Big Fuel Tank

[Akella]

Are there any more of the dual necks? If so, PM me the details please, someone, anyone, Bueller, Bueller.......

Nice pictures! As for the dual filler here is my sale thread: ForSale: BRAND NEW Dual Filler necks for 80 series. Only 1 left now.

The mounts for the front are best approached from above...I drilled holes from the top for those based on the comments of CruiserDrew, thus skipped doing the nutserts there. The holes look large, as they are "access" holes for the socket so that I could get to the factory holes below. Good old nuts and bolts for the front mount points, plus 25mm body plugs above, and nutserts for the rear.

Good ideal, i thought how fun it will be to drill above the axle.

I did note the external pump used for the OEM and many installs, along with yours. I'm actually leaning toward an in-tank pump myself to minimize and neaten the plumbing and wiring associated with the install. Most of the aftermarket tank options I cited previously support this, too. I used to be leery of in-tank pumps years ago, but they seem to have certain advantages, one of which being bathed in gas inside the tank will be in a cleaner environment than sitting naked to elements under the back of an 80.

I like the idea of in tank pump, but it wont be cheap even aftermarket.

I was thinking manual transfer with a spring-loaded switch. I'd get pretty tired of that after 15 or 20 minutes, but automating that is something that I think George's ECU will make simple -- at least it will when I get the time to digest everything.

Did you pm George about his ECU?

 

[greentruck]

On the non-OEM in-tank pump, I did see they run around $200. That may make some Toyota parts cost effective...

Nope, haven't emailed George yet. I want to get a handle on things before doing so. My quick impression so far is that George's ECU has the objective of providing similar to OEM funtionality, i.e. it automates the subtank-to-main transfer and idiot-proofs the process. And I may end up deciding that's the way to go.

But UI was actually thinking of doing things very simple and making the transfer manual. The issue I can think of with that is knowing when to turn off the subtank pump. Running it to empty/dry repeatedly is probably not a good idea. That alone may prove to be a sticking point, depending on the specs of the in-tank pump.

Overfill, i.e. pumping the subtank into the main while the main is still too full to accept it could be a problem with a manual fill, but the reference or two I've seen so far is that people seem to think it'll just go back to the subtank via the fill -- but that's just people talking, I don't know that's the case.

If it turns out that these or other things are sticking points and there does need to be some interactive sensor to keep everything copacetic, then it is back to George's ECU. With it, there's going to be the need to duplicate the functionality of the Toyota in-tank gauges/sensor assembly to feed it good data. If you use Toyota parts, it's plug and play, the main issue is gathering everything together.

There may be a way to do that with a variety of auxiliary tanks, but it may be easier in the end to pick a specific set of tanks to tailor the sensors, etc to, because things quickly get complicated with trying to engineer that part of the system to a wide variety of possible tanks.

I need to dig further at this point to understand the functionality of the ECU and how a manual system would work or not in trying to substitute for it. That's one part of this.

The other part is figuring out the tank or tanks that would work best to adapt to mounting in a range of choices, i.e. ~14 gallons like the OEM subtank, ~25 gallons as a happy medium for range and clearance, and the long-range option with ~40 gallon tank. I need to go back through the tanks I extracted previously and check out the ones that will fit more like the OEM subtank now that I understand it better. I like the idea of using brackets rather than straps, as it just seems the better method for an off-roadable vehicle.

 

[alia176]

Mike,

The "empty" signal from any OEM tanks usually comes on with few gallons left in the tank. I mean, that's our empty signal works, right? So, you won't have to worry about running the tank dry if you go the ECU route. However, if you do the manual route, I think you'll run it dry - simply because you'll be doing something like driving, wheeling, spotting, etc while the fuel is transferring.

My ECU is connected to the IGN power source so the pump doesn't run with key off. However, you can easily power it constant HOT I suppose. I didn't encounter any occasion where I wished the system ran with key off but there's always an exception to everything I guess.

