Aux fuel tank dual fill neck

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Octanejunkie

Octanejunkie

Joined
Mar 4, 2022
Threads
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Location
Los Angeles, CA
Looking to add an aux tank to my 80. LRA is $$$. Found this thread: Aux fuel tank - https://forum.ih8mud.com/threads/aux-fuel-tank.1354848/

Anyone use a factory 100 series dual fill next like this for an 80? LRA provides something similar with their kit but won't sell it separately.
Toyota PN 77201-60600
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Might pair well with an S10 tank per linked thread
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33 x 22 x 10.5
 
Octanejunkie said:
Looking to add an aux tank to my 80. LRA is $$$. Found this thread: Aux fuel tank - https://forum.ih8mud.com/threads/aux-fuel-tank.1354848/

Anyone use a factory 100 series dual fill next like this for an 80? LRA provides something similar with their kit but won't sell it separately.
Toyota PN 77201-60600
View attachment 4081102
Might pair well with an S10 tank per linked thread
View attachment 4081106
33 x 22 x 10.5
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I've got the 24 gal LRA tank with the dual filler neck they supplied. Although they"re expensive, they're rugged and mine has held up well for the 8+ yrs it's been installed. The pic in your post of the 100 series filler neck looks like it'll be "fun" to install. You'll be loosening and removing body mounts to get it to fit - if it fits at all.

BTW, one of the steps in the LRA install is to cut the original single filler neck in two, so you can remove it and not have to pry the body and frame apart. Just so you know what you're getting into, regardless of what aux tank and filler neck you choose. Good luck. Having an aux tank is so much better than messing with jerry cans!
 
I added the S10 aux tank about three years ago before tariffs. Works great and used the 100 series neck. There is another older MUD thread with more details. A few photos below. One shows OEM filler piece I cut out. Another of skid plate I added. I was inspired from a friend that did the same mod.

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Wayneraintree

For Sale Thread '79 Series Sub tank Northern Kentucky'

79 Series Land Cruiser sub tank complete factory take-off purchased from cruiserparts. Tank, straps, and skidplate as pictured. I ended up using a different tank for my 45 so this is available. I've seen them used in 80 series where the spare tire goes or would be an awesome OEM piece on any pickup or ute. 250$ or trade for parts of equal value. Happy to mudship or meet within reasonable distances.

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Octanejunkie said:
So many moving parts tho
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Not really many moving parts, it's just a diverter flap and a knob to operate the flap direction.

I've had the factory tank, fuel transfer pump/solenoid and the dual neck filler installed in my 80 for 25+ years. It has been rock solid reliable. I'm probably one of the 1st folk in the US to install the setup way back then. I was down in socal and was picking up a rack from manafre and figured to drop into to SOR. Chatted with Marv and he mentioned he had the tank stuff sitting waiting to install in his 80 - but gentleman that he was (and salesman) offered to sell it to me if I was interested. Heck yeah. Was about $800 for the lot. Maybe he liked my authentic aussie accent :rofl:

My write up on the install from way back when -> Auxiliary tank - https://george4wd.taskled.com/auxtank.html

And yes, I cut the original pipe way back when to extract it and that was my own 'invention' at that time.

cheers,
george.
 
george_tlc said:
Not really many moving parts, it's just a diverter flap and a knob to operate the flap direction.

I've had the factory tank, fuel transfer pump/solenoid and the dual neck filler installed in my 80 for 25+ years. It has been rock solid reliable. I'm probably one of the 1st folk in the US to install the setup way back then. I was down in socal and was picking up a rack from manafre and figured to drop into to SOR. Chatted with Marv and he mentioned he had the tank stuff sitting waiting to install in his 80 - but gentleman that he was (and salesman) offered to sell it to me if I was interested. Heck yeah. Was about $800 for the lot. Maybe he liked my authentic aussie accent :rofl:

My write up on the install from way back when -> Auxiliary tank - https://george4wd.taskled.com/auxtank.html

And yes, I cut the original pipe way back when to extract it and that was my own 'invention' at that time.

cheers,
george.
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I agree. Not many moving parts, just a flapper and a simple linkage system to operate that flapper.

