Revisiting Erroneous “Water in Fuel” Alert

[Wee Venture]

I know this topic has appeared in previous threads but I don’t remember seeing a consensus on what is actually causing the erroneous “water in fuel” alerts. I have seen advice to replace the sensor and/or to replace the secondary fuel filter, which has apparently worked in some cases but is an irritating annoyance/expense and doesn’t address the cause.

Here is my experience: we have an R-31 which we bought new a little over two years ago, have put over 500 hours on the engine (Volvo Penta D4 300HP), have taken it to the top of the inside passage in Alaska fueling at small out-of-the-way fuel docks (some served by barged-in fuel), and never had a “water in fuel” alarm or a hint of water in all visual fuel inspections. During all of this time, I had not been using fuel additives.

About three weeks ago, I filled up the tank with diesel because I want to keep it full for the winter months. Also, for the first time, I decided to add two fuel additives because the fuel in the tank will be sitting unused for some months and because some have said this is always best practice. Just before filling up, I added Biobor JF and Starbrite StarTron Enzyme Fuel Treatment, in the recommended doses for the entire 180 gallon capacity of the tank. The fuel itself came from a very reputable, very busy fuel dock (Morrison’s North Star Marine on Lake Union in Seattle). I have fueled here before a number of times without incident. I have also asked in the past whether they add any fuel additive to their fuel and they say they do not.

Within minutes after leaving the fuel dock, I began getting recurring “water in fuel” alerts on my engine display. After dismissing an alert, all would seem fine for awhile and then it would pop up again. I was extremely skeptical that this alarm was triggered by actual water, but I did my due diligence and unscrewed the sensor from the secondary fuel filter and let fuel run into a clear ziplock bag. Sure enough, it was pristine, not a drop of water.

So this is not a controlled scientific study but the circumstantial evidence seems overwhelming to me that the alarms are being triggered by one or both of the additives - or maybe the interaction of the two together. The sensors that trigger the alarm apparently work by measuring the difference in electrical conductivity between diesel fuel and water. Maybe one of the additives changes the conductivity enough to trigger the alarm?

There could be other reasons for false alarms in other people’s experience, of course, but in this case it seems like the additives are the only reasonable conclusion. I would be interested in other people’s thoughts and to know if anyone else has experienced a similar problem with either or both of these additives.

John

 

[Red Raven]

Hi John,

I suspect you right that it is triggered by one of the additives or the combination. Just be sure it is not water, however, did you drain off and capture some fuel from the primary fuel filter as well? The sensor on the secondary is very sensitive and there may not be enough water for you to see it. If there is any water in the fuel it seems to me it is more likely to collect in the bottom of the primary first so you may want to drain that one a bit and see you still get the error.

I have only seen this alarm on our boat once 3 years ago and after draining a bit from the secondary filter it did not come back on. I have no clue why it came on. I don’t recall adding an additive at that time. I have used Biobor in the off season since and have never had an alarm. I have never used the Starbrite product you mention.

It will be interesting to see what other’s experience has been.

Curt

 

[ixlr8]

We have ValvTec diesel fuel here at some marina's. It has additives in it and I have had folks comment that when they use it they get 'water in fuel' alarms, so they avoid ValvTec fuels. Other folks say they haven't had any issues with it??!! Not sure who was running what for engines, maybe Volvo's are more sensitive.

 

[Navigator's Son]

Interesting - I didn't think it might be the actual fuel itself.

I had the "Water in Fuel" alarms last January. I too took the time to drain the fuel filter. Absolutely no water at all. I think I got the alarm 3 times. I drained the fuel filter twice. On the third time I simply ignored it.

Haven't had the false alarm ever since...

 

[dclagett]

I had water in fuel alarm for the first 2 years I owned the boat every few hours of operation. Never any water in fuel drained from the engine mounted fuel filter where the water in fuel sensor is located. I did get some water when I drained the external fuel filter last year when we had significant rains throughout the year. I found out that the fuel vent that is mounted on the transom, which has a slight angle, allows some water to be ingested into the vent in heavy rains. It looks to me that the fuel vent is made for a vertical surface not a surface that has a slight angle towards horizontal. So I put a clam shell cover over the fuel vent which fixed the problem. I also cleaned the tank which only had a few ounces of water.

This season started out with the same problem, water in fuel false alarms. No water in either filter. I also let the sample of fuel taken from each filter sit for a couple weeks and no water was found to be present. I then took off the connector attached to the water in fuel sensor and sprayed it with CRC and reconnected it. For the last 80 hours this season I have not had a water in-fuel alarm. Maybe it is now fixed since I would get an alarm at least every 6 hours. Only time will tell.

