Twin fuel tanks - a different approach

**gromit** · 31st July 2014, 05:37 PM

My Defender Tanami is fitted with a sill tank (LRA).
It's controlled by a 3-position rocker switch. Position 1 main tank level, position 2 sill tank level, position 3 main tank level and start lift pump to fill main tank.
There is both a level sensor in the sill tank and also a second sensor at the bottom that shuts down the pump if the level drops too low (because you are displaying the main tank level while pumping). I did work out the circuit many years ago, from memory it only needed two relays.

My Series 1 has two tanks, the standard underseat and an additional one under the floor of the tub.
Switch on instrument panel selects which tank.
Position 1, Facet pump delivers fuel from main tank, gauge displays main tank level.
Position 2, Second Facet pump delivers fuel from the additional tank, gauge displays additional tank level.
The two Facets are Tee'd together, the non-return valve in the pump stopping backflow into the other tank.
Apart from the addition of a fuel pressure regulator (because a Holden carby is fitted) it's been like this for over 20 years.

Both of these solutions need a separate filler for the second tank.

The second option is easiest, just a changeover switch and 2 Facet pumps and a bit of wiring.
Here is the pump setup (& regulator) on my series 1.

Colin

**Homestar** · 31st July 2014, 07:51 PM

Originally Posted by chazza

My thoughts;
1. The passenger only has to vacate their seat in a S1 - presuming that an extra tank has been fitted - all the later cars can have an external filler on both sides, as the Army did.
2. The Army conversion had a switch near the fuel gauge, which allowed the level of both tanks to be read at any time.
3. Changing over was very simple using the cock below the seat cushion; however; I grant that a solenoid instead of a cock, would work just as well and could be wired to the instrument switch. Bear in mind though, that if a solenoid fails for any reason, the fuel cannot be accessed, except by siphoning.

My initial thoughts on reading the post, was that if one tank gets holed, both tanks will drain, which will not happen if there is no balance pipe.

Let us know what you do Gav - I enjoy a bit of inventiveness,

Cheers Charlie

Hmmm, my old 2a had the fill point under the seat, and the second tank I have now - out of a series 2 has the same. That will be gone anyway. Yes, a hole in a tank would be a bad thing and drain both, but no different from running 1 tank and holing that.

The Venturi pump turned up yesterday - works very well and pumps much more than I thought it would. Still have to do some testing at the actual levels it will run at as it can't draw from much of a head height. In reality it only needs to pump marginally more than the engine is using, which it should do fine.

**Lionelgee** · 31st July 2014, 08:46 PM

Originally Posted by bacicat

The Venturi pump turned up yesterday

Hello Bacicat,

Can you please let me know what brand - manufacture and size venturi pump you bought?

I think Banjo over in the Parking Lot Section under Embarrassment had a template for installing the passenger side filler point.

Kind Regards
Lionel

**Themadmob** · 8th August 2014, 02:35 PM

Hi Sitec

DO you have a diagram or photos ... I am interested in dual tanks as well

**Homestar** · 8th August 2014, 03:04 PM

Originally Posted by Lionelgee

Hello Bacicat,

Can you please let me know what brand - manufacture and size venturi pump you bought?

I think Banjo over in the Parking Lot Section under Embarrassment had a template for installing the passenger side filler point.

Kind Regards
Lionel

Ebay.

. It has 8mm barbed ends so fits in perfectly with the fuel system. I have a filter and Facet pump as well, so will be testing it over the weekend.

[ame="http://www.ebay.com.au/itm/Filter-Pump-Metal-/161368306726?pt=AU_Business_Industrial_Medical_Sci entific_Equipment2&hash=item25924cf426&_uhb=1"]http://www.ebay.com.au/itm/Filter-Pump-Metal-/161368306726?pt=AU_Business_Industrial_Medical_Sci entific_Equipment2&hash=item25924cf426&_uhb=1[/ame]

Edit - can't seem to make a link work... Copy and paste this - [ame]http://www.ebay.com.au/itm/Filter-Pump-Metal-/161368306726?pt=AU_Business_Industrial_Medical_Sci entific_Equipment2&hash=item25924cf426&_uhb=1[/ame]

No idea what's going on - can anyone see or use a link here, or see a URL?

**Homestar** · 8th August 2014, 03:06 PM

Originally Posted by Themadmob

Hi Sitec

DO you have a diagram or photos ... I am interested in dual tanks as well

Sitec's system is very good, and very simple. I'll still be looking at if I can do it that way on the series, but my only concern is having the required fittings at the bottom of the tank. They may be prone to damage on the series, not sure yet. The system I showed it the OP all goes in and out at the top of the tanks.

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