[Jezza86]

Does anybody have a photo, or are they able to describe the fuel tank breather on the (05+? have they changed ever?) jimny fuel tank.
id like to strap down a 45L boat fuel tank inside the car to act as a extended fuel tank when needed.
my intent is to use similar to a boat fuel line with the bayonet fuel fittings and let gravity and vacume do the work for me.
or likewise is there a easier way to get fuel from the tank to the engine?
im aware ill have to make a way for the internal tank to vent to outside the car so i don't get too high...

cheers

Jeremy

[Jezza86]

after doing some more research i think i've found the answer...


the air is sucked in to the tank via the fuel cap apparently, but positive pressure is relieved via the charcoal canister into the intake manifold.
so in short, i think this will work...

[Gwagensteve]

Jezza86 wrote:

Does anybody have a photo, or are they able to describe the fuel tank breather on the (05+? have they changed ever?) jimny fuel tank.
id like to strap down a 45L boat fuel tank inside the car to act as a extended fuel tank when needed.
my intent is to use similar to a boat fuel line with the bayonet fuel fittings and let gravity and vacume do the work for me.
or likewise is there a easier way to get fuel from the tank to the engine?
im aware ill have to make a way for the internal tank to vent to outside the car so i don't get too high...

cheers

Jeremy

I'll play.

If I understand what you're planning properly, I think this is a really dumb idea. I'm just thinking out loud here, so if you've thought all this through that's cool, but I'mn ot sure about this at all.

I assume you are using something like this.



https://www.whitworths.com.au/main_item ... olutePage=

The fuel system in a modern, EFI car is sealed when the car is in operation. If the car is parked and turned off, there can be a reasonable amount of pressure in the fuel tank.
You're planning to install a boat tank, have a vented cap, and gravity feed it into the stock tank.

What is stopping the pressure built up due to the thermal expansion of 90L of fuel pushing liquid fuel out of your breather?

What happens when the fuel level is higher than the vapour line to the charcoal canister in the fuel tank and fuel starts being drawn up the breather into the canister?

All of the tanks I found on a quick search have their lines coming out of the top of them. How are you going to go gravity feeding that? You can't use suction, because the stock fuel cap eliminates that. I suppose you could "seal" the tank and have all the vacuum come from the in cab tank, but it has a vented cap, so you've now got double the thermal expansion of a 45L tank trying to push fuel out of a vented cap.

I'm just kicking ideas around, but really, getting this stuff to work is going to be pretty complex and require some trial and error, I think, and the concequences of an error are likely to be liquid fuel and/or vapour in your cabin, along with electrical stuff, your clothes, you etc.

All I can see with this plan is a smelly, dangerous, and complex solution to this:



Which will achieve the same thing but won't result in you creating a potential bomb.

Lots of boats are lost to fire each year.

Lots of outback travellers loose their cars to fire each year.

Play it safe. Keep fuel lines. vents, caps, fittings etc out of your interior.

Just my opinion.

[Jezza86]

thanks for your response and thoughts Steve. that's virtually the same as the tank i have.
my thoughts were that the tank would only be able to replace the volume of fuel used by the engine, as it would be getting sucked down the breather hose under vacuum at first. my plan was to fit one of theseto an extended breather tube and connect to the boat tank. then connect the breather on the boat tank up to where the breather was originality connected near the fuel cap. the only event where i can see this being flawed is if the car was left parked in the heat as per your example, fuel vapor could flow up through the breather and bubble into the boat fuel tank before finally being purged via a loose fuel cap. however from my understanding of the fuel cap design the cap only allows air to enter the tank to relieve a vacuum, not relieve pressure so if the fuel cap is tightened corectly this bubbling effect would be unlikely as the fuel within the vehicle would heat up faster, forcing fuel into the cooler main fuel tank, which remains pressurized until the car starts. however in the fuel tank there's a fuel cut valve that apparently stops liquid fuel flowing up the lines to the carbon can

with the engine on a valve opens drawing air through the carbon can from the fuel tank (and by the looks of the diagrams from underneath the canister, but i just had a feel under mine and i cant feel a open inlet as depicted). intake manifold vacuum wont pull fuel through the fuel cut valve from the fuel tank normaly, otherwise if you had a full tank of fuel you would flood your carbon canister and this would deliver raw fuel into the intake manifold.
however what im doing isnt normal, so i will test this by filling the car to the brim in a attempt to activate the fuel cut valve, and apply a vacuum to the carbon can intake tube, to see if i can draw up liquid fuel.


i think that the carbon canister would be under -ive pressure longer than usual due to the operation of the fuel cut valve causing it to fully purge fuel vapors collected by the carbon
i don't plan for this to be a everyday use system, just a temperory one for long trips, where the boat tank will ideally be sucked into the main tank before stopping anywhere.

