LaBomba182 wrote:

Subject: Fuel transfer/polishing pump
From: "Doug Dotson"





Makes sense, but there is quite alot of evidence out there that
a polishing system is a good thing to have. I can't really
increase the size of my on-engine filter. I could increase the
size of the Raycor, but at the pore sizes I run (30 micron) in it make it
necessary to change the on-engine filter regularly as well.
Bigger Raycor won't fix the problem.



What's the GPH on your engine?

If you go to a larger Racor you could easily change to a smaller micron
element. It fact, I have never understood why people don't run as small a
micron element as they can in the first filter after the fuel tank. Why let
anything near the micron size of the engine mounted filter get to that filter
at all?

Capt. Bill


You don't want too fine a filter on the suction side. On Yanmars (and
others), the lift pump can fail sooner due to the restriction. The idea
is to do the cleaning in stages: 30 micron before the lift pump, 10
micron just before the high pressure pump. That said, we used 10 micron
Racor elements for 8-9 seasons and 1000 hours with no significant ill
effects except when we got a shot of algae. The on-engine filter never
had any significant dirt on it (or in the bowl). That didn't change much
when we went to 30 microns, as it happens.

Note: We were able to limp home when the last filter on board clogged up
during the algae incident: Pulled the filter and gently brushed junk off
of the surface, and drained and cleaned the bowl (again). For a couple
of hours, we could only pull half revs, but the fuel cleaned up nicely
at reduced flow and (after draining the dead bodies from the bowl again)
we had full power for the rest of the season.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/