breather line at the fuel filler cap.
Cheers, Tony.
AnswerID: 416607

Follow Up By: gazza414 - Friday, May 14, 2010 at 06:50

Friday, May 14, 2010 at 06:50
The breather line might be the go


also what has changed I ask...always a good starting point when PROB RARES ITS UGLY HEAD.

in my case , i now commute up and down Macquarie Pass every day---hard, fast tight corners. and I park the car over night on a slope

I'll change the parking attitude of the car and see what happens...1 change at a time
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FollowupID: 686748

Reply By: gazza414 - Friday, May 14, 2010 at 06:51

Friday, May 14, 2010 at 06:51
thanks everyone for their input....I'll let you know how I get on
and if anyone else has some suggestions pls post.

thanks
AnswerID: 416622

Reply By: Member - Graham H (QLD) - Friday, May 14, 2010 at 09:09

Friday, May 14, 2010 at 09:09
Well my 2005TD Diesel doesnt do any of that I fill it to the top of the filler and run the main tank right down and the Sub is always full on the gauge.

My understanding is the two tanks are seperate and each feeds the engine but not each other.

A Patrol pumps the sub into the main tank but a Cruiser doesnt.


Mine has always been very slow to put the last 20litres into it Spits back and gurgles away. Have had the breathers checked but still does it.


Is the worst car I have ever had to fill the tanks on.
AnswerID: 416636

Follow Up By: Mikee5 (Logan QLD) - Friday, May 14, 2010 at 13:29

Friday, May 14, 2010 at 13:29
Hi Graham, I empty my sub tank first, which brings the weight of the fuel load forward of the rear axle. It may not be a big effect but I feel better. I also fill the two tanks about evenly, eg 20 litres into the front then 10 in the rear, this seems to reduce the burping. Cheers.
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FollowupID: 686787

Follow Up By: gazza414 - Sunday, May 16, 2010 at 04:16

Sunday, May 16, 2010 at 04:16
Thanks Graham, its interesting about the separate feeds...wonder how far up the system where the X over takes place before the line enters the fuel rail.
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FollowupID: 686940

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