Fuel Contamination

Hello all,
First outing of the season this past weekend and had a fuel contamination issue. Fuel tanks were topped off before a final 6.5 hour trip to home port last Fall. No issues on trip home and clear bowl for winterization. I topped off tanks again before storing boat inside for the Winter using 5 gallon diesel jugs purchased at a filling station, about 20 gallons total. This is where I suspect I got my bad fuel.

I ended up draining over a gallon of water(?) so far from Racor bowl while underway on a 2.5 hour trip. This is a first for me and bit disconcerting. I feel I was lucky to have discovered it before we had a big problem. At one point I saw no red fuel in the bowl. It raises a handful of questions.

1. What would/could have happened if this went undiscovered? I figure the engine would start running rough before shutting down giving me an opportunity to investigate. Worse case?

2. Now what? I need to know the water (or what else could it be?) is all out before setting out again with peace of mind. Is a fuel polishing advised/required? If so, (please excuse my ignorance on this), is that typically a mobil service that comes to your marina? What about running the engine and gen-set in the slip until I don’t have to drain the filters any longer? If the boat sits, won’t the water settle to the bottom and be unreachable by the fuel pick up? Next time we’re out the water sloshes around, mixes with the fuel and we have the same issue.

We’ve had the boat, 78 Mainship Mk1 for about three years. Two original 110 gal. aluminum tanks. I know clean fuel is critical and I have been changing filters, adding algae treatment and watching the bowl but that’s it. I’m still learning and would appreciate any thoughts and advice.

Thank you so much in advance,
Steve

Is there a drain on your fuel tanks? If so use that until no water. Your fuel pick up will not reach to the bottom of the tank. So using engines to polish your fuel is not a complete solution. Algae will grow at the water fuel interface.

Also replace your fuel fill O rings just in case the water got in that way.

Almost no tanks draw the fuel from the very bottom of the tank. So if you're getting water in your Racor then you have even more water in your fuel tank. The only way to be sure its all out is to drain (or draw) from the lowest point of the tank. Frankly its unlikely (but still slightly possible) that your water came from the service station. The o-rings on the filler caps are a definite possibility and should be replaced regularly.


Ken

Ditto the fuel filler O rings. One other question, and not unheard of - a diesel fuel thief who did not screw fill caps back on tight. Were your tanks full when you splashed the boat?

Thank you for replying everyone.
Unfortunately I have no tank drains. No fuel thief, as tanks were still full at commissioning. The filler neck is not flush to deck but that is a possible source. The black paper gaskets in the screw on cap are old. Kind of like thin tar paper. I’ve had no luck finding replacements. Ideas about substitutes?
Also, any thoughts on proceeding from here? Keep running and draining?
Try getting fuel polished? What could happen if water gets by the filter/separator?
Aside; Is fuel polishing a general maintenance item or as needed item?
Again, many thanks,
Steve

Considering the apparent volume of water, it is very hard to believe that it originated with just 20 gallons of gas station diesel. Also, generally, I would expect gas stations to have better quality fuel than marinas because of being away from water and faster turnover. So, I would start trying to figure how so much water got into the tank(s) before trying to clean it out. Otherwise, it may just re-occur.

Paper gaskets? Might describe or post a picture of fuel fills. If deck fills are flush, rubber O rings are normally used.

SKS said:

The black paper gaskets in the screw on cap are old. Kind of like thin tar paper. I’ve had no luck finding replacements. Ideas about substitutes?
Steve

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Thin black gaskets? Maybe a piece of inner tube rubber would replace these?
If your caps screw on, how about a lithium grease on the threads? Would also act as a water repellent.

SKS said:

Thank you for replying everyone.
Unfortunately I have no tank drains. No fuel thief, as tanks were still full at commissioning. The filler neck is not flush to deck but that is a possible source. The black paper gaskets in the screw on cap are old. Kind of like thin tar paper. I’ve had no luck finding replacements. Ideas about substitutes?
Also, any thoughts on proceeding from here? Keep running and draining?
Try getting fuel polished? What could happen if water gets by the filter/separator?
Aside; Is fuel polishing a general maintenance item or as needed item?
Again, many thanks,
Steve

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Paper gaskets sounds extremely suspicious. I've seen a lot of fill caps but nothing so poor as a paper gasket. Could you post a picture of the filler open with the cap next to it?


You can keep running and draining when you see water, but you'll never get all the water out of your tanks that way and water in the tanks causes other problems too, such as corrosion of the tank and allowing bacteria and/or fungi to grow in it. The growth will also start to clog your fuel system.


Polishing generally won't get the water out of your tanks either unless you can somehow draw from the very bottom. The only way to get all the water out of the tank is to draw from the lowest point. If you can't do that via a plumbed opening, then you have to open the top of the tank and suck it out.



Ken

O-rings are what I have on my flush-mounted deck fuel fills. Had old vinyl caps long ago and one failed causing contamination. It was an expensive lesson on professional fuel polishing and tank scrubbing.

