Filling an auxiliary diesel tank

02 Nov 2012 21:10 #1 by dandjcr
dandjcr created the topic: Filling an auxiliary diesel tank
Forum Home > On the Road > Filling an auxiliary diesel tank

Tony Lee
Posts: 540
The existing camper has Webasto cooktop and hydronic heating system and the diesel comes from a 30 litre SS tank that is filled by an electric fuel pump through a separate fuel filter.
This means that the fuel has had an extra stage of filtration and is less likely to be contaminated by dodgy supplies. The overflow goes back to the main fuel tanks so I can run the electric pump occasionally to make sure the fuel in the aux tank is fresh.
There was a drain so in an emergency, I could transfer any fuel from that tank to the main tanks.

New design has a 90 litre tank under the dinette along with three water tanks and while it will feed the webasto units, it will also serve as an auxiliary tank giving me a total capacity of around 300 litres.

I would like to make sure this tank stays full at all times and its location means that it isn't all that practical to be able to fill it from a bowser.

I could use the electric pump to fill the auxiliary tank up by turning it on 30 minutes before a normal fuel stop, but another way would be to cut the return fuel line between the engine and the fuel changeover valve, extend the line to the auxiliary tank and then run the taank overflow back to the fuel changover valve and hence into the main tank as usual.

This would have the advantage of always keeping the auxiliary tank full of fresh filtered warm diesel - ideal for feeding the webastos.

There would also be valves to bypass this filling system plus run fuel from the aux tank to the main tank.

Anyone have any thoughts on whether this slightly increased back pressure (because of the longer return line) would cause any problems with the engine fuel system. If it is likely to be back-pressure sensitive, I could just run the extended lines in hose the next size larger.

November 6, 2011 at 3:53 PM

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