Factory sub tank - sourcing and fitment discussion (2 Viewers)

[grinchy]

I estimate that three gallons are used before the needle moves below Full. Conveniently this is also the rough offset in the gauge reading at sub empty as well. I’m thinking of adding another 15 ohm in series and seeing that does, it may scale back perfectly. I found a couple potentiometers in my parts box, maybe the real answer here is just swapping those into the sender network and dialing in the solution.

 

[TLCLVR]

Found on youtube the original (aussie version) of LRA install video from 7 years ago. It has the same filler that I tried to retrofit as standard equipment. Rather than do the body lift, they suggest bending the vent tube more inline to get the factory filler out (in a later step they cut this off, so it works in that install fine to bend it, as it is later cut off). That is good to know! At least we now know that to fit that version (the ROW spec filler, with or without sub tank bung), it would require the body lift or a modification to the vent tube angle. There is NO jenga jenga jenga that will fit it thru the clearances.

Bending the vent tube, particularly with a appropriate support, may be a viable alternative to the body lift . . .

I leave it to the next adopter to try

Wow @grinchy! You've outdone yourself! Thanks for trailblazing for the rest of us. Though I must admit I read through this in one sitting today and you may have cured me of my desire to DIY a sub-tank (at least for the time being )

Not having disassembled this portion of my LX this is a total shot in the dark, but is there any chance the plastic faring around the filler pipe inlet can be removed, and the new filler pipe fished in from the top? Without the hassle of the body lift?

 

[grinchy]

Wow @grinchy! You've outdone yourself! Thanks for trailblazing for the rest of us. Though I must admit I read through this in one sitting today and you may have cured me of my desire to DIY a sub-tank (at least for the time being )

Not having disassembled this portion of my LX this is a total shot in the dark, but is there any chance the plastic faring around the filler pipe inlet can be removed, and the new filler pipe fished in from the top? Without the hassle of the body lift?

View attachment 2639252

It's not so bad. You could do it in a long weekend I think. Each individual task is very approachable!

This wouldn't work. Think of the filler neck as a 3D piece that has bends going both up and right. So any time you spin it to accomodate for 'up' the 'right' bend will move either up or down, and so on. The clearance pinch(es) are the crossmember at the rear axle and the body above, and the body gap where the filler goes between body and frame up to the neck.

I did pull that rubber piece out and replace it (so shiny and new), but this didn't get any additional access or room for the jenga jenga jenga. The limiting factors are the associated filler tube vent pipe, which juts out quite far on the sub tank filler, and the pinch points. So one can increase the pinch points (body lift) or one can 'bend' the new vent tube to not jut as much from the main filler tube (which is way easier and I suggest people try, probably only need to narrow the gap by 1"). That said, the body lift (as long as you do all nine bolts) isn't in any way technical, you don't even take the nuts off, just loosen. Lift. Slide the filler in. unlift. and retorque. Getting to the bolts is just seats and interior part removal.

 

[grinchy]

Another fill-up today. Was at 1/4 on fuel gauge, put in 28.9 gallons. 1/4 on gauge should be 9 gallons remaining, actual capacity remaining was 7.5 gallons, so about 1.5 gallon differenc. This fill I'll run down to 1/8 tank and see what the actual fill volume will be for that reading.

Fill-up had no clickoffs, working perfect still as far as venting. It took long enough to put in that much volume that I had time to clean all the windows.

I've had zero evap codes so far . . . .

 

[Whiskerz]

Thanks for doing this

 

[grinchy]

Was running the tank down to 1/8. Got it down to one tick above 1/8. Had a crank start stall no DTC. Put in 2 gallons. Had a crank start stall. Put in 2 more gallons. Had a crank start stall. Fuel level now nearly to 1/4.

Cleaned the MAF. Immediate start.
Went and filled it up (26.6 + 4) -> 30.6 gallons. First click registered just below F. i don't ever fill past the pump click off. But in this case I figure I left 1 gallon short of all the way full. (31.6), so about 5 gallons should have been in the tanks.