 

[Wee Venture]

Finally got around to trying Curt’s suggestion to drain some fuel from the primary fuel filter to look for any trace of water, in case that was what was triggering the alarm on the secondary filter. I was waiting till a spigot that I ordered to replace the plug in the bottom of the bowl arrived so I could swap it out in one operation.

This is a digression but I highly recommend adding a spigot to your primary fuel filter if you don’t already have one. It makes it much easier to check for water and contaminants in the future. And to keep your bilge clean in the process.

Here is a link to the one I purchased, which fit perfectly and works well:
https://www.amazon.com/Racor-19492-U-L- ... B000N9JHX4

So after draining some fuel, I found no trace of visible water - either in the primary or secondary filter. So the evidence seems overwhelming that the “water in fuel” alerts are being triggered by one or both additives. One of the products is an emulsifier which is supposed to encapsulate microscopic droplets of water so that they can pass through with the atomized fuel and not damage the engine. I don’t know if these suspended droplets could change the conductivity enough to trigger the alarm; or if perhaps the additives themselves have a higher conductivity.

At any rate, I will need to think about the cost to benefit ratio of using additives in the future.

 

[BB marine]

So after draining some fuel, I found no trace of visible water - either in the primary or secondary filter. So the evidence seems overwhelming that the “water in fuel” alerts are being triggered by one or both additives. One of the products is an emulsifier which is supposed to encapsulate microscopic droplets of water so that they can pass through with the atomized fuel and not damage the engine. I don’t know if these suspended droplets could change the conductivity enough to trigger the alarm; or if perhaps the additives themselves have a higher conductivity.

Common rail injectors need lubrication to reduce wear, lower sulfur fuels have reduces lubricity. This is one advantage of using a additive, using an additive may help add lubricity to the fuel. Emulsifiers in fuel conditioners combined diesel fuel and water together. The microscopic water droplets can reduce lubricity. Alcohol and emulsifiers when used with a water separating filtering system are not needed or recommended. Actually a demulsifier additive would be better to help the water droplets to separate so the fuel filtration system can do its job more effectively, avoiding any moisture from passing through the injector pump and injectors possibly damaging them.

John, I don't know how much emulsifiers do or don't contribute to, or possibly cause the emulsified water/diesel to damage pressure pumps and injectors. When I researched which additive to use or which additive would be best for my use. I came to the conclusion that a demulsifier or a product with neither emulsifier or demulsifier would be the better option.( My opinion) I would rather use the Racor and Volvo filter to do the job, separate the water from the fuel. I do agree with you that the additive could have been the cause of the "Water in Fuel" Alarm.

 

[Wee Venture]

Brian, thanks for weighing in on this.

Here is my dilemma. We all know that water is bad for diesel fuel and diesel engines. Especially common rail engines, where the fuel is under tremendous pressure as it hits the injectors. We also know that one way or another, eventually, at least a minimal amount of water will make its way into our fuel, even if in microscopic quantities. So what do we do about that? I am aware of three options:

1. Do nothing, at least by way of additives, and count on the water separating filters to strip the water from the fuel, allowing it to collect in the sediment bowls. This is fairly effective but my understanding is that, while the filters take care of free water, there is also naturally occurring emulsified water that can make it through the filters all the way to the injectors and combustion chamber. If we have been underway, especially in rough seas, and there is a layer of water in the bottom of our tank, the agitation will create an increased concentration of smaller droplets of emulsified water in the fuel itself. If this emulsified water gets to the engine, which it is likely to do, it is damaging over time. I suppose an additive for lubricity might help to slow the damage though I’m not certain how effective that would be in mitigating water damage.

2. Use a demulsifier additive. The idea here is that the additive would break down the film surrounding the droplets, allowing them to coalesce into free water. The free water would then be caught by the fuel/water separators and only pure fuel that has been demulsified would make its way to the engine. But the problem with that as I see it is that the additives are introduced into the fuel tank itself, so the phase separation actually begins in our onboard tank. This means that the free water is going to collect in the bottom of the tank with no convenient way to get it out, creating a fuel/water interface that fosters bacteria growth. And if we ever fail to use a demulsifier additive from then on, that water layer in the tank stands ready to agitate back up into the fuel and make its way to the engine.

3. Use an emulsifier additive. A good emulsifier, according to my understanding, can break the water droplets down into sub-micron size and coat them with a stable, protective film that allows them to pass through to the combustion chamber and be outgassed while minimizing or eliminating abrasive wear on the engine. I still don’t like the idea of water in any form making its way to the engine but this seems to me like the least of the three evils.

The product that I used, in addition to Biobor JF, is StarTron Enzyme Fuel Treatment. If you, Brian, or anyone else researches this or has used it and thinks this or similar products are mostly hype or do more harm than good, I would like to hear about that. I do want to use the best solution available.

Here is a link to the product:
http://www.starbrite.com/item/star-tron-diesel-additive