I bought my dual filler neck and 42 aux gallon tank from Man-a-Fre long time ago. The fact I bought a LRA aux tank from Man-a-Fre tells how long ago it must have been. 😉

Looking at yours, mine has different overflow lines that didn't fit with the larger tank lines from the bottom section. I think our bottom section is the same. The overflow lines had to be shortened to make work. From memory, Man-a-Fre said it was the only dual filler that they could get at the time.

I recently picked up 77201-60312, which is still available, and not that expensive. However, I couldn't make it with with the lower section that I have.

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NorthWA said:
I added the S10 aux tank about three years ago before tariffs. Works great and used the 100 series neck. There is another older MUD thread with more details. A few photos below. One shows OEM filler piece I cut out. Another of skid plate I added. I was inspired from a friend that did the same mod.

View attachment 4081370View attachment 4081373View attachment 4081374View attachment 4081375View attachment 4081377
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This looks like the direction I am leaning, however I would prefer less of the tank hanging below the frame rails. A 13.2 gallon tank from a 1985 S15 Jimmy has the same shape and dimensions but is 8.75" deep vs the 19/20 gallon at 10.5/11" and also came fuel injected with an in tank pump
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$200 for the pair off Amazon, eBay, etc.

I'm okay with cutting the fuel fill neck to remove as well as cutting the new one to install
 
I have had the LRA 24 gal for several years now and there filler neck is a very simple design with no moving parts and was relatively easy to install. Not sure if they sell filler neck separately though. Might be worth looking into.
 
Octanejunkie said:
This looks like the direction I am leaning, however I would prefer less of the tank hanging below the frame rails. A 13.2 gallon tank from a 1985 S15 Jimmy has the same shape and dimensions but is 8.75" deep vs the 19/20 gallon at 10.5/11" and also came fuel injected with an in tank pump
View attachment 4081802
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$200 for the pair off Amazon, eBay, etc.

I'm okay with cutting the fuel fill neck to remove as well as cutting the new one to install
Click to expand...
From the pic of the tank, that should work well to clear the stock exhaust on the 80. What are you going to use for a switch and gauge? I might caution you to use a sturdy switch, and at least 16 AWG wire. It’s tempting to use smaller wire, but my experience has been that it could cause problems with the speed and reliability of the pump. I had to modify my set up with the 24 gallon LRA tank to get it to work reliably.
 
80t0ylc said:
From the pic of the tank, that should work well to clear the stock exhaust on the 80. What are you going to use for a switch and gauge? I might caution you to use a sturdy switch, and at least 16 AWG wire. It’s tempting to use smaller wire, but my experience has been that it could cause problems with the speed and reliability of the pump. I had to modify my set up with the 24 gallon LRA tank to get it to work reliably.
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I'll be hard installing a compressor in the rear so I'm running a fused 4AWG feed to the rear that I'll tap off for the pump. I'm planning on using a momentary switch and a neutral-switched timer relay and 30A fused circuit for the pump.
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HELLA 996152131 12V Delay-On-Release, Time Delay Relay​

 
Octanejunkie said:
Just a thought, with ordering from abroad being a no go right now would it be feasible to just intercept the factory fill and vent tubes near the bend upwards and allow the overfill to direct itself to the aux tank?
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If you're referring to the 100 series dual fill, it looks from the pic in 1st post like you won't have to worry. It looks to be designed similar to the dual feed neck that's supplied with the LRA kit (mine anyway - I don't think they've changed). They're designed so there is no way that you can over fill the OEM tank pumping fuel from aux to main. If you forget and leave the pump on, the fuel will just dribble back into the aux tank through the dual neck. I still like the LRA better - it allows you to choose which tank to fill. That's the way it should be, IMHO.
 
