What’s Up with The Cloudy Fuel in My Marine Outboard Gas Tank?

Boats are supposed to be for pleasure…….that is why the boating industry coined the phrase “Pleasure Boating” and taking a “Pleasure Cruise”.  However, since the congressional acts some 13 years ago that brought in Ethanol Blended Fuel into the marine market,  many “Pleasure Cruises” and Family Boating outings have turned sour due to water contaminated fuel.  Even if the serious boater purchases “Rec Fuel” which contains no alcohol,  there still can be water contaminated problems.
This article / blog post will help shed some light on what causes such problems and what boaters and service techs can do to minimize the problems.  First, let’s explore some issues.
 
How Does Water Get Outboard Motor Fuel Tanks?

1.  Gas Station Fuel Fill Ups.  Most gas stations tanks both get water in the delivery (known or unknown) and accumulate some their own in many ways including condensation as ground temperature is different than ambient temperature.    The vents also can take in moisture, particularly at busy stations with high throughput.  Gas Stations are receive water through spill buckets and delivery drivers in a hurry

1. General Condensation. from different temperatures of the fuel tank and ambient air.  Picture a boat in elevated  storage center.  Often the temperature is five degrees hotter than the ground.  Just ask an overhead crane technician.    While most people think of Denver and Phoenix as dry places, they do have considerable changes in the daily temperature which contribute to corrosion.

Temperature Change with Higher Elevations

Fill Cap On Gunnel of Mako 17

• Fill Caps. For one reason or another, the fill cap for many pleasure and fishing boats sits horizontal, often on the gunnel.   This scenario can test the best of designs and gasket technology…….even with a raised receptacle.  Heavy rains and splashing can show no mercy, and water can creep in.

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​Why Is My Fuel Cloudy Sometimes, But Other Times Clear?

•  Specific Gravity. Water has a specific gravity of one, and the alcohol and fuel components are less than one.  So conventional wisdom says that water should sink and settle to the bottom. With the ethanol blends comes alcohol from corn or sugar.  It is this alcohol molecule that can bond to the water molecule and cause the water droplets do not become heavy enough to sink, thus you have hazy fuel.

• Agitation.   Boats that run frequently or in choppy water can stir the water molecules and cause them to “hang” in the fuel column.

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• Additive Packages.   Todays modern fuels have additive packages from either the refinery or the terminal.  Some additives include a) cold flow improvers b) defoamers c) detergents and d) performance enhancers.  These coupled with aftermarket additives can create some unintended consequences which can contribute to hazy fuel.

 

What Is So Bad About Suspended Water in My Fuel????
 

•  Performance.   Lack for full fuel burn and reduced compression.   Fuel needs to be at its hottest temperature to completely burn and work as it is supposed to.  But water cannot be compressed, and water will not burn. These factors lead to black smoke, loss of power and hard starts.

 

• Abrasion. Suspended water can also cause damage to metal parts through abrasion.    Just look at river rocks that are round from hundreds of thousands of gallons water running over it and you will see a smooth abrasion.  Now take water and force it under pressure. Over time, water caused abrasion can wear components down.

 

• Corrosion.  Water molecules can sit in various parts of the fuel system and cause damage. The corrosion damage can also be on Steel and Fiberglass…..no material is spared.   This is also in part due the microbes in the organic corn and sugar can excrete an acid, which also can contribute to a lower pH and accelerate corrosion.

 

Corrosion on Fiberglass (l) and Steel (r)

But What if I Already Have Fuel Water Separators to Catch Water? Won’t That Stop Water Entering My Engine?
 
Not all fuel water separators work the same or catch all the water.  Yes, you can buy a nice exterior fuel water separator that is easy to install, and has a clear bowl to let you know the water has been caught.  However, what this type of filter does not tell you is how much water was able to get through to the engine.  One principal used by fuel water separator manufacturer’s is called “coalescing” or the use of a coalescer.  This technique takes small droplets and has actions to form them into bigger droplets, which when are directed to the outside of the filter housing.  This water then falls down to a bowl and is easily drained with a pet cock valve.  So, if you have such a fuel water separator, and you are experiencing poor performance, hard starts or black smoke, plus injector damage, it might that small water droplets are passing through and wreaking havoc.

Examples of filters with glass bowls...how much water is getting through?

So, What Are Some Steps I Can Take to Prevent and Remove Water, So I Don’t End Up With Water Contaminated Hazy Fuel in My Outboard Engine?

1. Block Water From Entering Through Fuel Cap.  Use Steel Camel’s AquaBlokker, water absorbing and grease every around the cap every time you fill.  For about a dollar a fill, you can save yourself a lot of headaches.  The grease also helps prevent wear and makes caps easier to get on and off.

 

• Choose Your  Exterior Water Separating Fuel Filters Wisely and Avoid Glass Collection Bowls Where You Can.  Some factors you should consider are:
•  How much water does the water separator hold?   There is a huge difference between 4 ounces of water and 10 ounces of water in the same size filter.

 

•  How well does the plugging feature work to alert the operator of troubles in the tank.  A filter should begin to reduce flow as it fills up with water and debris to.  Some swell better than others.  While changing a plugged filter can be bothersome, it sure beats engine damage and or being stranded.

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•  If your boat sits for a long time and the fuel is dropped straight into the tank without an elbow or anti-theft device,   you can drop a Steel Camel water absorbing sock into the tank.   Let it sit for a few days and it will attract and hold water.  Simply pull it out and hang it in a warm dry place, and it can be reused after a few weeks.

Water Absorbing Socks for Ethanol Fuels

Which filters are letting water through to the engine?

• Consider a water absorbing filtering fuel transfer pump kit.  This consists of a explosion proof, gasoline rated transfer pump such a the Fill Rite RD 8, fuel rated hoses, grounding straps and battery connectors.   You will need a few adjustments / bushings to tie into the inlet hose going into the engine, and the outlet hose will go back into the fill port.  Run it for 30-60 minutes and you should be good to go.

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Fillrite RD 8 and Steel Camel Filters getting it done

Summary:
 
Water is meant swimming in pools, drinking, cooking, washing, sustaining life and many other great things. It has no good reason to be in outboard motor fuel tanks.  Whether you are a boat dealer, marina, boat captain or service repair shop,  pay attention to water and your headaches will go away.