Fuel Polishing

[SolaceinOly]

Fuel Polishing? is this referring to Gasoline as well as Diesel?
I have a Gas engine older than dirt (Grays,Aeroceanic,Continental depending on where you get parts) with a Racor already on it and a neighbor tells me in order to "polish" my gas I should install another filter after the Racor? I was hoping for some advice from anyone with experience in "polishing" or give me there opinion if another fuel filter would be a good idea or is it too redundent or a strain on my electric fuel pump? Any advice would be great.

[gettinthere]

Typically a fuel polishing system is a separate pick up at the very bottom of the tank pulled by a separate, dedicated pump running the fuel through a separate filter and then back to the top of the tank.

[delmarrey]

Polishing is mostly for diesel.
Gasoline can be polished but it still loses chemicals over time making it sluggish. But by mixing it with fresh gas boosts it.

Diesel polishing is to get out any settlements, bacterias, sludges and water. And with some additive will boost it.

I've built my own polishing system with a washing machine motor connected to a vane pump that runs it through diesel filter (30 micron) w/water separation.

Each spring I pump my fuel tanks through the scrubber out into a separate fuel containers and then through the scrubber back into the fuel tanks after I've inspected the tanks.

And now with the biodiesel added I have to be even more diligent about the fuel cleanly-ness.

One can buy polishing systems for installation but one has to have the room to install all the gear. Plus the cost of all the filters can get expen$ive.

[DeepFrz]

What the others have said except the return to the tank should be to near the bottom of the tank not the top.

[dave777]

Originally Posted by delmarrey

I've built my own polishing system with a washing machine motor connected to a vane pump that runs it through diesel filter (30 micron) w/water separation.

Can you tell us more about your polishing system? Parts used, pictures if possible.

[Pete7]

Dave, I made a portable one up a couple of years ago and use it each Spring.

Standard CAV filter and a small fuel pump from e bay that circulates about 110 lph.

Fuel take off is from the bottom of my tank via the sight tube.

Pete

[Brazil]

Originally Posted by DeepFrz

What the others have said except the return to the tank should be to near the bottom of the tank not the top.

Can you tell me why do you think return should be at bottom? Thanks

[roetter]

I built my own system for my sail boat.

The tank had one unused connection port. I got a fitting for it with a copper tube that can slide up and down in the fitting until the nut is tightened. I bent the copper tube end that would be lowered into the tank into a big arc of about 60 degrees. I then inserted the fitting in the tank and then slowly slid the tube down until I could feel it hitting the bottom of the tank. As it is bent in a large arc it springs slightly, thus when I tighten the fitting to prevent the tube from sliding upwards, the pickup remains right at the bottom of the tank. I then led a hose to a Racor filter with glass bowl. From the filter back to an electric diesel fuel pump bought at an auto-parts shop and into a T-fitting into the return line of the diesel from the engine.

My boat was just 2 years old when I first did this. FI could not believe my eyes, as for the first 5 minutes I just saw black gunk going through the glass bowl at the filter. I now run it for a few minutes every month or so and have not seen any major contamination anymore. The diesel in the glass bowl of the Racor has the colour of honey.

The last thing I want to happen is that in a storm the motion of the waves kick up the muck at the bottom of the tank and block the engine fuel filter. I sleep a lot better with my home made fuel polisher..

[DeepFrz]

Return should be near the bottom of the tank for two reasons. First it prevents or minimizes oxygenation and air entrainment of the fuel and secondly it helps to stir up the precipitates that settle to the bottom of the tank.

[delmarrey]

Originally Posted by dave777

Can you tell us more about your polishing system? Parts used, pictures if possible.

Not much toit! Just an external truck screw-on diesel filter with the mount and a rubber impeller pump (nitrile impeller) attached to a washing machine motor, joined with a flexible coupler.

One thing I found out this last summer, is it needs a cleanable inline screen before the pump. I sucked up a screw big enough that it stopped the pump. I think during its construction it got dropped in.

Basically, the start of every season I scrub the fuel that's in the tank. Anything new should get caught by the motor filters. I stick the metal tube in the tank with clear tubing and pump it thru the filter into jerry cans. I check out the tank thru the inspection cover and then pump it all back in thru the filter again.


.

[delmarrey]

Originally Posted by DeepFrz

Return should be near the bottom of the tank for two reasons. First it prevents or minimizes oxygenation and air entrainment of the fuel and secondly it helps to stir up the precipitates that settle to the bottom of the tank.

Just a note. It should come in thru the top with a down tube rather then a fitting at the bottom, for safety. The return shouldn't be anymore then 3-4 psi, depending on the motor. The same with hydraulic tanks.

[DeepFrz]

It should come in thru the top with a down tube rather then a fitting at the bottom, for safety.

Absolutely.

One thing I found out this last summer, is it needs a cleanable inline screen before the pump. I sucked up a screw big enough that it stopped the pump.

Del, why don't you pull the fuel through the filter and then to the pump? Would eliminate the need for a screen.

[rebel heart]

A clean tank and clean fuel doesn't need to be "polished", and "polishing" won't clean a tank.

Drain the tank, open it up, wipe it down with paper towels, fill it up and use an approved biocide. Takes a day and really isn't that hard.

[delmarrey]

Originally Posted by DeepFrz

Absolutely.


Del, why don't you pull the fuel through the filter and then to the pump? Would eliminate the need for a screen.

This pump has quite a bit of suction. Filters are meant to be pressurized, it might collapse the paper element, but it might be worth a try. Maybe if I plumb it backwards.

[delmarrey]

Originally Posted by rebel heart

A clean tank and clean fuel doesn't need to be "polished", and "polishing" won't clean a tank.

Drain the tank, open it up, wipe it down with paper towels, fill it up and use an approved biocide. Takes a day and really isn't that hard.

My tank inspection hole isn't big enough to get my hands in. Big hands!

It's any condensation or bacteria growth build up over the winter that I go after. If it gets scrubbed thru the 10 micron scrubber, then surely the 5 & 3 micron motor filters will catch the rest w/o plugging them up right away.