White Stripe said:
My concern would be if the shaft seal for the flapper leaks. Then you have a evap system leak.
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IME with my LRA 24 gal aux, it wouldn't matter. There is no direct vent line from the aux tank to the charcoal canister. So vapor pressure from the aux tank vent line is also transferred to the main tank which makes it double of what it's designed to handle, being that the aux and main tank are roughly the same size. I've done the LCP mod on the canister to no avail and pressure just builds up that the system can't handle. So my redneck fix is to not tighten the fuel cap so my tanks don't fracture from the pressure. Where I live is very rural, so there is no smog inspection. The fuel vapor just escapes which probably negatively affects my mpg, but the advantages of the aux tank make it a tradeoff that I can live with. My LRA tank doesn't have a fitting to connect to a charcoal canister. Not sure if the newer LRA tanks allow the canister connection.

@greentruck - Mike, do you know how your evap system with your aux and main tanks are set up? Do you get the "woosh" when you open your fuel cap? It's worse in summer heat so you may not have noticed it lately.
 
80t0ylc said:
If you're referring to the 100 series dual fill, it looks from the pic in 1st post like you won't have to worry. It looks to be designed similar to the dual feed neck that's supplied with the LRA kit (mine anyway - I don't think they've changed). They're designed so there is no way that you can over fill the OEM tank pumping fuel from aux to main. If you forget and leave the pump on, the fuel will just dribble back into the aux tank through the dual neck. I still like the LRA better - it allows you to choose which tank to fill. That's the way it should be, IMHO.
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I'm saying If I can't get the 100 series dual fill neck why not just T off the stock fill neck and vent?

Found this article, similar thought:
Simple Dual Fuel Tank Plumbing - Will this work? | Expedition Portal Simple Dual Fuel Tank Plumbing - Will this work? - https://share.google/exfFWe8TT3NHw7xG9

Something like this
17734065075006864612445269836495.webp

Do the same thing with the fill vent
 
80t0ylc said:
IME with my LRA 24 gal aux, it wouldn't matter. There is no direct vent line from the aux tank to the charcoal canister. So vapor pressure from the aux tank vent line is also transferred to the main tank which makes it double of what it's designed to handle, being that the aux and main tank are roughly the same size. I've done the LCP mod on the canister to no avail and pressure just builds up that the system can't handle. So my redneck fix is to not tighten the fuel cap so my tanks don't fracture from the pressure. Where I live is very rural, so there is no smog inspection. The fuel vapor just escapes which probably negatively affects my mpg, but the advantages of the aux tank make it a tradeoff that I can live with. My LRA tank doesn't have a fitting to connect to a charcoal canister. Not sure if the newer LRA tanks allow the canister connection.

@greentruck - Mike, do you know how your evap system with your aux and main tanks are set up? Do you get the "woosh" when you open your fuel cap? It's worse in summer heat so you may not have noticed it lately.
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The lra tank runs close to the exhaust. If you haven't yet you might need to look into heat management. The main tank has little heat protection too.
 
80t0ylc said:
IME with my LRA 24 gal aux, it wouldn't matter. There is no direct vent line from the aux tank to the charcoal canister. So vapor pressure from the aux tank vent line is also transferred to the main tank which makes it double of what it's designed to handle, being that the aux and main tank are roughly the same size. I've done the LCP mod on the canister to no avail and pressure just builds up that the system can't handle. So my redneck fix is to not tighten the fuel cap so my tanks don't fracture from the pressure. Where I live is very rural, so there is no smog inspection. The fuel vapor just escapes which probably negatively affects my mpg, but the advantages of the aux tank make it a tradeoff that I can live with. My LRA tank doesn't have a fitting to connect to a charcoal canister. Not sure if the newer LRA tanks allow the canister connection.

@greentruck - Mike, do you know how your evap system with your aux and main tanks are set up? Do you get the "woosh" when you open your fuel cap? It's worse in summer heat so you may not have noticed it lately.
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Same as factory. Whoosh is the same as before the auxiliary tank went in, Before that, with the larger LRA main in, the whoosh seemed a bit more intense at times. Summer heat and increased altitude seem to increase it, but even this varies.

It's worth noting that that the two tanks are connected at the fill neck,
 
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