Fuel flow question

[ianc]

I'm adding an additional fuel tank to my Mercedes Vario along with some addition plumbing to allow electric switch over between the tanks plus an inline filter with a water trap. The new tank location means an additional 4-5m of 8mm piping (including the return circuit). The question I have is: Will the existing fuel pump have the strength to still circulate the fuel? and if not, would a Facet pump like this (see link) give sufficient flow?

http://www.ebay.co.uk/itm/UNIVERSAL...636?pt=LH_DefaultDomain_3&hash=item233250d544

 

[canals1164]

Ian
Are you switching the return from engine to the tank as well? I have a secondary tank which is used to top up the main tank, this means that you can leave all standard fittings and gauge with just a transfer pump to top up when needed. Simple but works!

 

[ianc]

I want to be able to use Bio Diesel in the secondary tank and so do not want it to mix back into the main tank.

Here's the the gubbens for doing the switching and filtering. I still have to add a timing circuit which will wait for the circuit to purge before switching the return.

 

[Neil]

Hi Ian
I am at the same point, I have the second tank in place but still thinking about the best way to plumb it all in.
My first thoughts were that the auxiliary tank would simply feed the main tank via a small lift pump.
You have now got me thinking that keeping them separate could be better.
I had completely forgotten that the fuel return will go back to themain tank.
Keeping them separate would stop different fuels mixing .
Is there a problem with mixing normal diesel and bio?

I have also made a mistake in that my first filter out of the tank is a Separate 30 micron. The fuel line then splits to the engine pump and the eberspacher.

My new steel tanks appear to have had a film of preserving lawyer or freeze in it and it clogged the filter up within no time.
This made me realise that you need to put a sacrificial pre filter in line before your good one.
One dose of crap fuel could right of your good filters in minutes.
I am fitting a clear bodied 120 micron strainer just before the separate. They cost nothing and should protect the good filter

You have got me rethinking the aux tank now

Neil