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Discussion Starter · #1 ·
As long as you have a mechanical lift pump on the engine that runs all the time the engine does, why not do this to polish your fuel.

1 Place a tee in the line to the pressure pump and install another line that goes on the vertical barb of the tee.

2 Conect this line with a Y fitting to the return line at least 1 vertical foot above the intake for the pressure pump.

3 Install a on/off valve in the new line just cuz you might need it for bleeding the system although now the system should be self bleeding. If you install an electric clicker pump between the tank and the lift pump you can just change out your filters and install them dry, turn on the electric pump and the fuel will go through the lift pump and fill the filters and back to the tank with out getting air in the high pressure pump with out closing the the new valve.

How much polishing??

Well, that little pump running at no load most likely pump about .1 oz. per stroke. At 2,600rpm that is 260 ozs. per min. or 122 gal.(15,600 ozs.)per hour.

If you deduct the 2 gallons you use at cruse power that still leves 120 gallons per hour for polishing.

So now when you run your engine you are polishing your fuel at a much greater rate than just returning the small amount of fuel that returns from the enjection system and you spent less than what? $100 including the electric pump.

No exrta filters but at the start you may have to change them more often depending on how bad your fuel is.

NOTE: If you just have an electric fuel pump this systen should NOT be used as the pump cannot handle running full time.
Rick :cool:
Mac 25
Southern California
I am not a prejudiced racist sexist bigot. I just hate stupid people.

5,067 Posts
Very ineffectual:
1. extremely low filtration removal efficiency because the contents of the tank are very slow to 'dilute' by the return of such a small volume of 'filtered fuel oil', Most 'return lines' on small diesel marine engines are only a relatively few few cc's per minute flow.

2. causes the primary/second filter set to become more rapidly plugged thus less prone to capture 'slugs' of particles (eg.: particle storms generated from loosening of adhering tank wall sludge, etc.)

3. The more a filter becomes 'plugged' with debris the higher the differential pressure across the filter is needed to deliver the constant flow demand of the engine .... thus makes breakage of the lift pump diaphragm a higher potential.

The accepted way to 'polish' is to use a totally independent filter pump system, that has high volume turnover, uses 'more open' µM filter ratings ... more 'open' filters also means 'very cheap' filters.

Its the fast 'dilution rate' of particles thats occurring IN the tank by 'high turnover' or rapid high volume recirculation of fluid' over and over and over again through relatively low efficiency filters that makes the 'mathematics of reduction' the key to good and very economical 'polishing'; you simply cant get this volume flow from a 'lift pump'. There is a very significant (mathematical, efficiency, cost) difference between 'recirculation polishing' and 'single pass in-line filtration'.
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