IIRC, the fuel path is like this: subtank outlet to pump to main tank vent line. Usually, when the main tank is half full, I'd turn on the transfer process and let it do its thing. But, if I had a 25g sub tank, then I'd have to be real careful when to transfer the fuel. It wouldn't be too much effort to purchase a typical dual tank switching valve from NAPA that has two feed/two vent/return lines. With a little work with a relay, you could get a super trick system that draws/returns from the same tank AND the fuel gauge shows the status of the "current" tank. Perhaps a trip to the junk yard to see what the domestic trucks with dual fuel tanks are doing these days. Again, if you want to get super trick and complicate things. I may go this route if a 25g subtank jumps into the mix, who knows. I like complicated wiring.

As far straps, this is how the main tank is installed into our 80's and so far it's holding on fairly well I think. What ever you do, you'll need to make sure that the tank moves with the body IMHO.

 

[1FZj80]

WRONG!!!!

Toyota never offered sub tank for 80 series with pump in a tank.

Only 100 series series got sub tank with pump in the tank system.

You most likely got 100 series tank from them. I had few members contacting me with issue that SOR sold them wrong tanks or straps.

??? I never said my tank was from an 80. Read my posts. I said I have the 80 Series Aux Fuel Tank from SOR. SOR says this about the tank: "SOR has been able to source the OEM Toyota 50 Liter (13.2 US Gallon) capacity subtank for the 80 series vehicles". For all I know it came out of a Hilux and just happens to fit the 80.

Nor did I say that TOYOTA offered a sub tank for thew 80 with a pump in the tank???

Why are you giving me sh*t...

 

[greentruck]

Mike,

The "empty" signal from any OEM tanks usually comes on with few gallons left in the tank. I mean, that's our empty signal works, right? So, you won't have to worry about running the tank dry if you go the ECU route. However, if you do the manual route, I think you'll run it dry - simply because you'll be doing something like driving, wheeling, spotting, etc while the fuel is transferring.

OK I see how that works. What I wonder is if we get a pump different than the OEM, do they typically have this circuitry? Makes sense, because everything's fuel injected these days and you need that signal as part of the "make good" for it?

My ECU is connected to the IGN power source so the pump doesn't run with key off. However, you can easily power it constant HOT I suppose. I didn't encounter any occasion where I wished the system ran with key off but there's always an exception to everything I guess.

Yeah, I prefer key-on power. I spend a lot of time in the backcountry, have to run a CPAP machine all night and conserving battery power is important. I don't want to be pumping gas somehow when I need to be pumping air...

IIRC, the fuel path is like this: subtank outlet to pump to main tank vent line. Usually, when the main tank is half full, I'd turn on the transfer process and let it do its thing. But, if I had a 25g sub tank, then I'd have to be real careful when to transfer the fuel. It wouldn't be too much effort to purchase a typical dual tank solenoid valve from NAPA that has two feed/two vent/return lines. With a little work with a relay, you could get a super trick system that draws/returns from the same tank AND the fuel gauge shows the status of the "current" tank. Perhaps a trip to the junk yard to see what the domestic trucks with dual fuel tanks are doing these days. Again, if you want to get super trick and complicate things. I may go this route if a 25g subtank jumps into the mix, who knows. I like complicated wiring.

I don't like complicated wiring, so if I go the opposite direction you're inclined to, I should be safe, right?

I am beginning to size this up and you hit on something that was becoming more clear to me as I re-digested these subtank threads. Yep, it's kind of hard to just pump the 25 gallon (or bigger) subtank into a 25 gallon main tank. With the 13 gallon subtank, manual control might work without issues so long as a way can be figured to avoid running the pump dry. For the bigger ones, you kind of need the smarts of the ECU to avoid problems.

I see the OEM control system and George's adaption of it as having two basic functions to avoid problems. First, it senses whether the main tank is full. Second, it senses whether the subtank is empty. If either condition occurs, it shuts down the transfer. This works admirably to simply control a transfer.

I presume that there is no issue with the shutdwon signal and George's ECU (or GECU for short) for the main tank in any case. We've all got what's needed already installed in the tank from the factory. It's merely a matter of wiring it to the GECU.

The subtank is where it gets iffy. Can the aftermarket in-tank pumps or senders give us the signals that the GECU needs? if so, probably easiest and cheapest. If not, then there's Toyota senders. I saw one for the 13 g subtank adapted for a deeper subtank. I'd much prefer a bolt-in solution, just not sure about this yet.

