Should not put any pressure on the engine if the return line is properly
sized for the pump you use.  The fuel will take the path of least resistance
and flow to the tank.

Ray B

Right. I T'd into both my supply  and return lines for mine. I just shut the
feed and return lines for the main and genset when I'm polishing. The pump
pulls from the supply line, through the filter then sends it back through
the return lines to the tank I'm polishing. Make sure you always return fuel
to the tank you pulled it from.

Keith
__
'No, Eureka' is Greek for this bath is too hot.'' -- Dr. Who
----- Original Message -----
From: "Bill Martin" martinwj@earthlink.net

Bill wrote:

As Ray added the fuel will take the path of least resistance and return
to the tank.  One thing to keep in mind:  My last boat was a twin gas
Chris Craft that the PO had converted to a single diesel (120 hp
Lehman).  He reused the original tank and made the port fuel line the
diesel supply and the starboard one the return line.  The top of the
tank was about a foot higher than the top of the engine.  Since both
fuel pick ups went down to the bottom of the tank, when the tank was
full there was pressure on the diesel return line back towards the
engine.  No problem until a small leak developed in the fuel return
manifold under the valve cover and the crankcase filled with diesel.  I
fixed my problem (after it happened twice) by cutting off the return
pickup flush with the top of the fuel tank.  I could see how Bill's fuel
polishing set up could cause a similar problem.

Cheers,
Gregg McKay
First  Look (Tollycraft 37)
Victoria, BC

I built a fuel polishing system for my Ocean Alexander 486.  Used the
Gulfcoast large filter that uses a roll of Bounty paper towels.  Disuse
of the boat had caused the fuel to grow bugs and caused floating stuff
in the tanks (black snot?). I struggled with the return and pick-up
system and methods as I have two 350 gl tanks and wanted to use the pump
to balance the tanks as I have a natural port list when all are full.
My tanks had an extra plug in the bottom that became the pick-up and
then I modified the sight glass upper fitting with a Tee for the
return.  I did not want to fuss with the main engine lines to cause
future unforeseen problems.  Using a 12 hour timer on the system allows
the fuel to be polished when I am gone from the boat.  Just be careful
not to pump from one tank and overfill the other.  Big mess!  About 40
hours and three towel changes have the fuel clean as new.  I used a lot
of ideas Capt Will put forth in his write-up.  If anyone is interested I
can e-mail pictures of the completed system, contact me direct.
By the way, my boat had a combination of NPT, BSP, and BSSP fittings.
Found McMaster Carr .com as best source for fittings and valves.

Robert Hoffman
Legacy (486 Ocean Alexander)
St. Louis, Mo.

on 1/5/04 8:28 PM, Robert Hoffman at bobhof@sbcglobal.net wrote:

Robert,

I would be interested to know the material your tanks are made from and how
long the fuel sat in the tanks before going bad. Thanks.

Bob

R C Smith Jr
M/V MARY KATHRYN
1977 Hatteras 58 LRC
Marathon in the Florida Keys

In the past 3 years, I put less than 50 hrs per year.  No new fuel for 2
years.  Even though I put biocide in each winter, the black stuff grew.
The tanks are aluminum.  When I installed the polishing system. the
plugs I used in the bottom of the tank allowed me to see a small amount
of the tank surfaces.  I had both hard particles and a coating.  I also
put a fuel treatment in and ran the polishing system for 40-50 hours on
the old fuel.  It seemed to desolve the build-up and trapped it in the
Gulfcoast filter.  By the way, I have large Racors as the primary engine
filters, and when I changed the secondary filters on the Cats,  they
showed no sign of problems.  Use 2 Micron filters in the Racors.
All goes to show you, boats are made to be used.
Robert
On Tuesday, January 6, 2004, at 07:49 AM, R C Smith jr wrote: