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1995 Montauk w/ 1995 Johnson 88 SPL.
When I bought this boat this Spring it had a stubby Sierra Fuel/Water seperator on it. During Spring prep I replaced the filter with the same 10 micron sierra however I noticed that the fuel exiting the filter was more yellow than the pre-mix fuel entering the filter.
I ended up replacing my fuel tank and lines for other reasons but did not hook the fuel/water seperator back up. I use my boat alot so I am constantly cycling through tanks of fuel.

I would like to install a fuel/water seperator, any suggestions on what to use brand and micron size? I have read that 10 microns will not filter the oil from premix fuel however the different color of the fuel exiting the Sierra 10 micron filter had me slightly concerned.

Does anyone run a 21 micron size filter on these older motors? Any info would be appreciated.

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Why didn't you hook the old fuel seperater back up?

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A water seprating fuel filter is a waste of money and unnecessary clutter on a Montauk, or any other boat using on-deck fuel tanks. On deck tanks don't collect any condensation water. Only boats with aluminum belly tanks need those filters, since they are the ones that could possibly collect condensation during winter, or extreme rapid temperature variations.

As you know, Boston Whaler now sells fully rigged boats, and those with on-deck tanks don't come with a water separating fuel filter. Larger Whalers with belly tanks do.

I have a Montauk, and an old ribside 21 Outrage, both with only on-deck tanks, and I do not use any of these filters. No problems.

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Good advice. I have been searching this topic all over the internet and Tom W Clark echoed your statement regarding above deck tanks.
I have a above deck 24 gallon white Moeller tank that is covered by my RPS seat cover when the boat is not in use so water infiltration is limited.

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The question of whether to use a water separating filter is hotly debated.

New motors include a 10 micron filter under the cowl.

Personly I have one as insurance. I also carry twice the required number of flares and 8 lifejackets even though my boat only holds 6.

You decide.

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I agree with the condensation point, but I have had other issues with water in my 6 gallon plastic tanks.

I had a bad O-ring in tank vent and the vent became fouled. In the hot sun, the vapor in the tank expanded and pressurized the tank. Some fuel/oil mix blew by the OMC fuel fitting. Once the afternoon thunderstorm rolled through, the tank became wet and the fuel vapor cooled and contracted, drawing a vaccuum in the tank. This vaccuum pulled rainwater directly into the fuel line via the the fuel line fitting. The next time I tried to start the motor, I gummed up the carbs pretty bad and had to un-stick 2 of 3 needle valves and found lots of water in the bowl of the 3rd. This is also what can happen if you or someone else accidently leaves the tank vent closed.

So now I use a low profile Racor fuel water separator with the sight glass type bowl. 10 micron. It fits cleanly above the splashwell and adds no clutter at all. Now that I know how to rebuild a carb, hopefully I won't be doing it again any time soon.

Also, if the filter gets clogged somehow, I can patch the tank directly to the motor and not worry about switching the filter under the cowling out while on the water.

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The condensation logic is great but having owned a montauk in the pre ethanol era for 12 years I would never run it without the separator. Gas tanks develop leaks, forget to tighten up your vent cap at the end of the day? No thanks. After being towed 3 times over two seasons I invest in a racor see thru bowl, no more tows.

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If you are running ethanol gas in your boat, you need a fuel/water separator. Period. Back around 2010, Yamaha tested gas from stations all over. The average amount of ethanol they found was around 22%. Not 10%, but 22%. In addition, they do NOT honor any ethanol related problems under their warranty.

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I agree with those that support the use or a fuel water seperator, regardless of whether your tank is above or below deck. Above deck tanks get water in them too, rain, open vent, hosing the boat down, water in fuel from fuel dock, etc. Can't count the number of times I have had to clean a carb because of water and no water seperator. Of course you have to keep eye on the sperator and drain off water from time to time. Failure to do so will result in the filter being full of water and then overflowing into fuel supplied to engine.

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I have and always will have a Racor filter water seperator in use. Here's my reasoning: 1st & foremost, the underground tanks we get our fuel from DOES condensate and contains some degree of water, particularly w/ethenol fuel. 2nd, my new white Moeller 24 gal tank is vented, I live in the South and the humidity can get unbearable, which means some amount could get into my fuel. 3rd, I believe the filtration is better for dirt/stuff that may be in the fuel. I subscribe to the pay me now or pay me later principle. And now I'm going almost all ethenol free fuel. As for the space issue, it's never been one where I have mine located (see personal page photo). Good Luck!

One Man's Opinion

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Tommy, can you send a pointer to any info about the Yamaha test? Interesting.

Tim

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Fuel with 22% ethanol content would not run an engine. It would stall/choke/die etc. Ethanol content is fairly regulated in the large suppliers.

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Brazil has a gasoline-ethanol fuel that varies with 21% to 25% and it works in outboard motors. The problem is when the fuel left in the tanks gets older than 30 days, it will absorb enough moisture to phase separate and that water-alcohol compound that settles to the tank floor will damage the rubber components if left for a while. In many areas, the boat tanks have to be emptied monthly and the motors flushed with fresh fuel.

Hardly any Brazilians are weekend trailer boaters, so most of the more privliged have people who do that for them. One dealership keeps over 100 carburetor kits in stock to service his clientele who don't constantly maintain their boats.

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For 2 years now Yamaha requires any prerigged Yamaha Outboard to have a 10 micron fuel filter installed and in use. No 10 micron fuel filter = no warranty at all. Can they enforce this? I do not know, but I would not want to be the test case. I know this applies to engines of 40 horsepower or more. I have no exposure to smaller engines so I do not know if it applies to them.

I also know that Yamaha changed the on engine fuel filters to meet the 10 micron standard. This is an expensive change over as it requires a new housing.

Just another factoid, Sierra made all Yamaha 10 micron canister filters as of 18 months ago. I believe they still do today.

My recommendation is that this is one of the stupidest places to try to save a few dollars. I am now retired, but the dealership I worked at got more than 50% of its service work over the last couple of years from ethanol problems.

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10 gallons of E85 worked pretty well in a 2005 Jeep Wrangler I rode in during a hunting trip. No obvious issues running several miles of logging trails and a few miles of Interstate before the owner could refill with E10. Thats a lot more than 22% ethanol. However I'm sure there may be long term consequences of having to resort to the E85 when the owner allowed the Jeep to run out of gas. Maybe the engine management system was able to partly accommodate the E85 by richening the fuel mixture.

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I am using a 10 micron Racor on premixed fuel without any issues. The oil stays mixed.

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It would be helpful to hear from those who use the water separating filters on their Moeller/Tempo plastic tank equipped boat as to the amount of water they routinely find in the filter. That might help to convince me that I should install one also. But so far, since 1970, I have yet to have an engine not run because of water in the gas.

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I installed a ten micron Sierra filter on my boat a year and a half ago. I have a six gallon Tempo portable tank under the console. Last fall when I changed the filter I poured it out slowly into a container to see what was in the bottom. It was as clean as the day I installed it. There was no water in it. A good fuel filter is still worth having. You just never know what will make it's way into your fuel tank.