Aux tank installation 2018 GSA

Greg Rice

Premier Member
IBR Finisher
#3
Here is what I and many other BMW riders are doing to tap into the main gas tank.

This is pretty easy to do but please read everything and maybe ask others. I am doing this and it works great.

I can tell you what many BMW riders are doing today. We are no longer drilling a hole in the tank. I am doing this and I know of at least 20 others who are doing the same.

We are tapping into the main tank through the vent tube in the gas cap. The main tank then pulls the gas from the AUX tank through this vent line.

We remove the vent tube that runs to the charcoal canister and just move it out of the way incase you want to revert back to stock and remove the AUX tank.

The AUX tank is now the vent for the main tank.

Many of us are using the idea from a guy on advrider who makes tanks under the name camel-adv.com and it has worked perfectly for me and many others. It is much easier than drilling and 100% reversible. The only important thing to remember is to NEVER close your aux tank fuel petcock. Explanation to follow. When the main tank drains fuel, it sucks in air to replace the space - instead of using your vent to suck in air, I use it to suck fuel from an aux tank and the aux tank has a vent placed higher than the fuel level, usually near the top of the filler neck. All you need to do is take off your right side tank plastics, find the red filler neck and on the right side remove the vent hose going to the charcoal canister. Place your fuel hose on that red nipple and you are done. It really is that simple. No error codes, no nothing. Remember, now thru your aux tank is the "venting," so if you have a shutoff valve to the aux and it is closed, you are going to suck and try to collapse your main tank. Also, if you have a vacuum leak, for example leaving your main gas cap open by accident, you will not suck from the aux tank. Last, but not least, in extreme heat (above 97) it WILL drain, but very slowly. Eric Bray has a slightly more complicated way to overcome this. I haven't bothered, and I've ridden in plenty of extreme heat. Still drained both tanks, but takes forever because the fuel in the main is expanding and actually pushing on the aux fuel instead of sucking. With the above method, when everything is working properly, your fuel gauge will not register any consumption until the aux tank is empty. There is a BB under that red cap that can be removed and it might help. I've done this both ways and it doesn't really make much difference. I've attached a few pics and a link to a writeup someone posted on adv. Sadly, I think the pictures in the adv forum are gone.

Most of us do not install the shut off valve but it is nice to have if you want to remove the AUX tank for some reason. If the AUX tank has gas in it a shut valve would make it easier to remove the AUX tank so gas does not run out the fuel line.

The fuel pump in the main tank creates enough suction to pull the gas from the AUX tank.

Normally if you fill both tanks the fuel gauge will show full until all of the gas is drained from the AUX tank.

I have a 3.4 gallon AUX tank made by Boyd Welding and it is mounted where the passenger seat goes. I used angle aluminum to moun the AUX tank to the passenger grab rails.

Check this link.

https://advrider.com/f/threads/camel-tank-install-on-the-big-boxer.1155868/page-1

Some photos that also will help.

AUX tank line goes on this red barb that is the vent for the main tank.








AUX tank specifics

 

Kim Leeson

Selfie Stick King
Premier Member
IBA Member
#5
Thanks Greg, that sounds like a nice clean system, we don't have the charcoal canister in the UK, but obviously, we have the same red filler neck.
I take it the second pic is the 'BB' you mention, not sure what it is, but you mention it works either way...thank you.
 

Greg Rice

Premier Member
IBR Finisher
#6
Thanks Greg, that sounds like a nice clean system, we don't have the charcoal canister in the UK, but obviously, we have the same red filler neck.
I take it the second pic is the 'BB' you mention, not sure what it is, but you mention it works either way...thank you.
Yes, that is the BB. I removed mine to limit any chance it could reduce the flow.
 

Greg Rice

Premier Member
IBR Finisher
#10
I ran the fuel line under the seat and then under the gas tank up to the front of the tank and then up the neck. You have to remove the center piece of plastic to get to the red barb were you connect the fuel line.

I am going to upload a photo that shows the fuel line running under the gas tank.
 
#12
I ran the fuel line under the seat and then under the gas tank up to the front of the tank and then up the neck. You have to remove the center piece of plastic to get to the red barb were you connect the fuel line.

I am going to upload a photo that shows the fuel line running under the gas tank.
Thanks greg, did you put a clamp on the plastic barb?
 
#16
I have never felt the need for an Aux tank on my GSA with nearly an 8 gallon main tank; but this set-up is so ridiculously easy; I might need to readjust my mindset. Thanks Greg.
 

Marc11

Premier Member
#18
You run a 1/4" I/d line. Be VERY careful how you run your lines, any tight turns or bends can restrict flow, which WILL but a strain on your fuel pump and WILL burn it out in under 11 days/11k miles.

Same for the vent line and using a filter. Any restrictions will cause strain on the bikes fuel pump.

I'd recommend no filter and running the aux tank vent back to the OEM cannister to reduce the chance of sucking in water, dirt and becoming restricted.
 
#19
You run a 1/4" I/d line. Be VERY careful how you run your lines, any tight turns or bends can restrict flow, which WILL but a strain on your fuel pump and WILL burn it out in under 11 days/11k miles.

Same for the vent line and using a filter. Any restrictions will cause strain on the bikes fuel pump.

I'd recommend no filter and running the aux tank vent back to the OEM cannister to reduce the chance of sucking in water, dirt and becoming restricted.
Would a second in line pump work in this same set up ?