Possible Dual Tank Issue

[topic97 Senior Member Find all posts View Profile Close topic97]

Hey guys, I just bought my first prado on the weekend, so be kind if this has been asked before, but I couldn't find any info.

When I bought it, the previous owner had already filled it up, but not sure how many k's he did before I took ownership of it.
But I drove it back from Melbourne to Bendigo & have been doing a few ks around town since & hit about half a tank tonight after having done about 360ks.

I parked it for a bit tonight & it was just a smidge above half on the first tank, then when I got back in it had jumped over onto the reserve tank.

So I drove it into a servo just so I could fill it up and see how much I get of a full fill, but it only took 67 litres - shouldn't it have taken 90?

Its a Prado Grande 120 series V6, so im assuming that it has the 180L fuel tank.

Do I have a possible issue here, or is there some funky way that the dual tank setup works that im missing?
Just trying to get my head around how these cars work - dont want to get stuck out whoop whoop thinking i have more fuel than I actually do!

[Guest Close Guest]

The fuel gauge isn't exactly accurate. So now that you have filled it up to full, run the tank empty and see how it goes. Expect about 1100km on full tanks. Might be more if it is completely standard and you aren't doing short trips.

[topic97 Senior Member Find all posts View Profile Close topic97]

Yeah that's what I think ill do now. Thanks mate.
Its odd though, I would have thought if it only just switched over to the reserve tank, shouldn't it have taken 90 litres?
Or do they keep pumping fuel from the first 90 into the reserve once they switch over?

Just trying to get my head around how it works! lol

[topic97 Senior Member Find all posts View Profile Close topic97]

Ok, so I'm semi-convinced something is going on.

So recapping, When my gauge hit the start of the second 90l, I filled it up again & could only manage to squeeze about 65litres into it - so I assume both tanks are full.

The first tank, I got only about 360ks out of until it switched over on to the second tank.

I have been cruising around today and its been sitting pretty much on full until tonight, I jumped into it after work, was still just under the full mark.
I then picked the little one up from creche and it was parked on a decent downhill decline, so when I started up it it was showing just over 2/3 on the second 90l.

Picked up my other daughter from school & it was sitting on a flat decline and now its sitting only a smidge above half tank on the second 90l & I have only done 80ks on the second tank and 440ish all up!!

Does anyone have any idea what the hell might be happening?
The on board data of the Grande is showing me 15.3l per 100k which is not too bad and probably about right, but according to the fuel gauge im not going to get anywhere near 600ks to a tank!!

Help!!

[Guest Close Guest]

Have you checked underneath to see if you've got twin tanks?

[topic97 Senior Member Find all posts View Profile Close topic97]

Yeah, one at the rear & one on the passenger side.

Jumped in it this morning and it was back up to a smidge over the full mark on the 90l, then did the school drop off, went to get stuff for work at the supermarket and it dropped down between the 3/4 and full marks.

Buggered if I know what's going on.
I know they aren't fuel efficient, but I just don't want to get stuck out the back of nowhere on my travels thinking I have more fuel than I actually do!!


Is it possible that the fuel is transferring between tanks when its resting? Or does the transfer only work from the secondary to the main tank?

[Guest Close Guest]

The fuel is constantly being transferred from the rear tank to the front tank. Might just be a fuel gauge issue.

[topic97 Senior Member Find all posts View Profile Close topic97]

Yeah, sounds like it.... perhaps its time to get a new sender and see how that goes.
I'm gonna do a few full fills and see what happens - hopefully ill be able to gauge how much is left by the consumption.
Just would be nice to know exactly how much is in it! lol

So the fuel transfer, is that done via pump or gravity? As in, if it switches on the gauge from the first to second tank, will it still transfer from the other tank if there is fuel in it?

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

When parked on a hill mine will change the apparent fuel level.