Water - Fuel - Separator - Theory - ????????

[emilime75]

In theory, let's say you have a source of ethanol free fuel, and the gas station's tanks are perfect and no water ever gets in...is a water separator still necessary?

I'm debating adding one to a Merc 3.0 I just bought. There's at least 2 gas stations near me that offer ethanol free gas. Of course, I have no way of knowing of possible water contamination in their tanks.

 

[GA_Boater]

You're running your boat on a lake with water splashing on your boat or you are caught in a shower, maybe humidity is high or it's a little foggy. Your tank vent is sucking air to make up for the decreasing volume of gas. Do you think only air is going into the tank? No, air and water is going down the vent hose into the tank and over time can accumulate.

I'm not saying you can't get bad gas from gas station, it does happen rarely. The gas station tanks have water sensing and will shut off the pumps, so the chances are slim of getting watered gas. Also, at least when I managed a C-store, tanks are checked manually on a regular schedule checking for water. Most water comes from the air around us or the water we boat in.

Add a water separator/filter. It's cheaper to carry a spare separator/filter cartridge than to fix a motor after the motor is fed with water from the tank. Ethanol laced or pure gas makes no difference - It's what's in the air.

 

[Bondo]

I'm debating adding one to a Merc 3.0 I just bought.

Ayuh,..... Just Do It,.......

GA lays out the reasons,.....

 

[dingbat]

I’ve had two bouts with water in 25 years. Both two weeks apart.

Long story, but the water was the result of torrential rains over a two week period.

The boat was parked (on trailer) leaning to the left which allowed water to puddle in the recess for the gas cap on the top of the gunnel.

The puddling drowned the cap allowing water to enter the system through the cap mounted venting system.

Stumbled upon the problem by chance.

 

[racerone]

There is a lot more moisture in the air around a floating boat than in the air in a driveway 50 miles from a lake.

 

[robert graham]

Just do it....you don't even have to spend a lot of money unless you want to get fancy.....I've used the Walmart/Attwood unit for many years with no problems....about $28, and easy to install....change the cartridge every couple of years....it ain't magic but it works so darn well,,,,

 

[emilime75]

Yes, I've already ordered one and will be installing. Just wanted to fully understand the issue. Thank you.

 

[Scott Danforth]

moisture is in the air...... your tank is vented......tanks breath in and out with temperature changes. as temp drops, the tank draws in air. as temps warm, moisture collects as condensation.

unless you boat in a vacuum completely devoid of air with moisture, you will need a way to get accumulated moisture out of the tank.

 

[Grub54891]

Just a quick note: Even with a water separating filter, if you are not vigilant servicing it or the fuel system itself you can still get water beyond the filter. Seen more than a few the owners haven't changed them for awhile, or the fuel filler cap had leaked as mentioned. A simple o-ring on a cap can shut you down.

 

[Bondo]

Just do it....you don't even have to spend a lot of money unless you want to get fancy.....I've used the Walmart/Attwood unit for many years with no problems....about $28, and easy to install....change the cartridge every couple of years....it ain't magic but it works so darn well,,,,

Ayuh,..... Annually,..... Annual service,.....

 

[Doh]

I have never run a Separator, other than the Fuel Filter Bowl on the Outboard it's self. Draining that Annually, for the last 40 sum years, would not add up to 1/4 cup of water. All I/O's without this type of filter YES definite need for a separator.

I have run E10, for the last 17-18 years (all that is available locally) I run in 30-90F Temps, store the boat Outside in Rain/Snow/Sun, and Transfer fuel from Jerry Cans once in a while. Sunk once on shore, and stuffed the bow 6 times.

Not saying Caution is not Got, but Common Sense helps.

 

[Lou C]

Agreed you replace the filter once a year, and you can dump it out in to a mason jar and let it sit, see if you get a layer of water on the bottom, if not then no worries, if so then you may want to pump out the bottom layer of gas in your tank. I also replace the cap on my old Perko gas fill every few years. Have never seen water in the gas but using E10 of course some could be in suspension and I would not see it. The winter cover I use covers the gas fill so that helps with winter storage....

 

[robert graham]

I cut my cartridge filter open once several years ago just to see what was inside....looks for the most part exactly like an automotive oil filter....pleated media....I'm confident the media materials are different but very similar. My motor is a 90HP with a 12 gallon portable tank so water intrusion is not much issue, but an inboard/outboard, built-in tanks water can be a real killer issue....

 

[Scott06]

I'm debating adding one to a Merc 3.0 I just bought. There's at least 2 gas stations near me that offer ethanol free gas. Of course, I have no way of knowing of possible water contamination in their tanks.

Unless your 3.0 is mpi you have a filter and water separator in the bowl on the bottom of the fuel pump. Take a look at yours. A bigger canister style filter like on larger engines won’t hurt either.

 

[emilime75]

Unless your 3.0 is mpi you have a filter and water separator in the bowl on the bottom of the fuel pump. Take a look at yours. A bigger canister style filter like on larger engines won’t hurt either.

I'm aware of the filter on the bottom of the fuel pump, and a new filter kit for it is being delivered today...but, from what I understand, it really isn't a water separator.

Also, maybe this should be a different topic, but since we're talking fuel and water and E10... I've seen some mentions of people running 91 and 93 octane gas in their carbed motors. Seems like that's wrong for a motor with a CR in the low 9s. Pretty sure the ethanol free stuff around here is 87, maybe 89, I'll have to confirm.

 

[racerone]

Nothing wrong with running 91 or 93 octane in an outboard motor.----No damage will result.

 

[dingbat]

A word to the wise....all filters are not “separating” filters and as with everything, not all filters are designed or created equally.

Three principal qualities of a filter
1. Minimum particular size: the filter will pass typically 2 micron, 5 micron and 10 micron

2. Removal Efficiency: how much of the water do they trap
Varies from 12% to 99.8%

3. Pressure drop thru system: most give clean and max. filter restrictions. The lower the better

A number of your better filters use a treated filter media as part of the coalescing process. Regular maintenance intervals are key to maintaining the efficiency.

Dumping a filter of any type then reusing is the worst thing you can.

 

[emilime75]

Nothing wrong with running 91 or 93 octane in an outboard motor.----No damage will result.

But I'm talking about an I/O, hence it being in the I/O section

In my particular case, a carbed 3.0.

Generally speaking, running relatively high octane fuel, in relatively low compression motors, is not advised. Mainly because the spark, without the extra compression, sometimes isn't enough to ignite the fuel.

 

[racerone]

Are you sure on those facts ?

 

[Grub54891]

The only thing I run premium in is my yard equipment. Everything else is regular unleaded. Not an issue in years.