Fuel issues

Hi.
We have been having some issues with our fuel.
We have 2 x 600 litre tanks that were full of bug and water.
I built a mobile fuel cleaning unit out of 1 x 100 micron element and 1x 10 micron racor plus a 1 x 2 micron filter.
Filtered the fuel into another container removing 15 litres of water.
The first Racor inline removed 99.9% of the water the 2nd the rest.
We accessed the tanks from their large inspection plates and used wet vac to remove the rest of the bug, water etc.
Tanks ended up very clean.
An Algaecide was added to the fuel before pumping it back to the tanks.
Thought we had done a great job.
Until after adding another 800 litres and 15 hours running our filters were full of water again restricting flow worse than before.
Removed about 5 litres in under 2 hours running.
Now scratching our heads trying to work out where the water came from.
Bad fuel supply? Don't thinks so, our other boat is fine.
Did some of the water get past our fuel filter ?
By adding the fuel conditioner does that release the water from the fuel?

Any ideas

Thanks
Rob

Here is a photo of the fuel in one of our filters.
Doe not look right.

Trying to remove a high % of water from fuel, with a lot of suspension of the water, is not trivial. Don't depend on micron filtration.
That's the job of a centrifuge.
http://stevedmarineconsulting.com/wp-content/uploads/2014/03/CentrifugeFilters115_05.pdf

Is this low sulfur diesel you are working with?

You might try this product to test for water: http://fleetfueltesting.com/buy-diesel-fuel-tests/test-for-water-in-diesel-fuel

Thanks Diver Dave.
Yes it is low sulphur Fuel.
I will read the articles now.
Regards
ROB

Did you let the fuel you pumped out settle for at least over night and sample it before putting it back into the tanks?

Did it rain after you put in the new fuel?

Hi Capt Bill

No i didn't let it settle overnight .
Put it straight back in.
Thought the 2 racors would of got the water out.

Thanks
Rob

looks like its settled pretty good now. I would simply disconnect the output of the racor and run a rubber fuel line back to the fill of the tank and recirculate the fuel thru the racor back to the tank while baby sitting the racor and draining the water as needed. Might take an afternoon but it will get enough of the water out to regain control of it. You may need to buy a 12v fuel pump at a autoparts store if you use a mechanical lift pump.

I had to do this very thing in order to clean my diesel up before I transferred it to 50 gallon drums so I could cut out my tanks. its easy enough to do, you just have to watch the racor and drain it before theres too much water in it. Also shut off the pump when you drain the water or it will just suck air thru the drain.

Be sure to check the top of the tanks for rust. Mine was so bad that when I cut the fill hose the metal fitting just fell in.

this is 2 - 350 gallon tanks, and weeks of misery cutting them up.

Bluetide said:

Hi Capt Bill

No i didn't let it settle overnight .
Put it straight back in.
Thought the 2 racors would of got the water out.

Thanks
Rob

Click to expand...

Oops!

you didnt answer the rain question. leaking inlet seals are often a problem

What was the flow rate of your polishing pump? Water will go through the filter media under enough pressure or vacuum. Also, too much flow can blend the fuel and water which will go through the filter only to separate later in your tank.

Ted

So, your fuel tanks were drained, vacuumed dry and inspected. Now you are still getting water in your Racor. So NEW water is getting in somehow. Here are some culprits:

1. Filler cap is leaking- bad o-ring.
2. Tank vent is letting water in, maybe due to broken plastic fitting.
3. If you have a Cummins 6BTA engine or another make with a fuel cooler, then it is leaking.
4. Filler fitting is not sealed well to deck letting rain water run down filler hose and then getting into tank due to bad hose to tank seal- long shot.

David

Hi Bayview
No rain and no water anywhere near the fuel inlets or vents.
Cheers
Rob

Hi OC Diver
Yes my pump i used to suck fuel through the filters had a much higher rated volume than the racors.
I think this may of happend.
Cheers
Rob

Often when you open tanks, much of the interior is occluded by baffles. So you really can't see all the interior. In that case, you do the best you can and some water/junk does make it back to the filters.

I think i know what why i have so much water in the tanks.
I have used a fuel conditioner (demulsifyer) that has dropped all water into free water.
Filtered the fuel yesterday(600litres) and removed 20 litres of water.
This is after filtering the fuel 2 weeks earlier and removing 15 litres and then adding the fuel conditioner.
Found an article that was very helpful.
Technical Bulletin:Update Water Elimination in Diesel Fuel

Rob

Does your engine have a fuel cooler?

Ski in NC said:

Does your engine have a fuel cooler?

