Adding A Fuel Polishing Diversion Loop

[aybabtme]

I've had some issue with my diesel tank getting dirty with water and growth, despite taking care with keeping the tank full and with biocide when leaving the boat for long periods. The boat came with a Racor 115 primary filter, which I find makes it hard to debug since it doesn't have a see-through bowl. So I'm upgrading the filter with a Racor 500MA.

As I'm installing the new filter, I was also removing an old diesel line that was left from PO for a diesel heater. This part of the system had a Walbro 2402 pump on it, so it got me thinking about reusing the pump and some fittings to create a diversion polishing loop. The pump doesn't appear to work, but I nonetheless want to try and add a diversion loop in the system that would pump diesel through the Racor 500MA on a schedule when the engine isn't running, to try and keep fuel in the tank as clean as possible.

Here's what the current fuel line looks like:

And here's what I have in mind:


Notes:

• the Racor 500MA is rated for 60GPH, a max allowable pressure of 25PSI and creates a pressure drop of 0.25PSI when clean. Docs.
• I'm thinking of getting one of the Walbro FR line pumps.
• The fuel lines are 1/4".
• Power is not an issue. I can dedicate 100Ah to this per day without a problem.

Do you see any problem with this design? Should I have some check-valves on the return lines? Do you recommend a specific pump?

[CarlF]

I have a similar polisher but instead of a "T" I have a three way valve.When I polish I first turn the valve to select the polishing loop and then turn on the pump (which is a Walbro FR).

That said, polishing may not fix your problem. The sides of the tank may be covered with growth that break free when the boat is in a sea.

The best fix might be to bring in a professional tank cleaning company. They have high pressure equipment that can blast the tank sides.

[aybabtme]

I'm cleaning the tank too, and will replace it with a Ronco plastic one if it's in bad shape.

[sailah]

My experience with a polishing setup similar to yours:

-Don't use the same pickup as your engine. The polishing pump will pull fuel and is likely stronger than your enigne lift pump. In my case it would almost stall the engine. I installed a separate fuel pick in the tank and it works great.

-You can use the same return

-If you install a 3 way valve or other valving mechanism you can also provide filtered fuel to your engine if your lift pump fails. I did it with a T fitting and ball valves. I also use this to fill the Racor after filter changes so the engine does not need to prime it.

-This is the pump I run, been using it for 100s of hours of polishing. Works great. https://www.amazon.com/Carter-P4070-.../dp/B000CIQ5DG

-I wired mine into a 3 way switch so that i can manually turn it on, or run it whenever engine is running which is what I normally do. Even with frictional losses I'm still turning the tank over numerous times.

-I run 2 large Shelco industrial filter bodies as my filters. 1 is 10 micron, the other is 5 micron. The pump is setup in series between these filters so it never sees dirty fuel, it passes thru 10 micron filter before pump. The filter cartridges are $6 and about 10" from McMaster Carr. I haven't changed them in a couple years and I still get good flow.

-A side benefit of a polisher with separate pickup tube is that I can empty my tank in 30 min if I ever decided I needed to do that.

I have noticed that since polishing my Racor 10 micron filter looks almost new. I still change it every season out of habit. I also see almost no vacuum on Racor gauge either. No sediment or water is evene in Racor bowl. I feel like polisher gets everything just because it's greedy.

[aybabtme]

How often do you change the filters in series with your polishing pump?

[steve77]

I bought my electric fuel pump (by Facet) from NAPA about 5 years ago and it has worked great. There was another thread on this forum recently asking if fuel would flow through these pumps if they are not energized and the answer was yes. I know mine does.

Since the pump will allow flow when it is not running, then I would install the pump between the primary and secondary filters, with a three way valve to select whether the discharge of the pump goes to the secondary filter or the return line. As Sailah said, this will allow you to use your electric pump to fill the secondary filter and keep you from using the little priming handle on your engine. For me, that is a real convenience. With the three way valve on the pump discharge, I don't think you will need to add any other valves.

For convenience I installed an ON-OFF switch right next to the pump and within easy reach of the primary and secondary filters. (My system is more complex than yours and allows me to use the pump to fill the primary filter, also). When using the pump to fill the filters, It is easy to turn off the pump without having to get up and go the the electrical panel and turn off the breaker. This keeps me from spilling fuel into the bilge while trying to shut off the pump.

Cheers!

Steve

[zboss]

The Manta catamarans came equipped from the factory with a fuel purification system which used a timer and a resuable RCI fuel purifier. In fact, they didn't even come with a prefilter and only with the engine mounted primary fuel filter. Basically a design much like you have designed but with a timer switch that lets you run the purifier over a number of hours.

The advantage of the RCI is that you never need to replace media.

https://www.rcitechnologies.com/products/fp-50/

[CarlF]

Looking at the OP's post again, it's unlikely that a fuel polishing system is going to help.

If he's been adding a biocide for some time, then everything is dead. After a few tanks the stuff in the fuel would have gone out though the filters.

My guess is that he has growth stuck to his tank walls. Each time he goes out in rough water some falls off. Since he won't be polishing then, it risks clogging his filter underway.

The best thing would be to hire a professional tank cleaning company. They have the equipment to knock everything off the walls not just circulate the fuel. Alternately, he can drain the tank and put in a large enough access port in the tank top that he can really reach around inside with cleaning pads on a pole

There's also a chance that the place he's getting his fuel has a problem with their tanks. Next time he fuels he should fill a clear glass with fuel and let it sit for 15 minutes to separate. Water and sediment will be obvious.

[thinwater]

Originally Posted by zboss

...The advantage of the RCI is that you never need to replace media.

https://www.rcitechnologies.com/products/fp-50/

The disadvantage is that RCI is a hydrocyclone and will only remove materials that are substantially heavier than diesel. Great for water, not so much for bugs and gum. It is not a filter.

