As part of my trying to get smarter than I am (not hard!) about fuel
and oil issues, in the course of searching for info about the
oil-change-into-fuel-tank issue, I stumbled on discussions of fuel
polishing.

Our setup is now such that the pump is the last thing before it returns
- it sucks through the two filters in series, with the vacuum gauge in
between the pump and the filter line, drawing the fuel from the same
supply point as the engine. We have two honking big 30 and 10 (in
series) micron filters driven by a 3.5gpm Walbro pump, and monitored
with a gauge, for the polisher. I've run that enough, now (at the
slip, so no slosh, yet) to have circulated the fuel several hundred
times. No change in the vac gauge, yet.

I debated doing a separate feed, but decided that getting the fuel from
the same point as the engine in the tank would have the best likelihood
of making sure that what the engine pulled would have first been
polished.

That's because - as above - I'll have run the polisher excessively, as
well as all the time the engine is running, plus any time the batteries
are charged and we're sailing, as the wind generator will more than
take care of that load (.8A), and it's pulling from the same point, at
least somewhat assuring that that point will get lots of fuel flow, and
by extrapolation, said fuel will have been through the filters many
times.

However, I'm scratching my head a bit about filter sizes. In one of
the threads I read, it was observed that a 30 micron filter will also
catch many smaller particles, and ditto the 10. After enough passes,
effectively, it appears that the fuel will be down to something on the
order of 2 microns, perhaps even less.

One of the assertions I've recalled seeing in the past (not that it
showed up in this recent search) was that multiple passes, as the
filters eventually started filling with catch product, yielded finer
filtration as time went on. That makes sense to me - I suspect the
only problem would be how fast the filter got so full as to inhibit
transfer through it. In my case, the filters are very big - the cases
are 3.5x11 inches - so I expect it will take a very long time to cause
the vacuum to rise enough to warrant a change.

So, I'm wondering if that postulate is right - that lots of running
will make my tank have a net particulate of only tiny (relative, of
course!) size? Other commentary in the past showed very extended
standard filter changes with this sort of arrangement, apparently as a
product of this polishing.

I have this dual Racor setup, as well. I have only the filter which
came in the new one (10), and some spares of the original on the boat
(30), plus a spare of the engine filter (2). I'm about to buy spares
for all of these as part of our provisioning.

So, more head scratching, from a very long-ago thread in this space,
someone suggested 2 was appropriate. Certainly, with the dual setup I
have now, swapping over and doing a filter change is easy - much easier
than changing the engine filter (2) and repriming, etc. I had been
going to do 10s in the Racors, on the presumption that the polishing
had reduced it to that level, and likely I'd never have to change them,
anyway. However, if all the above is right, perhaps I'd be better off
with 2s, on the likelihood that even those would not likely need
changing very often, having had the fuel polished to that or better
levels, already, by the time it got there.

So, two questions from all this.

1) Is my polishing setup appropriate - is the 30 followed by the 10 a
good practice?

2) For those who have done it, or if there's still a professional
filtration person looking into this group who can give empirical
commentary vs usage experience, will I be changing 2s in the dual Racor
setup often, or will the polishing likely reduce the particulate to
that or below?

And, doing a Columbo, thinking of something I forgot...

I also have an electric priming pump, operated by a momentary push
switch. However, when we bought the boat, it was next to the engine,
after, not before, the Racor. Logic suggests it should be in front of
the Racor, to refill it, before priming, rather than sucking all that
air into the system. Or, is that not a problem? I've never changed a
Racor, so I don't know what's really involved, but I can say for sure
I'm not enthusiastic about having to pour fuel into the body as is
suggested in the instructions.

My apologies for asking what might be stupid newbie questions - but
I've had the good fortune never to have to deal with a stopped diesel
engine, and would like to keep it that way. A very well equipped tool
kit is just fine with me if it never leaves the locker...

Thanks for putting up with me - likely there will be a flurry of this
sort of thing as we approach, and then do, our sea trials...

L8R

Skip, installing and filling more engine stuff so we can fire it up and
service it soon...

Morgan 461 #2
SV Flying Pig KI4MPC
See our galleries at www.justpickone.org/skip/gallery!
Follow us at http://groups.google.com/group/flyingpiglog and/or
http://groups.yahoo.com/group/TheFlyingPigLog

"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail
away from the safe harbor. Catch the trade winds in your sails.
Explore.
Dream. Discover." - Mark Twain