O-rings=cheap

Failed O-rings=expensive.

I think you have found your problem. Paper gaskets are not the right part. I use PERKO o-rings for deck fills because they are rated for fuel/oil. O-rings not rated for fuel/oil can decompose. As to how to go forward, I would have the fuel professional polished before organisms can grow. Treat with biocide religiously. Maybe start with a shock treatment.

FWIW, my o-rings when I bought the boat were squished as thin as paper. They had not failed but I replaced promptly. Now I replace once per year. Why not? Only a couple bucks.

kchace said:

Polishing generally won't get the water out of your tanks either unless you can somehow draw from the very bottom. The only way to get all the water out of the tank is to draw from the lowest point. If you can't do that via a plumbed opening, then you have to open the top of the tank and suck it out.

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I would agree that I doubt you could have gotten that much water in your tanks from bad fuel (although anything is possible I suppose). My first thought is a leak through the fill port of the tank.


My first thought was the same as Ken's suggestion. Try to pump/siphon out the water from the bottom of the tank. This could be hard depending on your access to the tank. If you can get access to the top of the tank, remove the fill tube and run a small rigid pipe to the bottom of the tank and pump fuel into a bucket until you don't get any more water. If you can't get access to the top of the tank, you will need to try and run a small diameter hose through the deck fill and see if you can get it to the bottom.



Pumping the fuel into a large glass container will allow you see see if you have water or not. Keep emptying that container into a waste fuel can and repeat until no more water.


Sorry and good luck.

Like the OP said, the mainships' deck fill are not flush, they used a deck fill with a nipple extending about 2" above the side deck. The are awful for stubbing your toes but great at protecting the fuel tanks from water contamination, I doubt the worn paper gasket is the problem unless, somehow you had 2 inches of standing water on your side deck this winter.
Without access to bottom of the tank, I think your best alternative would be removing the fill hose at the top of each tank and trying to snake a smaller hose to the lowest corner of the tank and pumping out any water in the tank. This may be difficult due to baffles but if you can reach any corner, you may be able to ballast the boat to make that the lowest corner. Good luck.

I would get a diesel pump and plumb it to your Racor outlet. Make sure pump is rated for continuous duty. Take some fuel out of one tank, ballast the boat to list a little, undo the fill opening hose and stick a soft copper pipe clamped to fuel hose. Clamp another hose to the outlet of the pump.

Place the copper pipe wand down the fill opening and adjust it so it reaches the lowest point in the tank. Place the outlet hose into the same hole to return the clean fuel to the tank. The pump will suck the fuel/water out of the low point, through the Racor and clean fuel back into the tank.

You will have to run this for a while, hours, days depending on severity, since the clean returning fuel is commingled with the bad fuel. It would be a good idea to have a large supply or Racor elements, preferably 10 to 20 microns since you will be pumping out yutz from the bottom of the tank.

Ideally, you would pump all the fuel into 55 gallon barrels instead of the same tank as described above and return the clean fuel back into the tank after the tank was clean.

You could also cut a large inspection port on the tank top and install the inspection plate kits sold for such circumstances. And do a better inspection and cleaning.

Or hire a professional fuel polishing company. They will install the inspection plates, pump fuel into parallels and return clean fuel to the clean engins as above but costing $$$$

But solve the leak first. You can plug all the ports on the tank except the fill and one small port which you install an air connector. Pump low pressure into the tank through air connector, 5 - 10 psi and liquid soap around the inlet cap You will see bubbles if the fill cap seal is the culprit.

Have you pissed off any dock neighbors lately? With the raised filler tube rainwater doesn’t seem likely. But having that much water doesn’t seem like a leak into the tank. Maybe someone is filling your tank for you but with a water hose...

You have a question mark after the word water in your description, are you uncertain that it was water in the racor? Diesel from the gas station is not red like off road diesel. Any possibility you had clear diesel from the gas station in the bowl rather than water? Water in the fuel, if it reaches the injector pump would likely cause the pump to fail.

If you are not sure if the stuff in your tank is water, test it with KolorKCut water finding paste. Smear some on a thin wood stick and stick it down the tanks fill hole. If the yellow turn red - you got water. If you wanted to find how deep the water is, smear it along the whole stick and it will turn red as high as the water reaches.

It's not expensive, $10 on Amazon. One tube has lasted me over 30 years and I test the tanks for water every month during the winter months. During the cruising season, I test for water when I dip the tanks to calibrate the site gauges every couple weeks.

Tomas said:

You have a question mark after the word water in your description, are you uncertain that it was water in the racor? Diesel from the gas station is not red like off road diesel. Any possibility you had clear diesel from the gas station in the bowl rather than water? Water in the fuel, if it reaches the injector pump would likely cause the pump to fail.

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Or blow an injector tip. Pretty unlikely unless the water in the Racor got high enough up in the housing to reach the fuel exit.

Tomas said:

You have a question mark after the word water in your description, are you uncertain that it was water in the racor? Diesel from the gas station is not red like off road diesel. Any possibility you had clear diesel from the gas station in the bowl rather than water? Water in the fuel, if it reaches the injector pump would likely cause the pump to fail.

