What is this crud?

[lannen]

Okay, I've got my new fuel polishing system up and running. It's basically a 2 micron Racor filter.

I can see the water on the bottom, and the diesel on top, but what is that crud in the middle? It's a creamy looking liquid that resembles foamy spit.

The fuel tank is new. I had the original 70 gallons in the tank and never saw anything in the Racor bowl. I refueled a couple of months ago taking on 30 gallons of diesel. I either picked up water from the refuel, or a leaky deck cap.

I can't positively confirm one or the other. In any event, this is what is coming out of the tank.

Bio-Bore was added at the refueling, none was added with the original 70 gallons.

Any ideas?

[Alan Wheeler]

It's an emoltion of water and the water soluble components of the fuel, like Methanol or Ethanol or what ever you guys have added to the fuel and the additive you yourself added to the mix. Not to worry, your filter system is doing well.
The main thing is that the fuel itself is clean and you have no evidence of growth of any kind.
First time I have seen what is called "red diesel", Red ain't it.

[CSY Man]

First time I have seen what is called "red diesel", Red ain't it.

Bright red it is .

I never buy diesel at the marina, instead take cans to the cas station and get "yellow" diesel...Hopefully all these color additives does not hurt the engine...

[Roy M]

Red color is dye to indicate it is from a source that has paid highway taxes. To prevent trucks from using cheaper marine diesel. It burns just fine.

[lannen]

I purchased this at a marina, and paid about .75 cents a gallon more for it than I could have paid at a shore-side gas station. I'll start buying it on shore and carrying it aboard. Its good exercise, and I really don't burn that much fuel anyhow.

When I first started polishing the fuel it was consistently cloudy. I'm now looking at much cleaner diesel in the filter bowl. It's making a big difference, the new polisher that is... I'm glad I installed it.

[Unicorn Dreams]

Red or Blue diesel is what you get at marinas, meaning that NO highway tax has been charged on the fuel. Natural colored fuel is indicitive of taxed fuel. The coloring won't hurt anything

[Bloodhound]

It looks to me like the water is the middle layer and the emulsion is on the bottom. The bottom layer is most dense, so maybe it contains solid particles, too.

I'm wondering if the fuel was drawn from the tank into the polisher via a dip tube or through a connection on the bottom of the tank, preferably through a connection in a small dimpled sump in the tank's bottom to ensure that all the trash is actually removed from the tank. If a dip tube is used, it seems possible to have what looks like well-polished fuel but still have a layer of crud on the tank's bottom.

By the way, if you're paying more for dyed (aka off-road) diesel than road diesel, you're being robbed. Off-road fuel should be at least 30 to 40 cents per gallon below road diesel. To get non-marina off-road fuel though, you'll need an agricultural exemption permit or such like; otherwise, cheaper to buy at a local service station and lug it to the boat.

[lannen]

The bottom layer is, without a doubt, water. It's the middle layer that is perplexing, but has been tentatively identified officially as 'crud'.

I wish someone would tell the marina's here that they are supposed to charge less...

[Bloodhound]

Then the middle layer may a biological growth or slime. Not all growths are stringy or sheets of brown or blackish organisms, also known as "rag". Slimey, slippery, snot-like material is also common. But I'm impressed that so simple a system collected and separated this stuff.

Is the pump a gear pump or a diaphragm pump? What's the flow rate and micron rating of the Racor? I assume the pump sucks fuel through the filter rather than pushes it through. Are you drawing fuel from the main fuel line to the injection pump or through a totally separate system?

[lannen]

Good morning Bloodhound,

The full story (to include installation) is on this forum at

http://www.cruisersforum.com/forums/...ock-18209.html

The fuel pump was $35 from eBay, 100GPH and no, not a diaphragm pump. Here is the link.

eBay Motors: low pressure electric fuel pump marine,gas,diesel (item 320285935691 end time Aug-15-08 05:31:31 PDT)

I've now got some really pretty clear fuel in the bowl. I'm happy with the results.

[delmarrey]

Originally Posted by lannen

I purchased this at a marina, and paid about .75 cents a gallon more for it than I could have paid at a shore-side gas station. I'll start buying it on shore and carrying it aboard. Its good exercise, and I really don't burn that much fuel anyhow.

You better check with your Dock Master first! Some Marina's do not allow this especially with gasoline. It's a common source of the fuel slicks in marinas. The other is old boats with automatic bilge pumps.

[lannen]

Originally Posted by delmarrey

You better check with your Dock Master first! Some Marina's do not allow this especially with gasoline. It's a common source of the fuel slicks in marinas. The other is old boats with automatic bilge pumps.

When the dockmaster sobers up, I'll ask him.

[donradcliffe]

I'm sure the dockmaster goes home at night.

[David M]

Its also illegal to transport large amounts of fuel on the road without the proper licensing and vehicle.

[Bloodhound]

The threshhold amount requiring licensing and "proper" transporting vehicle may vary from state to state but in this neck of the woods folks transport 100 to 200 gallons of diesel in either drums or a fuel tank on a pickup bed all the time. Used for refueling equipment. Given that most boats don't hold more than 100 gallons, legal transportation doesn't sound like a real issue, although I'd be a lot more circumspect about gasoline than diesel. In any event, I have a couple of real questions...

(1) I've been looking at a variety of diesel transfer pumps and Racor filters (spin-on centrifugal type preferred?) and would like to turn the contents of each 40 gallon tank over at least 3 times during a single polishing. That means 120 gallons total flow per tank which can be done in a couple of hours with a 60 gph pump or in an hour with a 120 gph unit. The pump and filter costs goes up rapidly with size so I'm leaning towards a 2 hour polishing at 60 gph. Sound reasonable? Or is the flow rate too low to stir up the tank contents?

(2) How important is it to balance the pump capacity with the filter capacity? Filter pressure drop doesn't look high enough to be a consideration, so a pump rated at 60 gph (likely rated wide open, against zero head) will probably put out almost that much flow through short large-diameter lines. But if I used a 120 gph pump with a 60 gph filter, what would be the consequence? Poor separation??? Or a pump that is struggling (overloaded) trying to suck too much fuel through too small a filter? Or something else I haven't though of?

(3) I've also seen setups that use two filters in series (NOT in parallel) --- why would anyone do this? Unless the first filter is 10 or 20 microns and the second is two microns, and longer run times can be had. Of course, two parallel filters will double the filtering rate but that might be more cheaply done with a single larger filter.

(4) Does anyone see a problem with piping the system so that the polishing pump can also be used to force fuel through, and bleed, the main injection pump?

(5) What's the best pump type: diaphragm, vane, or gear. All are positive displacement and all should be self-priming to some extent. None of them like having a closed discharge (so some kind of pressure relief might be needed?) but does one of them have better characteristics in this application than the others?

I want to get this one right the fist time, so all input will be much appreciated.