Duel Fuel tank issues

[camspot Lurker Find all posts View Profile Close camspot]

Am currently experencing issues with the duel fuel tanks on the prado.
It is a 120 series 3L crd with 2 90L tanks.
Am wondering if any one knows wheather it draws fuel from both tanks all the time or if it draws from one tank being constantly topped up by the other?

The car is sucking air once it changes to the 2nd 90L tank and uses 1/4 of the fuel. If you top up the fuel it seems to run fine. I have put it down to a damaged (cracked or split) fuel pick up in one of the tanks, I am just not sure which tank.

I came to this conclusion by pressurising the the fuel lines from the suction side of the fuel filter back to the tank. There is no leaks in the fuel lines, but the fuel that is repressurised in the tank and forced back up the fuel line is full of air and is not a solid stream as I expected. Once I filed the tank and tried again there was a solid stream, concluding that there must be a problem with the pick up. Now I just need to work out which tank.

If any one has any info on how the fuel sys works I would appreciate some direction from here.

P.S. Have contacted several Toyota dealers that I thought would see a few of this model but they just dont seem to know much about the system.

Cheers

[Pedro Advanced Member Find all posts View Profile Close Pedro]

Hopefully PeteS will see this.
He has a diagram and explanation which i tried to find with no luck.
I will keep searching

[SWR Banned Find all posts View Profile Close SWR]

Hi camspot

Here is a few links that might help you with your problem!

http://www.pradopoint.com/showthread...m-diesel/page2

http://www.pradopoint.com/showthread...&daysprune=365

Also if you go to http://www.toyodiy.com/login?from=/ and open an account (It is free) keep your personal details to a minimum and DO NOT use your Vin number but track your vehicle by yr/make model etc.
You will then be able to look at every part with detailed diagrams of you vehicle

Cheers

[fridayman Senior Member Find all posts View Profile Close fridayman]

Why shouldn't he use the VIN number?

[SWR Banned Find all posts View Profile Close SWR]

Hi fridayman

You can use your vin number if you want to but you have to be aware that this sight is based in Russia (Land of corruption).

You could very well be ok but if your vin number was to get in the wrong hands Who knows?

You can easily track your vehicle model by picking year and model etc!

It is just a personal paranoia of mine concerning the world wide web when it comes to throwing personal details around (https means secure sight and http means not secure. The S is for encrypted connection).

Nothing really to be worried about but a good habit to adopt for safe web browsing.

Cheers

[fridayman Senior Member Find all posts View Profile Close fridayman]

Gotcha

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Fuel is pumped from the main tank to the injector pump, excess fuel flows back from the injector pump
to the main tank the via aux tank. Note the fuel does not actually empty into the aux tank
simply goes in and out through a coil, I assume this is to heat or cool the fuel that's in
the aux tank for some reason, most likely heat as if the aux is empty then it wouldn't
cool the fuel going through.

The the fuel returning from the injector pump via the aux passes through a venturi in the main
fuel tank. The venturi is used to suck fuel from the aux into the main. So basic answer is fuel returning
from the injector pump drives a venturi effect which is used to suck fuel from the aux, there is no
actual pump between the two tanks.

Interesting point of this setup is if the main is empty but the aux should be full there is no way to transfer
the fuel from the aux to the main.

Cheers
LeighW

[camspot Lurker Find all posts View Profile Close camspot]

Found this post; not sure if it was listed above too many tabs open.
Seems to match the problem perfectly so will drop the tank, check the pump and continue to troubleshoot.
Cheers all.

[Jack_ Lurker Find all posts View Profile Close Jack_]

Check that all the fuses are good to go, I had a similar issue:

http://www.pradopoint.com/showthread...out-of-factory

[awwricecracker Member Find all posts View Profile Close awwricecracker]

hopefully it took less than 4 years to sort out

[David the Viking Junior Member Find all posts View Profile Close David the Viking]

Is this another case of a blocked underbody fuel filter between the two fuel tanks inhibiting the transfer of fuel from the sub tank to the main? This would explain why it is ok when the fuel is topped up.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Is this another case of a blocked underbody fuel filter between the two fuel tanks inhibiting the transfer of fuel from the sub tank to the main? This would explain why it is ok when the fuel is topped up.

Who knows, the original post is 4 years old, the original poster hasn't visited the forum for over 2 years.............

Cheers Andrew

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

He could be still under the car working out how to put all that crap back into place.

[mackayvx Advanced Member Find all posts View Profile Close mackayvx]

There are 2 different systems for the fuel transfer between tanks on a 120.
A venturi set up on early kz 120's and the D4Ds are different but im not sure how.

The problem with my kz 120 was the in the fuel return banjo on the injector pump.
As leigh w said, this fuel return runs a venturi which actuates fuel transfer from the back to the front tank.
In the furl return line banjo is a spring and a steel plug - lets call it a cylindrical ball bearing ��

I replaced my whole return banjo assembly and the problem was fix. No further issues for 2 years now.
I am guessing the spring had lost tension and wasnt returning the fuel properly to run the venturi.
There is also a small gauze filter under the spring that can block up too effecting fuel return rate.

From memory it was like 15 buck from the diesel shop. They told me i was mad and my theory didn't make sense.

Other than that, pulling my tanks out twice and ripping my hair out didnt achieve anything.

[blackbird64 Junior Member Find all posts View Profile Close blackbird64]

Hi All PPers.
I know this thread is a bit old but i am a bit confused as to how the fuel system works on the dual tank setup. there is cobnflicting info here (on PP) about the operation of the fuel pump in the main tank.
it either
a) pumps fuel from the main tank to the small filter and back to the main tank to drive a venturi "syphon which pumps fuel to the aux and sucks fuel back (recirculating)
or
b) it pumps fuel to the primary filter under the bonnet with the return coming back to the Aux Tank.

So my problem is this :
2008 GXL diesel Prado (150000Kms). always serviced meticulously but on a long drive the car just died on the side of the highway with about 30litres remain in the aux tank. anyhow put in 20litres . reprimed and away we go. hmm
Mr. NRMA came and primed the fuel filter and it ran for a very short time before dying again.


So my gut instinct and logic is that the aux tank pickup must be cracked / holed up to the 30 litre high water mark, thjis means that it will suck air rather than fuel and since the engine draws fuel only from the main tank (till its empty) then the aux is pulled into the main tank .

So i think i need to drop the aux tank and maybe replace the pickup/sender unit ?
is this right ?
Regds Blackie