As far straps, this is how the main tank is installed into our 80's and so far it's holding on fairly well I think. What ever you do, you'll need to make sure that the tank moves with the body IMHO.

Yeah, not too worried about straps, just noticed how they used brackets for the subtank. I think which works depends on how close the tank fits to the frame and/or x-members. Haven't had a chance yet to go back through the tanks.

In the end, I think breaking the control system part from the tank part in terms of thinking about things helps me. The part about getting aftermarket non-Toyota tanks to work may have some appeal to those who already have all the other goodies in place with the small subtank, but want to upgrade to something bigger. I'll work more on that in the next day or two.

As for the rest, I have a pretty good handle on what needs done now with the exception of getting the sender and signals from a non-OEM subtank to work.

I did find a pump # that Cruiserdrew came up with that would work from the transfer pump, NAPA Part # P74019 (Hecho in USA!) at about $50. Pic here:
https://forum.ih8mud.com/80-series-tech/150756-oem-sub-tank-aux-fuel-tank-setups-faq-3.html
Not sure about something to replace the OEM solenoid valve yet, but that and the switches, gauging, etc can probably be found in US-market aux tank supplies as you indicate.

Gotta hit the sack for now.

 

[alia176]

Mike,

One thing needs to be made clear: GECU does NOT monitor main tank "full" signal and therefore does NOT turn off the transfer pump. He kept it simple by not having to deal with tapping into the main tank level sensor circuit. Remember, there is not a "full" (digital) signal coming out of any of our main gas tanks so adapting to an analog sensor signal gets tricky and he avoided this all together.

No matter which tank you go with, as long as you order the level sensor with it, I think you'd be fine. Junk yard tanks will have their own fuel pumps and sending units and new tanks could be ordered in the same manner. I'm guessing that most aftermarket tank sending unit comes with a "empty" digital signal. However, one needs to make sure that this signal follows the same electrical properties as the oem subtank. By this, I mean we need to know if the oem subtank sending unit switches "ground" or "hot" during the "empty" state. I don't know which way GECU would like to see this signal. Again, a quick PM to George would clear this up.

I'm not sure what GECU's rating is in terms of power output. Is this unit set to handle a typical fuel injection in tank pump vs a typical transfer/carburetor pump? My guess is that it should be ok but this is something that needs to be verified with George. Once you find out the typical current draw of the in tank pump you're looking at, shoot him a PM just to verify.

Regardless of what type of pump one uses (in tank vs transfer), conceptually, GECU will handle the task with ease. It simply turns on/off a "pump", so it doesn't care where it is. His older GECU has a second output for a solenoid valve (SV), which was common in the OEM transfer system from OZ. My guess is that this was to prevent the siphoning between the tanks. However, since we're purchasing pumps with built in check valves, we should be ok not to use a separate SV. I'm not using the SV output on my GECU.

Let me know if any of this is unclear.

Ali

 

[greentruck]

Mike,

One thing needs to be made clear: GECU does NOT monitor main tank "full" signal and therefore does NOT turn off the transfer pump. He kept it simple by not having to deal with tapping into the main tank level sensor circuit. Remember, there is not a "full" (digital) signal coming out of any of our main gas tanks so adapting to an analog sensor signal gets tricky and he avoided this all together.

Ali,
OK, got that. So I suspect that the OEM ECU doesn't have a Full signal either and likewise relies solely on the Empty signal from the subtank to trigger power off to the transfer pump.

No matter which tank you go with, as long as you order the level sensor with it, I think you'd be fine. Junk yard tanks will have their own fuel pumps and sending units and new tanks could be ordered in the same manner. I'm guessing that most aftermarket tank sending unit comes with a "empty" digital signal. However, one needs to make sure that this signal follows the same electrical properties as the oem subtank. By this, I mean we need to know if the oem subtank sending unit switches "ground" or "hot" during the "empty" state. I don't know which way GECU would like to see this signal. Again, a quick PM to George would clear this up.

OK, I think I have a specific enough question to ask George after study of the EWD on this question. I know I saw the subtank EWD somewhere, either elmariachi or Romer's thread, if it's not in the EWD book, which I have. Once we know what the GECU needs as a signal, we'll be able to spec the fuel pump.

