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Autoteacher 07-16-2018 03:21 PM

Fuel contamination
This wad of crud clogged the 1/2id inlet on a racor. What is it? What to do to prevent? The owner used bibor and had the tank cleaned weeks before the incident. Caused engine shut down offshore and boatus tow.

I added another racor 1000 and switch in parallel

Solly 07-16-2018 04:12 PM

No pic.. "URL not found"

kapnd 07-24-2018 02:18 AM

Biobor use often results in increased levels of crud for your filters to digest.
Following use of the stuff, you need to be prepared with plenty of spare filters!
It sounds like the P.O. might be BSing about having the tank cleaned, so the ball is now in your court.
Large clumps that block the filter inlet sound pretty scary, and surely indicate that the tank is not clean, and the fuel needs polishing too.

MV Wanderlust 07-24-2018 08:45 AM

To your original question, "What is it?" From your description, it sounds like it's a clump of algae. Diesel fuel tanks, especially those that aren't kept topped up and/or have been sitting unused for a while, can form condensation in them. That water provides a breeding ground for algae. The tiny critters are bad enough but their excrement can settle like sludge on the bottom and sides of the tank, often getting sucked into the fuel lines and clogging the fuel lines and primary and secondary filters. Pretty common, actually. Happened to us, too, when we bought our boat and started to move it home. Completely shut down our starboard engine.

Probably your best solution is to run the tanks down to a minimum level and then have a tank cleaning and fuel polishing done. (They charge by the gallon so might as well have them do it when your tank is nearly empty.)

Heron 07-24-2018 12:28 PM

While I can't see your pic, it might very well be ASPHALTINE. An unfortunate side benefit of old diesel fuel. Check out my thread on this when I discovered the problem. Lots of pics and progressive filter solutions to avoid those surprise shut-downs..:

sdowney717 07-24-2018 12:31 PM

I have been wondering, why dont they seal the tanks from the humid air?
For Gasoline, they use a VOPR system, vapor over pressure relief, it lets tank vent above 1 psi, and lets air in when motors draws fuel, but most of the time, the tank is not being used, so it will be sealed from outside air. It has made a huge difference on my gas powered boat using the VOPR type cap.

Here is a vpr valve goes into the 5/8 vent line then exits the hull.
This would be used with a vented fuel fill
BK0280025 - Diurnal Control Valve (DCV) 5/8" x 5/8" - Vapor Space Management - OE Boat Builders

Comodave 07-24-2018 03:03 PM

I donít know if the majority of water in the tanks come from the vents or rather in leaking O rings on the fuel filler. Good thing to check and see if they are in good condition or not.

FF 07-24-2018 04:10 PM

Water is part of even "clean" fuel fresh from the distributor.

The chance exists that the marina might change their filters often enough does exist.

Good luck ,the commercial fuel docks do a better job than marinas.

A Baja filter should catch heavy water coming in with the fuel , but is a PIA as it slows down the fueling.

The only real good solution to water in the fuel is a sump that can be pumped easily.

Fletcher500 07-24-2018 05:52 PM

John Easly, do you have some data from an engine manufacturer or other reputable source that condensation and subsequent water accumulation in the fuel tanks occurs (enough to cause issues) if tanks are not kept full? I am not talking about years, just a season for example. I previously thought the same thing, but after some digging, including on TF, found it to be mostly anecdotal wives tails. It has been discussed in detail many times, so no need to create a 10page string, but just wondering if you have some data to support your statement?

boatpoker 07-24-2018 10:56 PM

Algae simply cannot exist in the presence of diesel.
There are certain bacteria that can.

sdowney717 07-25-2018 06:29 AM

Racor says water comes from condensation inside tanks.


Water is commonly found in diesel fuel due to condensation, handling and environmental conditions.

Diesel fuel tanks are always subject to water condensation because diesel fuel, unlike gasoline, has no vapor pressure to displace air. When a fuel tank is warm, the air expands and is forced out. As the tank cools at night, humid air is sucked back into the tank and water condenses out on the cooler tank walls. (One reason to keep diesel fuel tanks topped off if possible.)

For ethanol gasoline, does not require visible water in fuel for acetobacter to grow.
In the fuel are micro droplets of water, the bacteria live at the interface of the water and fuel layers within the droplets scattered throughout the fuel.

That water is easily absorbed from the air right into the fuel. It is easy to demonstrate, on a warm humid day, put gas in a clear jar, in a few minutes it turns cloudy from absorbing water.

Diesel and water don't mix the same way since no ethanol is present, but the humid air is still getting into the tanks by the large open vent line with a continual constant exposure. Fuel expands and contracts with temp change, so the tank is breathing. The bacteria will grow at the interface of water and diesel.

Conall63 07-25-2018 06:48 AM

Looks like a wad of crud.


Autoteacher 07-30-2018 01:59 PM

High Wire 07-30-2018 02:06 PM


Originally Posted by Autoteacher (Post 685203)

Google wants me to sign in.:banghead:

halfmoon 07-30-2018 07:46 PM

Biobor crud
Polished x 3, still had engine failure from clogged fuel line. Emptied tank, found large clear crystals, some size of small fingernail! Dissolved in water, not acetone. Added 30 gallons water to tank, let it rock at dock overnight and then pumped it out. Wiped tank dry, fueled and no more crystals. They were large enough to block the uptake line. Boat had been on lift maybe four years. Last polisher got some smaller crystals, saved them for me, remarked that he had never seen anything like them.

boatpoker 07-30-2018 08:05 PM

Sounds like salt crystals from urine .... sure you got the right tank :)

halfmoon 07-30-2018 08:43 PM

Correct tank?
I'm sure my Albin 28 did not have a 120 gallon holding tank. AND my olfactory sensitivity assured me that the tank held diesel fuel.

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