Click to expand...

Hi Ski

No fuel cooler.
Thanks for that.
Rob

Ski in NC said:

Does your engine have a fuel cooler?

Click to expand...

Hi Ski

As it turns out i have got a fuel cooler.
I was told that i didn't.
So that is my problem 100%.
It happened again with a new batch of fuel 1200 litres.
Would you know the part number by any chance and where to purchase?
Regards
Rob

Probably can't help with part numbers, especially since I don't think you posted what type of engine you have.

In many cases the fuel cooler is unnecessary and can be eliminated. Depends on engine, how hard you run, and size of the tanks.

Ski in NC said:

Probably can't help with part numbers, especially since I don't think you posted what type of engine you have.

In many cases the fuel cooler is unnecessary and can be eliminated. Depends on engine, how hard you run, and size of the tanks.

Click to expand...

Thanks Ski
Got the part numbers.
Hard to find here in Australia.

Will keep the coolers due to the fact i will need the horsepower and have reasonably small tanks(600 litres x 2).
This boat works 8 hours a day.

Rob

Bluetide said:

........
This boat works 8 hours a day.

Rob

Click to expand...

Wow, that's highly unusual. I'd bet you had a bad supplier.

Seevee said:

Wow, that's highly unusual. I'd bet you had a bad supplier.

Click to expand...

We had fuel delivered from another supplier after the first time.
Then it happened again so we can rule that out.
Will be down at boat tomorrow to test and remove coolers.
Rob

Is it a CRD diesel? Or super high tech injection? I would be surprised a raw water fuel cooler would be value add in a mechanical system as it wouldn't change pulse width for density/temp anyway.

kev_rm said:

Is it a CRD diesel? Or super high tech injection? I would be surprised a raw water fuel cooler would be value add in a mechanical system as it wouldn't change pulse width for density/temp anyway.

Click to expand...

Hi Kev

Engines are Cummins 6bta 315.

Update.

Removed both fuel coolers(twin engines).
Both failed.
Would be looking for a different design i would think.
Anyone with these coolers if you havn't already done so should maybe inspect/test and replace.
Rob

Look at your fuel system, make sure that there is no way for the return flow to the tank to be blocked. If that flow is blocked, pressure in cooler can go sky-high and collapse it internally. A simple valve misposition can do it, or if a non-return fitting is accidentally used in the return path.

What do insides of fuel cooler look like? Any deformation? Usually the Cummins coolers are pretty reliable, although there have been occasional failures.

If both failed, chances of both being a random failure seem low. Worthwhile to look for a common cause.

Ski in NC said:

Look at your fuel system, make sure that there is no way for the return flow to the tank to be blocked. If that flow is blocked, pressure in cooler can go sky-high and collapse it internally. A simple valve misposition can do it, or if a non-return fitting is accidentally used in the return path.

What do insides of fuel cooler look like? Any deformation? Usually the Cummins coolers are pretty reliable, although there have been occasional failures.

If both failed, chances of both being a random failure seem low. Worthwhile to look for a common cause.

Click to expand...

Hi Ski
Thanks again for your great info.
Will run the return lines into a bucket tomorrow to see if we have good flow.
I have gone out and bought a different heat exchanger a Bowman 31 982, this is a tube bundle type. I was a bit concerned that this would not give the correct flow but the guy at the shop gauranteed it would.
Will test tomorrow.
Raw water is delivered by Jets and there was no visable signs of damage to the insides of the coolers.
Rob

Not concerned about return flow from engine as would be determined by bucket test, concerned about whether flow from engine could be blocked on its way to tank. More of a plumbing issue than engine issue.

Usually if this happens, cooler fuel passage inside tube collapses, which is visually obvious. So not likely your issue.

Please excuse me for the thread hijack but what is the purpose of a fuel cooler? (ok the name says all, to cool the fuel of course). I mean I thought it was better for diesel fuel to be warm as more fluid and better for injector "mist".
Ski may you give me some light on this and decrease my ignorance

L.

Lou,
Many turbo engines that are expected to run hard and long times use a fuel cooler. When fuel transits the injection pump, and injectors it picks up heat. That heat will expand the fuel to the point that the engine gets a sufficiently less dense fuel charge that the engine cannot make its rated HP. The fuel coolers take that heat away.
Often takes the fuel to reach approx. 140F to be a problem but it can happen on engines working hard or long enough and with tanks not large enough to dissipate that heat readily.
My own engine, a natural, heats the fuel. The return lines are darn warm and at the end of a day's run the whole tank is noticeably warmer.