I'm not sure what was up - could have been a dirty MAF, could have been a fuel issue. The way it stalled it seemed it was getting fuel pressure (because it started). I'll keep an eye on it and report back. Still need to do the volumes testing there closer to an empty tank (need to test 1/8 and E/light).

Near 1/8th with a full fill 31.6 (ish). Calculated value for 1/8 is 4.6 gal, so sender seems pretty accurate on this reading. Within a gallon or so.

So, now have to burn off another 300 miles of fuel thru driving and then empirical testing can continue.

 

[grinchy]

Car continues to start, so leaning toward dirty MAF.
Will be watching when fuel gauge gets down to 1/4 tank again.

 

[S.CarolinaFZJ80]

@grinchy
Eagerly reading through this thread. I justly picked up an '18 200 and would like to add this OEM sub tank.
I did a full OEM retro fit in my 80 about 11 years ago now and love the extra range.
The 200 definitely needs it.

I didn't see it mentioned here though... does the factory ECU control the transfer?

In the 80, and external ECU is triggered manually by depressing a switch. The ECU controls the transfer and will stop it once the main tank reaches 3/4 full, as to not over fill.

This separate quantity switch needed to be added to the main tank. The ECU also shuts off the transfer when battery voltage gets too low.

From what I am reading, the 200 just uses motive flow to transfer from the aux to the main. Is this loop always open?

 

[grinchy]

@grinchy
Eagerly reading through this thread. I justly picked up an '18 200 and would like to add this OEM sub tank.
I did a full OEM retro fit in my 80 about 11 years ago now and love the extra range.
The 200 definitely needs it.

I didn't see it mentioned here though... does the factory ECU control the transfer?

In the 80, and external ECU is triggered manually by depressing a switch. The ECU controls the transfer and will stop it once the main tank reaches 3/4 full, as to not over fill.

This separate quantity switch needed to be added to the main tank. The ECU also shuts off the transfer when battery voltage gets too low.

From what I am reading, the 200 just uses motive flow to transfer from the aux to the main. Is this loop always open?

Fuel flow from the sub tank is pumped over via a Venturi vacuum created when the main tank fuel pump is running.
So you get a few parts and update the main tank fuel assembly, or you buy a new main tank fuel pump assembly and swap it. It’s cheaper to buy the parts, but easier to buy the assembly.
There is no active pump on the sub tank, just a pipe attached to the Venturi from the main.
There is a sender in the sub tank, so you can read that fuel level separately

 

[S.CarolinaFZJ80]

Thanks @grinchy
Appreciate your reply.

So with your set up, does it operate as described in the highlighted text from this post for an Australian forum?

It seems as the 1/2 tank quantity that triggers the light and gauge switch over might also reset the range computer. As I can't imagine the factory set up showing zero range

 

[grinchy]

Thanks @grinchy
Appreciate your reply.

So with your set up, does it operate as described in the highlighted text from this post for an Australian forum?
View attachment 2759489

It seems as the 1/2 tank quantity that triggers the light and gauge switch over might also reset the range computer. As I can't imagine the factory set up showing zero range

No, the combination meter (gauge cluster) on the us models does not manage two fuel tanks. The part numbers are different. There are several options:
Hook the two senders to a two way switch and read whichever you want via switch
Hook the two senders into a parallel resistor series and read both volumes at once (what I did)
get a fuel gauge combiner
Mount a separate fuel meter for the second tank somehere
Just roll with the stock sender, the sub tank always empties first so . . .
Right now my resistor network isn’t quite right and I run out of gas around 1/8 tank. I mean to get around to fixing it but it’s summer

 

[S.CarolinaFZJ80]

No, the combination meter (gauge cluster) on the us models does not manage two fuel tanks. The part numbers are different. There are several options:
Hook the two senders to a two way switch and read whichever you want via switch
Hook the two senders into a parallel resistor series and read both volumes at once (what I did)
get a fuel gauge combiner
Mount a separate fuel meter for the second tank somehere
Just roll with the stock sender, the sub tank always empties first so . . .
Right now my resistor network isn’t quite right and I run out of gas around 1/8 tank. I mean to get around to fixing it but it’s summer

Ahh, Ok so the gauge cluster in some foreign models handles the switching.

