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Discussion Starter #124
Electrical.....Auto Fill 1

Finally had some time to finish up the 'automatic mode' wiring and got it to work! If you go back and read starting at post#11 you can see where I first described this function and my early investigations on how it works.


A little back-story: The Toyota main tank sending unit produces a descending analog voltage reading ranging from 7V to 0V. Meaning it reads 7V when the tank is empty and 0V when the tank is full. Most manufactures use an ascending voltage sending unit that varies from 0V at empty to 5V at full. Theoretically, the APEXUS switch should be able to handle either one, but after speaking with the engineer at APEXUS (back in June 2018) he indicated that they had not done a lot of testing on the descending signal and couldn't guarantee it would be stable. I'm assuming they will eventually improve this and you won't have to worry about converting the voltage like I decided to do.​

Based on the above, and because it seemed like an interesting challenge, I decided to build a voltage converter so the switch would see a 0-5V ascending signal. The input of the converter connects to the Violet/White Fuel gauge wire on connector E13 (shown below) and the output connects to the White/Black wire on the switch. After a few attempts I finally got the converter right, and once I knew the signal to the switch was good, programming it was relatively easy. I've had it connected for a couple of weeks now and the switch has been turning the pump on and off automatically, based on my settings, very consistently. I'll share a few tips on programming in my next post.

Below are pictures of one of my prototype converters, the connection wire for the main gauge, and a rough schematic for wiring the switch.
 

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I'm curious about the details of voltage converter. Did you have to account for 0 volts also meaning no power coming in (besides full tank). I noticed your original attempt only included 1 cap. I see at least 4 on the new circuit. Just curious.
 

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Discussion Starter #126
Electrical.....Auto Fill 2 - Programming

Programming the switch is pretty straight forward but there are a few things to be aware of to make it easier and set it where you want it.

  • Make sure the engine is running when you program your setpoints. The voltage on all the circuits in your truck changes somewhat depending on whether the alternator is working. If you program your setpoints with the engine off you'll find you get different behavior when you're driving around.
  • The switch has very little to no hysteresis built into it. This means it is does not average/smooth out the signal from the main tank when the fuel is sloshing around a lot. It is reading the real time voltage from the main tank and as soon as the signal hits one of your setpoints it will turn the pump on or off. So, you may see the pump turn on/off earlier than expected when going around a sharp corner or up a steep hill.
  • The main tank fuel gauge on your dash has a LOT of hysteresis built into it. What you see on the dash may lag the actual tank level by 5-10min's. I'm sure all of you have seen where the gauge reads one setting when you stop somewhere and the next time you start the truck the gauge has dropped by 1/8-tank. So, if you're trying to be specific on your setpoint make sure its been sitting or idling for 5-10 min's before you program the setpoint.
  • Every time you turn the vehicle on, if the main tank is below the bottom setpoint it will turn the pump on; even if the aux tank is reading empty. With all the other features APEXUS has packed into this switch I was a little disappointed they missed this one. You would think they would know the aux tank level and prevent the pump from running if it is already empty. But, I guess you can't have everything and there is an easy way around it in the programming hints below.

Programming instructions/tips: Instruction manual is attached below.

Go to page 4 of the manual to start the programming steps. Some of the descriptions and pictures took a few minutes to decipher so here is a clear step-by-step method to get it setup.

1) First step is to fill the aux tank with at least 15 gallons, I'll explain why below.
2) Then drive around until your MAIN tank is a little below where you want your bottom setpoint. As mentioned above, since the switch doesn't have a lot of hysteresis, more often than not the pump will turn on a little earlier than expected.
3) Let the truck sit for a little while just to make sure your main gauge has caught up with the actual level in the tank. If it is too low you can manually run the pump to transfer a little more gas into the main tank.


4) Press the switch button 4x in 2 sec.'s. (Don't worry if you hear the pump start while doing this, it will turn off when you are in program mode.)
Switch will beep and the amber lamp will blink once indicating you are in Program Mode.
The 2 bottom green lights will be on indicating the "Run-after-Empty timer" is set to 2 minutes (this is the default setting if you haven't already programmed it to something else.)
You have 10 seconds to adjust this timer.​
5) Press the button slowly (press, wait 2 seconds, press again, etc.) until the lights cycle to just the bottom red light.
This indicates the "Run-after-Empty timer" is set to 0.
The pump will stop running immediately when the aux-tank is empty.
This will prevent the pump from running when you aux tank is empty and the main tank is below the set point (Issue D above). It also help in general to prevent the pump from ever running dry.​


6) Wait 10 sec.'s.
Switch will beep and the yellow light will blink twice.
This indicates you are ready to program your setpoints.​
7) Press the button slowly (press, wait 2 seconds, press again, etc.) until the bottom green light is blinking
The top green light will be on steady
The bottom red light will be on if the setpoint has not been programmed.​
8) Press the button 2x in 1/2 sec. to program the bottom setpoint.
The red light will turn off indicating the setpoint has been programmed.
If the red light was off to begin with pressing the button twice will clear the setting and turn the red light on. Press it twice again to reprogram it. (This is different than the instruction manual that tells you to press it 5x to clear a setpoint)​


