On Tue, 25 Nov 2003 17:49:20 -0500, "Doug Dotson"
wrote:

I am designing a fuel polishing and transfer system. My thought
is to use valves to route fuel from any tank to any tank. No
problem with that part. I want to be able to just transfer fuel
or switch in a filter to polish the fuel while transferring. Since
I can select the same tank for source and destination, I can
polish fuel in place as well. The problem comes with the selection
of a pump. I was looking at a Groco or Jabsco pump which seems
good for transfer purposes, but way exceeds the flowrate of the
filter when polishing. A Walbro fuel pump (which I have as a priming
pump now) seems like a good fit for polishing (33 GPH) but will be slow
when just transferring fuel. What happens when a 5.5 GPM pump
(Jabsco) is pushing fuel through a filter rated at 60 GPH (RACOR 500)?

Thanks!
Doug
s/v Callista

Doug,

I just finished building a fuel polishing system for my boat, using a
Walbro pump. I had an old Fram filter (using a Wix element) and
purchased a new Racor. With the system I can change filters while the
engine is running. I can also monitor the filters with a vacuum gage
so I know in advance when a filter is getting clogged. I wanted a
pump that would pull fuel through the system faster than the Walbro so
that I could do more filtering in a set period of time. But beginning
with advice from contributors to this newsgroup and then researching
on my own, I found that the filters would not filter properly if the
fuel were pulled through faster.

So, unless you are willing to purchase very large (and expensive)
filters or several filters in parallel (also expensive), you will need
a pump like the Walbro for fuel polishing and a separate pump for fuel
transfer, if you want to transfer quickly. Also note that the Walbro
is specified for continuous operation while some other fuel tolerant
pumps are not. You need continuous operation for polishing.

To solve the question of only polishing clean fuel while the crud
remained on the bottom of the tank, I have a sealable opening in the
top of the tank and enough room to put in a long stick to stir the
fuel. My 100 gallon tank does not seem to have baffles that would
render this method less effective.

I would have installed a Gulf Coast filter (paper towels) instead of
the old Fram, but I could not afford one. They are damned expensive.
I have no personal knowledge nor objective research results that back
up their claims of superior filtering. I just accepted the hype.

BTW I saw a Walbro pump for sale on E-Bay two days after I purchased
mine, and for half the price I paid. The seller seemed to have
several available.

Lee Huddleston
s/v Truelove