Small outboard fuel water separator?

[gbillman]

Is there such a thing as a fuel water separator that splices into the line from fuel tank to motor for a small outboard (i.e. Yamaha 15hp 2 stroke)? I've got an in-line filter now, but was wondering if I'd be better off with a water separator (given the propensity of small outboard carbs to corrode internally with even small amounts of water). Thanks.

[rslifkin]

You could put one of the small Racor or other spin on filters meant for gasoline in the line. It's certainly not a bad idea and I've considered it for my dinghy as well.

[Orion Jim]

Racor model 120R-RAC-01 is available at numerous retail and online sources.

[thinwater]

It won't work. Raycors and other separators do not function properly on e10 gasoline.

• The water phase is so high in ethanol there is barely any difference in relative density.
• The difference in surface tension between gasoline and e10 water (which is 80% ethanol) is too small for the filter media to reject it. It passes through.
• Water can pass through disolved.
• The separation often occurs in the carb itself, after the filter, where gasoline is exposed to humid air.

The solution is to keep the tank DRY, just like your car. Keep the vent closed when not in use. Keep the tank out of the sun (cover it) to minimize pressure buildup. Then use an anti-corrosion additive, such as Biobor EB, Merc Stor-N-Start, or Stabil 360 Marine (many gas additives are snake oil--these I have tested in the lab and on the boat).



When e10 first came out I learned all about separation and corrosion. Lots of problems. I did a lot of testing and found solutions. I have not had a carb problem in the 30 years since.



(Chem enrg from the fuels industry that has tested this in the lab and on several boats since e10 came out)

[cr180]

Raycor also makes a very small filter and water separator model #025-rac-02. I have one in line, no bulkhead mounting required. Tie with small cord to tiller handle. Have had good service from the unit for a number of years.

[Phyrcooler]

Originally Posted by thinwater

It won't work. Raycors and other separators do not function properly on e10 gasoline.

• The water phase is so high in ethanol there is barely any difference in relative density.
• The difference in surface tension between gasoline and e10 water (which is 80% ethanol) is too small for the filter media to reject it. It passes through.
• Water can pass through disolved.
• The separation often occurs in the carb itself, after the filter, where gasoline is exposed to humid air.

The solution is to keep the tank DRY, just like your car. Keep the vent closed when not in use. Keep the tank out of the sun (cover it) to minimize pressure buildup. Then use an anti-corrosion additive, such as Biobor EB, Merc Stor-N-Start, or Stabil 360 Marine (many gas additives are snake oil--these I have tested in the lab and on the boat).



When e10 first came out I learned all about separation and corrosion. Lots of problems. I did a lot of testing and found solutions. I have not had a carb problem in the 30 years since.



(Chem enrg from the fuels industry that has tested this in the lab and on several boats since e10 came out)

Interesting. I guess a separator is still viable for anyone that can still procure alcohol free fuel. The other suggestion IMHO is using a smaller tank unless you truly need the range. Keep it full until used - cycling fuel through it faster.

[wrwakefield]

We have used these particulate filters for decades on our Yamaha 15 2 stroke.




I don't think they separate any water, but we have not ever had any issues with water contamination reaching the motor.

We do not (yet) have any ethanol in our gasoline this far north, and I always add Seafoam (1oz/gal) to outboard fuel when it is purchased.

In case this helps.

Cheers, Bill

PS: We have not had any corrosion in the carb or anywhere in the fuel system, and this outboard has been in use almost full time since it was purchased in 2006.

[Cheechako]

I had a Racor one on my dingy with a 15hp Yamaha. It's a spin on with a clear bowl. It's not super small though, maybe 3" diameter x 5-6" tall.
I wouldn't worry a lot about water in your dingy fuel though, unless you are careless. It get's used pretty fast and the tanks are tight.

[GreenWave]

Originally Posted by thinwater

It won't work. Raycors and other separators do not function properly on e10 gasoline.

• The water phase is so high in ethanol there is barely any difference in relative density.
• The difference in surface tension between gasoline and e10 water (which is 80% ethanol) is too small for the filter media to reject it. It passes through.
• Water can pass through disolved.
• The separation often occurs in the carb itself, after the filter, where gasoline is exposed to humid air.

The solution is to keep the tank DRY, just like your car. Keep the vent closed when not in use. Keep the tank out of the sun (cover it) to minimize pressure buildup. Then use an anti-corrosion additive, such as Biobor EB, Merc Stor-N-Start, or Stabil 360 Marine (many gas additives are snake oil--these I have tested in the lab and on the boat).



When e10 first came out I learned all about separation and corrosion. Lots of problems. I did a lot of testing and found solutions. I have not had a carb problem in the 30 years since.



(Chem enrg from the fuels industry that has tested this in the lab and on several boats since e10 came out)

Thought we just settled in another thread that you should just use ethanol free gas in your outboards!? 😀

[cr180]

Several points:
1. Don’t know about water solubility in ethanol fuel and if it can be separated by water separator. But as others have said, plenty of reasons not to use ethanol fuel. Not a reason not to have a water separator.
2. Not embarrassed at all to say that I have had outboards run rough and fail to start due to water in outboard fuel. And have observed many cruisers in Florida and Bahamas do as well. A leading cause of outboard problems.
3. Try as you will, in the semitropical climate can’t keep water out of tanks. If a rain shower doesn’t get you, then condensation surely will.
4. A water separator has worked for me.

[geoleo]

Originally Posted by Phyrcooler

Interesting. I guess a separator is still viable for anyone that can still procure alcohol free fuel. The other suggestion IMHO is using a smaller tank unless you truly need the range. Keep it full until used - cycling fuel through it faster.

Go to WAWA and get non E-10 Gas.

[thinwater]

I'm not sayin' an external filter is not a good idea. Clean fuel is perhaps the most important factor in reliable operation, and poor filtration one of the greatest failings of smaller outboards. In fact, some very small outboards do not have a micron-rated filter at all, only a strainer in the bottom of the integral tank. In that case, even an in-line lawn mower filter is a great improvement.


Non-ethanol gas is obviously not the only solution. I've used e10 in multiple small engines since it became dominant locally 35 years ago. It runs fine if you follow the rules. Not worth serching out ethanol free, which is scarce as hen's teeth many places. The nation's fleet of cars runs just fine on it. I'm not a fan of ethanol's political history, but it runs fine if you keep it dry. Of course, the same design features that minimize evaporative emissions keep the water out. If ethanol-free is readily available to you, you are lucky and by all means should use it.



Portable tanks are not designed to be vented in the rain or spray. Sad, but true. You really need a cover of some sort. Either keep the tank under a seat or make a cover. Water will stop either e10 or e0. Rainwater is the leading source of water in fuel, not humidity.



I've had Raycor units on outboards, two different boats, for 15 years. I never collected one drop of water. On the other hand, I have had in-line filters clog with emulsion and who knows what. I always carry a spare. For smaller motors, they're just lawn mower filters, quite cheap.