9) Exit programming mode so you can fill the tank to the upper setpoint.
Wait 10 sec.'s
Switch will beep and the yellow light will blink three times indicating you are in the last programming stage. This is not used, don't do anything here.
Wait 10 sec.'s again.
Switch will beep again and return to normal operation mode.​
10) Fill the main tank to the desired level where you want the pump to turn off.
This is where I just ran the pump and transferred fuel from the aux tank to the main tank.
I ran the pump for 20-mins to transfer ~10 gallons (Pump runs at 2-liters/min).
If you're using the main fuel gauge to check fill level remember the hysteresis mentioned above and give it 5-10 minutes to ensure you have the right reading.​


11) Re-Enter program mode to program the upper setpoint.
Press the switch button 4x in 2 sec.'s. Switch will beep and the amber lamp will blink once.
Wait 10 sec.'s. to bypass timer setting. Switch will beep and the yellow light will blink twice.
12) Press the button slowly (press, wait 2 seconds, press again, etc.) until the top green light is blinking
The bottom green light will be on steady
The bottom red light will be on if the setpoint has not been programmed.​
13) Press the button 2x in 1/2 sec. to program the top setpoint.
The red light will turn off indicating the setpoint has been programmed.
If the red light was off to begin with pressing the button twice will clear the setting and turn the red light on. Press it twice again to reprogram it. (This is different than the instruction manual that tells you to press it 5x to clear a setpoint)​
14) Return to normal operation mode.
Wait 10 sec.'s
Switch will beep and return to normal operation mode. You do not have to wait for the 3rd stage because it is not used when both setpoints are programmed.​

Enjoy your auto-fill function!
 

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Discussion Starter #127
I'm curious about the details of voltage converter. Did you have to account for 0 volts also meaning no power coming in (besides full tank). I noticed your original attempt only included 1 cap. I see at least 4 on the new circuit. Just curious.
Final design actually has 5 caps, but I forgot to take a picture of that board before I buried it in my dash. I didn't specifically take into account the 0-power state as I figure that would only occur when the system is entirely shut down anyway.
 

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Fantastic C Ray!!

Can you post the schematic of your voltage inverter too? I think your whole design looks very straightforward and would make living with an AUX tank even that much more nice to live with.

Norm "little tank" Kerr
 

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Final design actually has 5 caps, but I forgot to take a picture of that board before I buried it in my dash. I didn't specifically take into account the 0-power state as I figure that would only occur when the system is entirely shut down anyway.

Your picture does show five caps. I just didn’t count all of them. Great work.
 

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Sweet and congrats!

Too bad they don't offer a short but still increased capacity version to allow room to squeeze in a TacoBox.
 

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Discussion Starter #133
Since @DucRider asked, I thought it would be helpful to post a consolidated list of the extra parts I bought to adapt the LRA tank to a U.S. spec FJ.

I hope I didn't blow the fitment issues out of proportion in my write-up, I expect companies to represent their product correctly, but in the end it was only about $100 in parts and a little extra hassle. I couldn't be happier with the results I've gotten and the improvement it has made.


Consolidated Parts List:

Additional fuel lines
Filler Neck Supply Co.
https://www.fillernecksupply.com/

Qty 1 B01 1-1/4" To 1" Rubber Fuel Hose End ID Reducer.
Qty 36 D138S 1-3/8" Inch (SOFT WALL) Gas, Oil, Diesel Fuel Filler Hose (SOLD PER INCH) (I used 27” of this)
Qty 40 27068 Gates 1/4 Inch Fuel And Filler Neck Hose (SOLD BY THE INCH) (I used 39” of this)
These were for the sections of hard pipe I made so I didn’t have to cut my OEM filler tubes. Now that I know how it all works, I wouldn’t be afraid to cut the OEM filler tubes so I could reuse the stock mounting brackets. So these parts are optional.
Additional Hose clamps
Additional elbow needed for the main tank overflow tube
Breather for the charcoal canister. I connected this with some spare 3/8 tubing I had and a couple 3/8 barb couplings (like this)

TOTAL for everything above was $102

I also wrapped the exhaust where it was near the tank, just for good measure.
Finally, you might consider beefing up the rear springs. If you have a lift, this is the set to get. You’re adding several hundred pounds behind the rear axle when the tank is full, which will drop the rear by an inch or more with stock rate springs.

Electrical parts you’ll have to figure out on your own. I didn’t keep track of what I used as I have all the wire, relays, shrink tubing and other materials on hand. In my opinion, solder and shrink every splice, route your wires where they won’t get damaged, and make sure you use the proper gauge. If you’re not already good at wiring, find someone who is so this won’t quit working unexpectedly when you’re a long way from nowhere.

Below are the reference pictures for where the parts were used:
 

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there is a good reason why:

Due to the packaging space, the aux tank cannot be installed in line like the sketch shows, so some of the fluid will have to be made to flow uphill (both for filling and for fuel transfer between the tanks).


Note that a larger main tank, available from the same supplier, does make it this simple, because it is all in one large tank. But for the same money, less volume is gained (again, due to packaging limitations).


So, the filler neck is necessary to split, to be able to fill both tanks, and the pump is necessary in the "filler line" (as labeled in the sketch above) to transfer it back.



Note that there are super simple aux tanks with their own filler neck, but that is a pain to fill (need to move the filler nozzle), and has to vent to atmosphere (gas smell in the garage). Also, simple rotopax tanks are even simpler, but they require manual filling and require stopping and manual pouring to use.


N
 

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This whole setup seems overly complex. Is there any good reason that auxiliary tanks are not just connected like this (no separate filler line, no transfer pump, etc):
That lower connector between the tanks would have to hop over the rear axle, would limit how much could get out of the aux tank.
 
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