As you can tell, I'm a carbureted guy living in a fuel injected age...
But I am learning fast with your help. The bonus is that the others following along are learning, too, and should chime in if they're as confused as I was to begin with.

I'm not sure what GECU's rating is in terms of power output. Is this unit set to handle a typical fuel injection in tank pump vs a typical transfer/carburetor pump? My guess is that it should be ok but this is something that needs to be verified with George. Once you find out the typical current draw of the in tank pump you're looking at, shoot him a PM just to verify.

Yes, sounds like a plan on that, as it will help us with a generic spec so that someone wanting to do things a little different could compare the specs of any pump they might have in order to see it it'll work with the GECU.

Regardless of what type of pump one uses (in tank vs transfer), conceptually, GECU will handle the task with ease. It simply turns on/off a "pump", so it doesn't care where it is. His older GECU has a second output for a solenoid valve (SV), which was common in the OEM transfer system from OZ. My guess is that this was to prevent the siphoning between the tanks. However, since we're purchasing pumps with built in check valves, we should be ok not to use a separate SV. I'm not using the SV output on my GECU.

Let me know if any of this is unclear.

Ali

OK, that will simplify things if not needed. But I suspect it might be because of the fact that many want to put something larger than the 13 g subtank in. If you try to pump 20 gallons into a half-empty main tank, you will fill it to the point of potentially starting a siphon back to the subtank. This might not matter I suppose, because once enough is siphoned back through the vent line used to supply the main from the sub via a T or Y connector, it will lower the main level enough to break the siphon.

Now, if the transfer pump is off when the siphon breaks, that's the end of it. But with the pump left on and no Full signal from the main, then a cycle may start where the siphon keeps making and breaking. I supposed no big deal for the fuel pumps rated as primary pumps, but used in the case of the subtank as a transfer pump. But for those who use a cheaper transfer pump, it may not be rated for continuous duty? I don't know.

[EDIT: I suspect that a siphon could only occur with the pump off, because there's no way back to the subtank from the main other than the vent line that the pump is pushing the fuel from the sub to main and the filler, which may not work as a siphon? I may be missing something here and making a bigger deal out of the siphon than is warranted?]

However, this does illustrate a problem when the subtank is close to equal or larger than the main if there is no Empty signal from the main to shut things down. Or is it really a problem, if things just circulate back to the subtank via the filler, I guess?

In either case, for any tank larger than the 13 gallon, it makes me wonder is we shouldn't explore a built-in timer in the circuit, where the pump runs until either A) Empty signal from subtank or B) 15 minutes have passed. That way the system will time out.

This is starting to get much more clear and I very much appreciate your patience and assistance in understanding things so those working on this project have a good idea of what we either need to duplicate or provide an alternative solution to what's already available to work with.

 

[scottryana]

Sure this is easier than a bulletproof gravity system? All kidding aside.

I would still use a check valve in the line you are using to prevent any type of siphoning, but the other issue is if you pump the main tank over filled you will be pushing gas into the charcoal canister system.

On a side note, my tank design is almost done, I will be using 3/16" aluminum, with AN -10 fittings, steel braided teflon hose, and a AN -10 one way valve. The tank will be 6" deep at the deepest point and hold about 12 gallons, and will be completely above the frame rails. I will be using the L brackets from the stock spare tire carrier to mount the tank.

 

[locrwln1]

Like others have noted, the "tank" is the easy part, it's the dual filler neck that is the challenge.

On my '96 I had the MAF 24g aux tank and 4x4labs rear bumper. Too bad the price has gone up so much on their system. I loved mine, it worked great and fit my needs. I wouldn't waste time on a OEM 13g tank, as Alia has noted while it helps, it's not enough for a fuel sucking, armored 80. I learned after a central Nevada trip that even 49 gallons is barely enough.

MAF uses a simple switch/fuel gauge combo that is pretty sweet and compact. I used a single A-piller guage pod to mount mine in my line of sight. I never had problem with transfering the fuel. The first trip I did, I waited until the main tank was almost empty. I was driving home from Death Valley up 395 north up and over the Sierra's and the fuel transfer was happening at the same rate as the truck was using it, so the main tank guage didn't move. After that, I learned to transfer fuel as I was driving in less demanding situations. I would hit the switch until the main guage showed full, then switch it off. My thinking was that I was transferring that much weight forward as soon as possible, which helped with the handling offroad.