[timeout2]

Treat your tank with biobore. Trace down any source of water. That should eliminate any problems. You should not have water in fuel tank. Using your primary filter as your polishing filter isn't the best solution. Use a separate racor 500 filter with either a walbro or holley pump. If possible try and make the polishing system a separate and redundant primary filter. Fuel rarely needs to be polished. Certainly not on a routine basis. If there is a problem, find the source.

[Dymaxion]

A laymans question: is it good practice to use a main engine filter as the polishing filter? Think I'd prefer to add a filter for polishing only and not risk clogging a more crucial filter.

[sailah]

Originally Posted by aybabtme

How often do you change the filters in series with your polishing pump?

I used to change them every year out of habit of changing all filters. But everytime I would pull them out they looked new. I still get exact same flow so I have probably left them in there for 2 years now. I'll do it at end of this season. I likely have 300 hours of polishing on these as they are run every time my engine is running (125 hours/season), plus I polish for a couple days continuously before I remove winter cover in the spring.

This is what I use for filters:

https://www.mcmaster.com/9982T13

[sailah]

Originally Posted by Dymaxion

A laymans question: is it good practice to use a main engine filter as the polishing filter? Think I'd prefer to add a filter for polishing only and not risk clogging a more crucial filter.

Your main engine filter like a Racor 500 is basically doing that already. There isn't much fuel moving through it though. You can add a Racor gauge handle that will show you when the filter is getting clogged due to high vacuum. At that point you either need to shut down or hope it doesn't shut you down.

Lots of people make a polisher using exact same Racor 500 filter body as you have a standard filter you can get anywhere and shares with main engine. But it's plumbed as a standalone unit. I would not use the same filter as your main engine and somehow plumbed in parallel with a polishing unit. For the simple reason that it could introduce air into the system and the polishing pumps are much stronger than your lift pump. In my case, just using the same pickup tube as engine was enough to starve my diesel so I added a separate pickup tube.

So yes, to your question, I think polishers work best as standalone units. I have valves on mine to act as a backup to my Racor if I clog it. I can throw 2 valves and keep the diesel running on 5 micron fuel until I get around to swapping the Racor. In theory it works, and I've tested it. But never had to use in on a lee shore type situation.

[JRSHAW]

Originally Posted by sailah

My experience with a polishing setup similar to yours:

-Don't use the same pickup as your engine. The polishing pump will pull fuel and is likely stronger than your enigne lift pump. In my case it would almost stall the engine. I installed a separate fuel pick in the tank and it works great.

-You can use the same return

-If you install a 3 way valve or other valving mechanism you can also provide filtered fuel to your engine if your lift pump fails. I did it with a T fitting and ball valves. I also use this to fill the Racor after filter changes so the engine does not need to prime it.

-This is the pump I run, been using it for 100s of hours of polishing. Works great. https://www.amazon.com/Carter-P4070-.../dp/B000CIQ5DG

-I wired mine into a 3 way switch so that i can manually turn it on, or run it whenever engine is running which is what I normally do. Even with frictional losses I'm still turning the tank over numerous times.

-I run 2 large Shelco industrial filter bodies as my filters. 1 is 10 micron, the other is 5 micron. The pump is setup in series between these filters so it never sees dirty fuel, it passes thru 10 micron filter before pump. The filter cartridges are $6 and about 10" from McMaster Carr. I haven't changed them in a couple years and I still get good flow.

-A side benefit of a polisher with separate pickup tube is that I can empty my tank in 30 min if I ever decided I needed to do that.

I have noticed that since polishing my Racor 10 micron filter looks almost new. I still change it every season out of habit. I also see almost no vacuum on Racor gauge either. No sediment or water is evene in Racor bowl. I feel like polisher gets everything just because it's greedy.

Can you tell, me what pick-up and return you added???
Can't seem to find one I can add without removing the tank

[JRSHAW]

Originally Posted by sailah

My experience with a polishing setup similar to yours:

-Don't use the same pickup as your engine. The polishing pump will pull fuel and is likely stronger than your enigne lift pump. In my case it would almost stall the engine. I installed a separate fuel pick in the tank and it works great.

-You can use the same return

-If you install a 3 way valve or other valving mechanism you can also provide filtered fuel to your engine if your lift pump fails. I did it with a T fitting and ball valves. I also use this to fill the Racor after filter changes so the engine does not need to prime it.

-This is the pump I run, been using it for 100s of hours of polishing. Works great. https://www.amazon.com/Carter-P4070-.../dp/B000CIQ5DG

-I wired mine into a 3 way switch so that i can manually turn it on, or run it whenever engine is running which is what I normally do. Even with frictional losses I'm still turning the tank over numerous times.

-I run 2 large Shelco industrial filter bodies as my filters. 1 is 10 micron, the other is 5 micron. The pump is setup in series between these filters so it never sees dirty fuel, it passes thru 10 micron filter before pump. The filter cartridges are $6 and about 10" from McMaster Carr. I haven't changed them in a couple years and I still get good flow.

-A side benefit of a polisher with separate pickup tube is that I can empty my tank in 30 min if I ever decided I needed to do that.

I have noticed that since polishing my Racor 10 micron filter looks almost new. I still change it every season out of habit. I also see almost no vacuum on Racor gauge either. No sediment or water is evene in Racor bowl. I feel like polisher gets everything just because it's greedy.

Can you tell, me what pick-up and return you added???
Can't seem to find one I can add without removing the tank
Do you have a schematic of the system you added?
I have a sailboat with a very old but very hard to get to tank