Hazy Diesel Fuel

[harpon]

After refuelling the fuel tank with 500lts of diesel, I noticed that the fuel in the primary fuel filter bowl became hazy(see photo). I continued to run the engine for our trip and monitored for any signs of water in the bowl but there were none. We continued our journey of about 8hrs running the engine as there was no wind.
We reached our destination without any issues. Left the boat a few days later and got a mechanic to look at the fuel a few weeks later hoping that whatever was in the fuel it would have settled down, but that was not the case, fuel still hazy.
I subsequently found that prior to refuelling the boat, the feed line of the dock fuel filling pump was changed as well as some filters from the in ground tank to the fuel filling pump. The marina manager assured me that the people that did the maintenance had tested the quality of fuel and it was fine. No other boats after mine had any issues.
Would appreciate any thoughts on the issue as we are all at a loss as to what is causing the hazy fuel.
Thanks

[Bill O]

Doesn't look great.

Did you take a jar and do a small pull from the marina fuel? Does it look clear?

If it was clear, maybe you have water/contamination in your tank that was stirred up during the recent addition of fuel or the trip.

[Compass790]

I have used some old fuel that had gone hazy & it caused no problems.
But I have a mechanical indirect injection engine. If you have the right filtration & water seperation as it appears you do I'd imagine it would be ok. I'd be slightly nervous if its a common rail engine but if you have a 2 micron final filter you should be ok.
I'd have a few spare filters but if you ran problem free for 8 hrs it sounds promising.

[Jim Cate]

sending your own sample to a lab for analysis would ease your mind. Not terribly expensive, I believe, and would give you an unbiased opinion of quality.

Jim

[tkeithlu]

Here are some home test swabs.

https://www.jmesales.com/vp-racing-f...QaArHyEALw_wcB

It does sound odd. Water would be expected to settle out. Micro organisms would make it smell bad. Whatever it is, it doesn't appear to be interfering with your engine operation.

[Bill O]

Originally Posted by tkeithlu

Water would be expected to settle out. Micro organisms would make it smell bad. Whatever it is, it doesn't appear to be interfering with your engine operation.

Agree that water should settle out unless the fuel had chemical additives to help suspend small amounts of water in the fuel.

While it may not appear to interfere w/engine operation, water in the fuel can reduce performance (slightly less fuel when replaced by water) and possibly injector tip erosion (if too much water).

To the OP, did the mechanic or yourself check for water at the bottom of your tank? I like to periodically pump out the bottom layer of the tank to check the "health" of the tank.

[team karst]

Its called "suspended water" to turn diesel cloudy. Water is attached to the hydrocarbons. "free water" falls to the bottom in diesel. "emulsified water" is enough to turn diesel milky.

[thinwater]

Out side of a lab it is impossible to be certain (I ran petroleum labs for many years), but given you explanation, it is probably finely emulsified water, just a few hundred ppm. Possibly some very fine solids as well, which help stabilize the emulsion (sub-micron--too fine to filter out)



Not likely wax. Too warm. Not likely bugs or all the fuel would look like that.



You might try testing an additive, like Startron, which is known to encourage a clean break (test in a 1-liter glass jar), allowing the filter to remove it. Might work, has for me in the past.



But probably harmless. Treat with Biobor JF, because if there are any bugs in the tank, the emulsified water will encourage growth.

[team karst]

FOI test tube kits claim sub 500ppm sensitivity to water. Search u tube for detail.
I have not tried the kit.