Prado fuel gauge

Scott,

I have a 120series 04 Gxl and mine does the same. On the first tank the needle only goes back to halfway and this takes about 700-750 kilometres of highway driving. It will then change to the second tank which as you know is indicated by the 90L light.
I dont know whether you know or not but there is also a dedicated prado owners website at www.pradopoint.com
You may get more info from there.

Cheers

Dave

Scott,
My brand new (06) one threw me when it first did it. Fill the tanks and get to the half way mark and the tank goes back to full but the 90L light comes on. I ended up ringing Toyota dealership, looked like a bit of a dipsh@t i suppose but got the answer straight up. Refreshing to only use about half of what i would have in my Patrol petrol $$$$.

Yeah, that's the way it works as per my 2005 120 series diesel manual. The 1/2 way down on the guage the first time means 1/2 of the 180 total fule capacity has been used (i.e. about 90 litres). Similarly the 1/4 way mark means 1/4 of the total capacity or 1/2 the first tank has been used (i.e. about 45 litres).
When it changes to the second tank the green 90 litre sign goes on and the guage goes back to the top saying you now have available all of your second 90 litre tank. When that goes down to half way it means you have used 1/2 of your second tank and now have only about 45 litres of fuel left.
Now we are probablyt all confused.
I guess this gives a more accurate reading for the second tank than for the first tank full (twice the scale). One soon gets used to it.
The bad aspect from my point of view is that it is not possible to manually switch from tank 1 to tank 2 (what if it goes wrong and doesn't switch automatically? What if one tank gets a hole or leak in it? - the sytem just keeps pumping both tanks out).
Our last 4WD had and electric switch to go from one tank to the other, and the one fuel guage (after a short delay) showed what one had in whichever tank one was switched to. And the fuel lines were independent of each other. I liked that better.
Enjoy! de Rob.

DaveNQ's description of the gauge logic is correct.

Arkay, there is no switching between tanks anymore (hence nothing to go wrong mechanically). All fuel is drawn from the main tank to the engine.

What now happens is whenever there is fuel in the sub-tank (and the engine is running), it is continuously transferred to the main tank to keep it full. This is done by means of an ejector (jet) pump, which uses excess fuel returned from the fuel pump to pass through a venturi, creating suction and drawing the fuel from the sub-tank into the main.

Because there are no moving parts, there is nothing to wear out or malfunction, such as valves and solenoids.

Having said that, I'd still prefer to be able to control which tank I draw fuel from :-)

All working as designed.... My problem is I removed the rear tank to fit LPG
and when gauge showing half full, I only used about 25 liters.. and the red
light comes up when I got about 40liters in fuel tank left...

Thanks heaps for your time to respond .
My wife and I' are (were) sure that the first tank went all the way to empty before it switched over because we "thought " we used to watch how close to "E" it got before it switched to the second tank. Now I'm not as confident that this was the case. Could be time to consider appolagising to the young wan-er at Toyota that I gave a mouthful to for about 10mins last time I was there. Maybe his attitude was only a reflection of mine. Oh well I will be back there in a couple of weeks.

Cheers
Scott