[Gwagensteve]

Firstly, I do not believe the boat tank has a one-way vacuum cap. I believe it has a vented cap because marine motors don't have vapour recovery like emission controlled car, an therefore htey have to have a vented cap or the tank will pump up and/or flood the engine. I'm prepared to be proved wrong, but I reckon I'm right.

I understand the idea of what you are trying to achieve. I just can't understand for the life of me why you think it's better to put a (single) tank with lines, couplers, hose clamps, and a vented cap into the cabin of your car.

I've been involved in doing it, by relocating a stock fuel tank inside a hardtop vehicle. It was the owners choice, not mine, and its in a pretty radical car. It's no outback tourer.

How is what you are planning better than putting two completely sealed jerry cans inside your car? (because I really don't think it's better at all, I think it is much, much less safe.

Steve.

PS. Am I the only person that thinks this is a highly sketchy idea?

[atari4x4]

i agree, it's a shit idea & could potentially be quite dangerous.

K.I.S.S.

[Gwagensteve]

Or buy a jeep if you like to live dangerously.

Steve

[steve]

I would think it'd be illegal to have a permanent fuel tank inside the cab? I think there'd have to be some kind of safety standard because when you get squashed by a truck, instead of just some broken legs, you might be bbqd?

[Gwagensteve]

Oh, I'm quite sure it's illegal, but in this case I would have thought safety would have come into it before legalities.

Steve

[Ace]

Carry a freakin jerry can or two, save yourself a fire...

[Jezza86]

yep i know the breather on the boat fuel tank is just a hole with a screw plunging it when its not in use.
i wanted to connect the breather on the boat tank up to where the breather was originality connected near the fuel cap (of the car i meant). that way the air coming into the car fuel cap would enter the boat tank, and once the boat tank was empty, the air would go via the boat tank into the main tank.

I know that having a fuel and breather line entering the cab connected to a temperory fuel tank isnt going to be safer than 2 gerry cans.

i have used my gerri cans before. their plastic gerries, the screw on lid type. they blow up when shaken and look a bit dodgey, and their not overfilled.
then when i use them, bits are always wet afterward and that brings fumes into the car. they havent had fuel in them for months but i can still smell it on them.
i never considered a dedicated bolted down carrier like pictured, but mainly because i only intend on driving shorter distances with the boot full of camping gear.

when i have had to use the gerries i had to lay them on their side and strap them down, and that strapping restricts the expansion so the gerry buldges oddly. if i dont strap them this tight they move round too much. the idea of driving 200k of couragated dirt road before i could use the first gerry, then 400k before i can empty the second is what made me think of using the boat tank in this way, because its designed to sit flat i dint have to worry about it falling over, and it already has designated strap locations where i could secure it in the back of my car.
problem is you cant exactly pour a 45l boat tank into your fuel filler cap on your car, so i was trying to come up with another strategy to get the fuel into the car.

you might think i should have started with a question rather then a idea like i did, but i like to ty to think outside the box, and i allready know what everyone elses ansewer would be. carry a gerry can or 3.

[Jimny1]

Jezza86 wrote:

and i allready know what everyone elses ansewer would be. carry a gerry can or 3.

Surley thats got to tell you that a faint whiff of petrol is better than being a crisp Kebab.

[royce]

If you have the tank already and are dead set on using it, if you squeeze the primer bulb like a champion will that get enough flow through the hose to siphon the tank empty?

If so, when empty, pull over, take cap off, plug hose into boat tank and stick end into jimny filler, squeeze bulb like crazy and empty boat tank into jimny

after a tank of fuel you probably need to stretch your legs anyway and you arent trying to rely on some complex thing thats relying on vacuum, and what ifs on a sealed emmision control system

[Gwagensteve]

Jezza86 wrote:

when i have had to use the gerries i had to lay them on their side and strap them down, and that strapping restricts the expansion so the gerry buldges oddly. if i dont strap them this tight they move round too much.

There's your problem. Those plastic Jerry cans are horrible. I know they are approved, but I hate them and won't use them in my car.

Get real ex-German army cans. There's a reason they are called "Jerry" cans. They are a design masterpiece and in my opinion the safest way of carrying fuel.

I have two and they never leak, they never pump up, and they are clean as a whistle inside. . I have seen some dated 1942, and they still looked entirely fit for service.

The Chinese copies are rubbish. Stay away.

I use a 5L plastic can for my gardening two stroke, but it doesn't go in the car.

[Jezza86]

cheers and thanks guys.