Alpina extended fuel tank questions

[slippery]

I am not sure this is the correct section, if it is not please move.

I am curious about how the Alpina extended fuel tank works. Does anyone have one and can help me understand how fuel flows from that to the regular tank? Is it gravity or does it have a transfer pump?

Also when you fill up, gas goes to the regular tank and after its full it starts filling up the extended tank?

I also remember seeing that the fuel gauge shows the extra fuel. Is that correct?

Thanks

[roguetoaster]

Not sure how the level sensor/gauge setup works, but I believe the tank is set up with a tee in the filler neck which allows the extended tank to gravity feed and be filled in the normal way.

Personally, I wouldn't want one as I would be worried about the sender/pump seals in the main fuel tank leaking. Also, you need to cut a hole in your E30 to install the filler.

However, I supect the intention is to leave the aux tank mostly empty except when you are doing a long trip.

[e30m3s54turbo]

When you fill main e30 tank it over flows to extended tank. It should come with e30 filler piping. The e30 filler piping should come with a T the filler to the truck. You will need to cut a hole in truck to filler piping and breather hose.

[slippery]

Ok, I see. So it is gravity feeding the main tank.

I was not aware of the hole that needed to be cut.

[slippery]

Btw, thanks guys for the explanation.