Jack

 

[scottryana]

Yeah I ordered a new dual filler neck from Akella, should ship out on the 25th.

For me having an extra 10-15 gallons should be ok, I know that there are some trips that would require higher fuel loads, but it is more important to me to have the tank up above the frame rails. I think it is a much better option than having 130# of fuel load mounted high on the back bumper on a long moment arm behind the rear axle. Everyone uses their 80's for different things, so I suppose that is why there is no "right" answer on how to do this.

Like others have noted, the "tank" is the easy part, it's the dual filler neck that is the challenge.

On my '96 I had the MAF 24g aux tank and 4x4labs rear bumper. Too bad the price has gone up so much on their system. I loved mine, it worked great and fit my needs. I wouldn't waste time on a OEM 13g tank, as Alia has noted while it helps, it's not enough for a fuel sucking, armored 80. I learned after a central Nevada trip that even 49 gallons is barely enough.

MAF uses a simple switch/fuel gauge combo that is pretty sweet and compact. I used a single A-piller guage pod to mount mine in my line of sight. I never had problem with transfering the fuel. The first trip I did, I waited until the main tank was almost empty. I was driving home from Death Valley up 395 north up and over the Sierra's and the fuel transfer was happening at the same rate as the truck was using it, so the main tank guage didn't move. After that, I learned to transfer fuel as I was driving in less demanding situations. I would hit the switch until the main guage showed full, then switch it off. My thinking was that I was transferring that much weight forward as soon as possible, which helped with the handling offroad.

Jack

 

[locrwln1]

I wheeled all over the Sierra's, DV, Deer Valley trail (similar to Rubicon), Moab, NV, you name, that truck went every where. I never once hit or came close to the rear aux tank. It would take a very specific rockcrawling type incident to hit the tank. But like you said, no wrong answers. I had a 4" Slee lift with 35's.

Here is a pic of the rear tank/side view, it's the light grey triangle looking thing behind the exhaust:


Here is a pic from the driver's side:


Here is the guage/switch:


Jack

 

[scottryana]

Well mine has to be high because I am gravity feeding to the main tank, I am not all that worried about hitting it all though I did have 2 fairly good rear drags this weekend, from rolling off of tall ledges.

I wheeled all over the Sierra's, DV, Deer Valley trail (similar to Rubicon), Moab, NV, you name, that truck went every where. I never once hit or came close to the rear aux tank. It would take a very specific rockcrawling type incident to hit the tank. But like you said, no wrong answers.

Jack

 

[alia176]

Thanks for chiming in Jack, it's helpful to see a side profile shot of your 25g tank. Agreed, if the MAF tank wasn't so astronomical in price, I'd consider it as it's a nice package. Just so everyone knows, jack is about .50 when it comes to wiring and he did a nice job of installing this tank system. Using GECU with MAF gauge would be super trick IMO. I can already smell the solder burning......

 

[locrwln1]

Well mine has to be high because I am gravity feeding to the main tank, I am not all that worried about hitting it all though I did have 2 fairly good rear drags this weekend, from rolling off of tall ledges.

Not sure how you are going to get the aux tank high enough to fully feed the main tank. Are you going to drill a port into the main tank? I don't think gravity is going to work all that well. JMHO of being under and around every part of the main and aux tank system. YMMV.

Thanks for chiming in Jack, it's helpful to see a side profile shot of your 25g tank. Agreed, if the MAF tank wasn't so astronomical in price, I'd consider it as it's a nice package. Just so everyone knows, jack is about .50 when it comes to wiring and he did a nice job of installing this tank system. Using GECU with MAF gauge would be super trick IMO. I can already smell the solder burning......

I think you are being generous as far as my wiring abilities...

The only thing that would concern me with GECU would be when the aux gauge read empty, there was at least 5 gallons left in the aux tank. I suppose you could "tune" the sending unit, but I know I ran mine until the main guage stopped rising and never had a problem with the pump. In fact, I "forgot" about the switch being on several times and it ran for I don't know how long before I remembered to turn it off.