Wonder if in my case, it might be easier to have both senders independent using a switch do show main vs sub quantity (when needed).

I wonder if there are any unused icons on the US cluster that can be repurposed as a graphic indication that the it's reading "sub" quantity.

I found a switch that might work for this purpose.

 

[grinchy]

Yeah, that looks like a good switch if you want to toggle between tanks.
Functionally I don’t think I’ve ever been confused on about how much fuel is in the sub tank, but I suppose if you want to know having the capability is good.
I went way out of the way to merge the gauge reading and I am going to go to switched. I’d actually be fine on main only anyway, reality is that knowing the last 24 gallons is plenty of warning of an impending empty.

 

[Toyoland66]

Ahh, Ok so the gauge cluster in some foreign models handles the switching.

Wonder if in my case, it might be easier to have both senders independent using a switch do show main vs sub quantity (when needed).

I wonder if there are any unused icons on the US cluster that can be repurposed as a graphic indication that the it's reading "sub" quantity.

I found a switch that might work for this purpose.
View attachment 2760104

I was planning on this approach prior to seeing how @grinchy did his with resistors.

You can get a double pole double throw switch, I had to do some research on part numbers because Carlisle has a bunch of options for the wiring, backlight, momentary, and what up middle and down do on the switch. You want a non momentary switch with only up and down with no stop in the middle if that makes sense. I can dig up the part number I used if you are interested.

I also had a custom switch cover made to indicate if it’s switched to main or sub tank.

 

[S.CarolinaFZJ80]

I was planning on this approach prior to seeing how @grinchy did his with resistors.

You can get a double pole double throw switch, I had to do some research on part numbers because Carlisle has a bunch of options for the wiring, backlight, momentary, and what up middle and down do on the switch. You want a non momentary switch with only up and down with no stop in the middle if that makes sense. I can dig up the part number I used if you are interested.

I also had a custom switch cover made to indicate if it’s switched to main or sub tank.

Thanks @toyland66
I'd be interested in reading about it. I too like the simplicity of using one gauge with no switch but it doesn't look like it is dialed in yet. Having an accurate gauge is paramount.

 

[Toyoland66]

Here is the rocker switch I ordered. The 200 switch holes might be a different size

Dirty Parts

dirtyparts.com

This spec sheet decodes the part number

https://rockerswitchpros.com/wp-content/uploads/2015/01/V-Series_Spec_Sheet_full_RSP.pdf

I got the switch plate custom engraved

 

[S.CarolinaFZJ80]

I believe that @cruiserdan used an 80 series rear heater rocker switch and diode(s) to achieve the same thing in his 80 series along time ago.

 

[cruiserdan]

I believe that @cruiserdan used an 80 series rear heater rocker switch and diode(s) to achieve the same thing in his 80 series along time ago.

No diodes. I broke open the ground circuit in the switch and RE-wired it

 

[TheIcemanCometh]

Pulled the charcoal canister ...

Tonight I crawled under my LC to take look at what was above the spare wheel. So there is both the Fuel Evaporative Canister Filter and the Charcoal Canister Filter. In your LX you had to relocate both. For an LC the Fuel Evaporative Canister Filter is easily relocated. For an LC would the Charcoal Canister Filter also need to be relocated? You did lots of work to relocate yours.

What I am trying to suss out is IIRC for the LRA neither have to be relocated. Where are these located for European LCs?

 

[grinchy]

An tlc would just move the canister and filter to the wing. The LX has the AHC pump and reservoir in the wing already, so the relo would be to the front of the main fuel tank or the engine bay. The ROW fuel canister is located in front of the main tank.
I liked having the canister above the main fuel tank level, so of to the engine bay it went. Many other cars on the road have the canister in the engine bay. To do it again I’d use the existing tubing to burn off fumes for the connection and it would be a simpler relo.