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This might be it. OP mention service station diesel. Bet this is what happened.

Wouldn't the service station diesel just mix with the off-road red diesel and lighten the tint. I can't imagine it would completely separate and show up as clear in your filter?? I am wondering is there is any way you could have gotten confused when filling your water tank and put the water hose in the fuel fill? It is not that difficult to do......


The curious thing is that your engine is still running with that much water in the tanks and filter.....

Tomas said:

You have a question mark after the word water in your description, are you uncertain that it was water in the racor? Diesel from the gas station is not red like off road diesel. Any possibility you had clear diesel from the gas station in the bowl rather than water? Water in the fuel, if it reaches the injector pump would likely cause the pump to fail.

Click to expand...

Very good catch Tomas.

If there is any doubt that it could be water then place a small amount in a zip lock bag and put it in the freezer.
In almost every install that I have seen the fuel pickup is 3/4+ inches above the bottom of the tank so you will never get it all without reaching the bottom.
We had taken about 5 gallons of water out of a tank after buying a boat that had a poor "O" ring seal on a fuel fill.
It was fairly easy to get access to the tank through the fuel gage hole by removing the gage.
Then used a 'vane puppy' oil/fuel transfer pump with a length of soft copper tubing large diameter ice maker line with a short length of rubber hose at the end.
By moving and bending the copper line we were able to get to most all of the tank bottom and pump out the water/fuel into 5 gallon pails and by letting it decant for a bit before pouring off the fuel and leaving mostly all water.\
We have used the vane puppy pump for oil changes and fuel issues ever since - about 15 years back.
I am sure there are equally good options to the Jabsco vane puppy pump as well.

You guys are awesome! Thank you for all the replies.

If my photos uploaded the gasket and filler neck are shown
I replaced very old and brittle material with fabricated rubber like material for now. Thank you Koliver!
Not sure what the groove in the threaded neck is for. Any thoughts?

I am not ruling anything out and it doesn’t really matter. The water has to come out. I like the pump out thoughts. Question for smitty477, why a short length of rubber tube at the end of the copper tube?
I will do what I can about filler neck intrusion but may never know for sure.
The non dyed gas station diesel I believe would mix with the marine diesel and not be settling in the fuel separator. Perhaps I’m incorrect. What else would separate out in the bottom of the Racor bowl but water?
I am going to get the KolorKCut paste to confirm a few things. Thank you
Syjos!
No water hose in the tank mistake but sabotage? Vandalism very remote possibility but I have not pissed off anybody at the marina.
It’s odd that this is an “all of a sudden” issue. I am leaning towards the bad filling station diesel theory since I have never had to drain a drop of water out in three years and 200+ hours. If water was getting in at the filler necks this would have shown up earlier I believe and not so excessively. Over a gallon drained out in ~ 2.5 run time seems like a sudden dump of water from somewhere?
Thank you again!

The groove allows a chain to be attached to the cap, and yet not interfere with refueling nozzles.

SKS said:

You guys are awesome! Thank you for all the replies.

If my photos uploaded the gasket and filler neck are shown
I replaced very old and brittle material with fabricated rubber like material for now. Thank you Koliver!
Not sure what the groove in the threaded neck is for. Any thoughts?

I am not ruling anything out and it doesn’t really matter. The water has to come out. I like the pump out thoughts. Question for smitty477, why a short length of rubber tube at the end of the copper tube?
I will do what I can about filler neck intrusion but may never know for sure.
The non dyed gas station diesel I believe would mix with the marine diesel and not be settling in the fuel separator. Perhaps I’m incorrect. What else would separate out in the bottom of the Racor bowl but water?
I am going to get the KolorKCut paste to confirm a few things. Thank you
Syjos!
No water hose in the tank mistake but sabotage? Vandalism very remote possibility but I have not pissed off anybody at the marina.
It’s odd that this is an “all of a sudden” issue. I am leaning towards the bad filling station diesel theory since I have never had to drain a drop of water out in three years and 200+ hours. If water was getting in at the filler necks this would have shown up earlier I believe and not so excessively. Over a gallon drained out in ~ 2.5 run time seems like a sudden dump of water from somewhere?
Thank you again!

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"Question for smitty477, why a short length of rubber tube at the end of the copper tube?"
Soft copper 'rubbed' off on an aluminum tank bottom could (might) promote corrosion in the presence of water.

FlyWright said:

The groove allows a chain to be attached to the cap, and yet not interfere with refueling nozzles.

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What should prevent water intrusion through that slot?

dhays said:

What should prevent water intrusion through that slot?

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I would immediately (if not sooner) seal up that slot!

Thanks smitty477.
I got a gentleman’s B in chemistry.

koliver, seal up with what?

SKS said:

Thanks smitty477.
I got a gentleman’s B in chemistry.

koliver, seal up with what?

Click to expand...

JB Weld or similar epoxy