Steven Shelikoff wrote:

Well, now I have to ask why the pump should be before the finer stages
of filtration.

Because you can install canned filters which are rated for
high pressure downstream of the pump, on the pressure side.
The filters on the suction side are fairly coarse, produce
little resistance to flow until clogged, and can perform the
initial separation of water and solids.

wouldn't matter where the pump is. Of course if it can't do that (not
enough suction for all the stages before it) then you'd have to move the
pump up in the stream like you suggest above.

If the pump was upstream of all filters, so that it sucked
through them all, the differential available is pretty low.
That is why most installations use Racors on the suction
side for the reasons I have given and then the final filters
are can filters on the pressure side.

We seem to have gotten away from the polishing thread here
but there really isn't much difference.

One thing to keep in mind, this process is not designed to
conserve on filters, it is supposed to clean fuel.

Rick