Aux Fuel Mod

[TLynn]

I installed a 4 gallon race tank with foam on my 2019S following instructions from an article I found. Initial test failed and it was venting fuel onto the ground when I would open the main cap.

I joined the I3 FB group and someone recommended reversing the hoses so the fuel is being pumped up to the filler neck instead of down to the tank. That did the trick.

With my recent HS of Charge
code I am looking forward to the added range on my next trip. Around town I will keep the aux tank empty.

I quickly cancelled FB as the responses got away from the technical question I had. Obviously there is some added risk. No need to engage in an ongoing lecture.

 

[Mr. Mindless]

Source for the article? I just brought home a 2015 today and I’m already regretting the limited range after running around a bit, because I immediately fell in love with the car… I want to take it everywhere.

I was thinking about how to tie into a pressurized fuel system and it seemed reasonably possible, if details were around, but I was worried the unexpected fuel quantity changes would have the computer in fits.

 

[Mr. Mindless]

https://www.theautopian.com/why-bmw...-dangerous-gas-tanks-into-their-front-trunks/

 

[TLynn]

Mr M. That is the same article that I referenced. After looking at the attached photo you will see why the aux pump needs to be plumbed to the filler neck and not the lower side as it connects to the grey connector that goes to the Evap canister. I realize now that I directly filled mine with fuel which may eventually lead to a Ck Eng / canister replacement. In fact I can still smell fuel after a week.

If you do the mod it is also important to stop the flow of fuel before the indicator maxes out as there is considerable lag and will overfill into the canister.

Edit: Another thought/question; look at the size of the evap canister for such a small tank. Could we remove it and replace with a custom aux tank or weld expand the stock tank into that space? In CA we need to smog every 7 years or upon sale. Would need to trick or add a small Evap can somewhere else.

 

[Mustrum Ridcully]

The famous Rich Rebuilds along with junk resurrection Sam Crack are doing this race tank in the frunk in this video but that sure does not look like a salvage $3,500 i3 to me.

 

[Mustrum Ridcully]

Was that copper paint on it a BMW option? I have not seen one that color in the 150 or so that seem to be for sale at an given time looks like a Tera World version but they have not stated the year or I have missed it.

 

[robthebold]

Was that copper paint on it a BMW option? I have not seen one that color in the 150 or so that seem to be for sale at an given time looks like a Tera World version but they have not stated the year or I have missed it.

I think that's the color they call Solar Orange.

 

[TLynn]

Great video to demonstrate what we are attempting to accomplish. I plan to do my first road trip soon with the aux tank. Mr Crack mentioned in the vid adding 2 gallons at a time. I will take heed from someone else that did this mod and not overfill and avoid pushing fuel into the Evap canister (Again). I blew shop air into the vent for a while yesterday to air it out. I’ll probably just turn on the aux pump 30 seconds at a time as needed not going anywhere near the full mark.

 

[ksnax]

Edit: Another thought/question; look at the size of the evap canister for such a small tank. Could we remove it and replace with a custom aux tank or weld expand the stock tank into that space? In CA we need to smog every 7 years or upon sale. Would need to trick or add a small Evap can somewhere else.

I'm trying to figure other ways to 'Smokey Yunick' the fuel system and that is an interesting idea I had not considered. Sadly, I doubt much more than half a gallon or so could be added by relocating that however.

 

[alohart]

I think that's the color they call Solar Orange.

Correct! It was an option only on early i3's.

 

[Mr. Mindless]

Edit: Another thought/question; look at the size of the evap canister for such a small tank. Could we remove it and replace with a custom aux tank or weld expand the stock tank into that space? In CA we need to smog every 7 years or upon sale. Would need to trick or add a small Evap can somewhere else.

I was planning to look at how the evap ties in, and whether some lines could be rerouted to make a highest-point loop that's as high as possible under the cowl to reduce opportunity for liquid to enter.

I used to have a large transfer tank on a pickup that was tied into the filler neck. No evap issues on a diesel; all the venting was done through the transfer tank, and the fuel gauge just stayed full until the first hundred gallons was gone, and then measured the truck's 36 gallon tank after that.

If a frunk aux tank was bottom-fed into the stock gas tank filler neck, and the top of the evap loop was well above the top of the fuel level of all tanks, the aux tank could be the single fuel point, and once the gauge starts moving you know you're in the last 2 gallons of gasoline capacity. simple! If the feed line was at least 1/4" or so, the aux tank could be a single point of fill, too. Running an aux tank on small Honda generators is a related principle (but no evap/sealed system concerns to deal with)

(I haven't watched Rich's video yet, I expect much of this is covered if he did it well, which he typically does)

 

[TLynn]

I saw someone else move the Evap canister in the frunk on top of the aux tank.

 

[Ollie]

"Race" tanks are not to be used as fuel cells (even with foam). They are not DOT (USA) approved and can not be used to even transport fuel legally on the roadways. This also applies any fuel cans that you see people use to transport fuel for ATV's, dirtbike, jetski's and the like that are not DOT approved. It's exactly the same as if you where transporting fuel in a mason jar.

I know it's weird. You can use an original replacement tank that may be made of steel (cars from the 1900's) and your fine. But add or replace it with a tank that is used in almost all forms of motorsports and your pulling a Judas Priest. (that's a Breaking the Law reference for you young'ens).

 

[Mr. Mindless]

Seems an unquestionably safe assumption that anyone considering this is using an OE, DOT certified tank from... something, whose dimensions are just perfect for the available space.

 

[Ollie]

And now I'm reminded of another song. This one from Supertramp, "Dreamer". Not a single search of RJS fuel cells turn up a DOT approval. The fuel cell used in the Rich rebuilds/Sam Crack referenced video. Jaz fuel cells specially state they are "not" DOT approved. I'm a drag racer. I have a bit of a background. It costs money and testing to get DOT approval on a product. Just be careful out there.

 

[crp]

Was that copper paint on it a BMW option? I have not seen one that color in the 150 or so that seem to be for sale at an given time looks like a Tera World version but they have not stated the year or I have missed it.

Yes, my 2015 Rex is solar orange. It goes well (in my opinion) with the dark brown leather terra interior. I don't know exactly what years that it was available, but I don't think it was available on later models.

 

[ksnax]

And now I'm reminded of another song. This one from Supertramp, "Dreamer". Not a single search of RJS fuel cells turn up a DOT approval. The fuel cell used in the Rich rebuilds/Sam Crack referenced video. Jaz fuel cells specially state they are "not" DOT approved. I'm a drag racer. I have a bit of a background. It costs money and testing to get DOT approval on a product. Just be careful out there.

I don't think that is going to be something available on any accessory tank. I am guessing any approval would have to relate to specific installations, and the multitude of mount possibilities makes that impossible to apply on a broad level. An OEM tank in a non-OEM location likely automatically loses that certification.

 

[Mr. Mindless]

Good practical view of tank connections and evap connections in this video

 

[TLynn]

Just completed my first long trip with new wider S100 tires and aux tank. The tires made the ride much more comfortable and the extra fuel eliminated the need to be constantly hunting for charging stations (that work). I’m really enjoying this car now.

Only other improvement I am contemplating is reworking the front seats to a better foam and leather.