Jack

 

[scottryana]

Yes will drain and drop the tank, have it flushed at a radiator shop, drill a port in the main tank and weld on an AN -10 fitting. The gauge will read normal until around 1/2, full and then will stay 1/2 full until the aux tank is empty and then will drop to empty like normal. Or at least that is the plan.

Not sure how you are going to get the aux tank high enough to fully feed the main tank. Are you going to drill a port into the main tank? I don't think gravity is going to work all that well. JMHO of being under and around every part of the main and aux tank system. YMMV.



I think you are being generous as far as my wiring abilities...

The only thing that would concern me with GECU would be when the aux gauge read empty, there was at least 5 gallons left in the aux tank. I suppose you could "tune" the sending unit, but I know I ran mine until the main guage stopped rising and never had a problem with the pump. In fact, I "forgot" about the switch being on several times and it ran for I don't know how long before I remembered to turn it off.

Jack

 

[greentruck]

Scott,
Yes, I think we all have different goals and needs, but this thread is starting to help us understand the basics of the system design so we can adapt to what we each seek. Your comment on the limitations of gravity feed is one of them. There's only so much space that's higher than the main tank, so it sounds like the ~13 gallons may be close to the practical limit once you get the plumbing worked out?

That's a good thing to know for the guy planning the 40 gallon gravity feed tank...

Jack,
Do you recall, the MAF gauge/switch... which one is it on this page?:
http://www.man-a-fre.com/parts_accessories/FuelSelectorSwitchValveLongRangeFuelTanks.htm
They omitted any illustration, but I'm guessing the one with the fuel gauge is the more expensive one. Or is it another item entirely? Looks like it works with the GECU, although I'm sure there are other alternatives out there.

Ali,
I agree, Yes, Jack's pics show how the 25 gallon doesn't really hang down that much. Sure, something to be aware of and perhaps armor. But my spare is way lower than that right now, so taking it out and putting the tank in significantly improves the departure angle for me. The big tank on my FJ55 hung down considerably more than Jack's, although I don't think it was as low as my spare is right now.

 

[Wheelingnoob]

Do you recall, the MAF gauge/switch... which one is it on this page?:
http://www.man-a-fre.com/parts_accessories/FuelSelectorSwitchValveLongRangeFuelTanks.htm
They omitted any illustration, but I'm guessing the one with the fuel gauge is the more expensive one. Or is it another item entirely? Looks like it works with the GECU, although I'm sure there are other alternatives out there.

Interested to see if that is the same one as the 24 gallon kit. If it is it takes two of the main things off my list. I'm looking very closely at a few of the tanks posted earlier. I just got my custom rear bumper done and have the trailer hitch cross member set-up to be one of the tank mounts. In hind site I should have got the tank first and made the bumper around it.

 

[scottryana]

Yes with the space available, about 40"x20" minus room for brackets and the required depth that you need to stay above the main tank, above the frame rails and create slope for gravity feed you are limited to about 12 gallons. Like I said you could cut corners and do it wrong using a drain hole or some other tank that wasn't designed for this, but this will be a dedicated gravity feed tank with the port on the bottom face of the front of the tank

Scott,
Yes, I think we all have different goals and needs, but this thread is starting to help us understand the basics of the system design so we can adapt to what we each seek. Your comment on the limitations of gravity feed is one of them. There's only so much space that's higher than the main tank, so it sounds like the ~13 gallons may be close to the practical limit once you get the plumbing worked out?

That's a good thing to know for the guy planning the 40 gallon gravity feed tank...

 

[hoser]

I know we've been calling the 24 gallon tank a MAF tank but it was actually manufactured by Long Range Automotive. Outback Proven is a new US dealer for them and might offer good price.

I've generally been happy with mine for my 100.

 

[hoser]

Interested to see if that is the same one as the 24 gallon kit. If it is it takes two of the main things off my list. I'm looking very closely at a few of the tanks posted earlier. I just got my custom rear bumper done and have the trailer hitch cross member set-up to be one of the tank mounts. In hind site I should have got the tank first and made the bumper around it.

I do like the switch. It has an auto dimmer too, so gets dimmer in darker light. The "E" will flash when it is near empty. However, it will not automatically shut the transfer off. The manufacturer of the switch is apexes, Model PG200-b.

www.apexes.com.au