2021 Prado 150 double fuel tank issue (Fuel Filter Maintenance Required) (1 Viewer)

[pmrosendo]

I've installed a OEM secondary fuel tank to this European (AdBlue, Euro6) TOYOTA LAND-CRUISER Prado 150, using a lot of information collected here and several other places on the Internet.

The system uses the OEM fuel tank with a different fuel pump/level sender and the secondary fuel tank, also OEM, with just the level sender added to the circuit in parallel connection with the existing wiring. There is a new electrical fuel pump, inside the main tank, that is used for the Venturi effect, in order to pass fuel from the additional tank to the main tank.

I didn´t find the correct electrical schematic to connect this new electrical fuel pump so I did a analog connection, using a relay that only has the fuel pump working if the engine is running.

I used this schematic to order all parts and respective connections, it's pretty much "plug 'n play" with some minor modifications to some tubes, specially on the engine and return fuel connections, in order to use the existing connecting points that have small differences, maybe due to this car being an European version of the Prado 150.

Again I have to thank the ih8mud.com forums to point me out the right way of performing this modification.

Everything works perfectly fine, the fuel gauge works perfectly, it reads the fuel quantity in both fuel tanks, and goes from top to bottom after consuming the 150L of fuel capacity now available.
It lights up the reserve light within expected gauge position and it's quite accurate on it's position, displaying the remaining fuel quantity in both tanks.

After refuelling, it takes 30 seconds to display the expected autonomy and here we have a problem!!! It does not display more than 550 kms of autonomy, even with 150L of fuel capacity full of fuel. What it does is decreasing 1 or 2 kms per 5 or 6 driven, assuming different autonomies randomly.

The main issue is when you drive constantly (cruise-control) at more than 120 kms/h and suddendly this message comes up...

I've replaced the Fuel filter, reset the message and if driven under 120 kms/h, everything is normal, no message whatsoever.

After driving for at least 25 kms above 120 kms/h, this message comes up and only resetting the fuel filter will it disappear...
The car drives normally to 180 kms/h, without any issue, no power lost, other than this message, so I believe not to be a short fuel debit to the engine, but...

I think that this problem is only a gauge/message issue, due to not having the new correct fuel capacity (150L) on the software system of the car, on the gauges, since the car only had a 87L fuel tank and now has an 87L plus a 63L additional tank.

This post is to ask for help on this subject, since this is a very annoying issue...

Thank you in advance.

 

[r2m]

Wonder if the there's a problem with the float, the arm that raises and lowers depending upon how much fuel is in the tank.
If the arm isn't going all the way up, it will only show on your dash whatever height the flow will move up to.

 

[pmrosendo]

Wonder if the there's a problem with the float, the arm that raises and lowers depending upon how much fuel is in the tank.
If the arm isn't going all the way up, it will only show on your dash whatever height the flow will move up to.

Both arms are brand new, since I had to replace the OEM fuel sender with a new one including the electric pump and the rear additional tank is also brand new, including a new fuel sender.

Parts replaced/added:

77010-60191 (from factory) to 77020-60470 (new one with the 23220-30011 electric pump as the main difference);
77001-60730 (new additional tank) and 77010-60240 (fuel sender unit).

 

[ericm979]

Maybe the fuel filter message is due to the injection pump not seeing enough pressure from the tanks. That would make it think the filter's clogged. Do you have access to an OBD2 reader, or Techstream? You can scan for codes and possibly monitor the fuel pressure between the tanks and injection pump. I'm assuming there is a pressure sensor there but I can't think of any other way they'd measure the fuel filter effectiveness in order to put up the warning.

The plumbing could be wrong, or a pump defective, or a fuel pickup or line damaged.

 

[pmrosendo]

Maybe the fuel filter message is due to the injection pump not seeing enough pressure from the tanks. That would make it think the filter's clogged. Do you have access to an OBD2 reader, or Techstream? You can scan for codes and possibly monitor the fuel pressure between the tanks and injection pump. I'm assuming there is a pressure sensor there but I can't think of any other way they'd measure the fuel filter effectiveness in order to put up the warning.

The plumbing could be wrong, or a pump defective, or a fuel pickup or line damaged.

I'll have to get a TECHSTREAM in order to figure out what's wrong.

I think it's only an electronic issue, due to the gauges not having the correct settings, however I must consider all suggestions.

 

[pmrosendo]

I'll have to get a TECHSTREAM in order to figure out what's wrong.

I think it's only an electronic issue, due to the gauges not having the correct settings, however I must consider all suggestions.

I have some update on this matter.

TOYOTA told me that the fuel filter is different in the same model, depending if it has or not, double fuel tank.
I will replace the existing filter with the new one (part# 23390-36760) and test it to find out if the problem is solved.