Do I need a fuel/water separator?

[1970Thunderbird]

Hi all,

I have a 1978, 80hp Mercury outboard that will be running from two 12 gallon plastic, removable tanks. However, I plan on keeping them in the boat permanently unless I have to remove them for some reason. All of my boating will be in freshwater, mostly on lakes.

So, do I need a fuel/water separator? If so, will the basic Attwood one from Wal-Mart suffice? And I've read a lot of opinions, but should the primer bulb be mounted before or after the filter?

Thanks!

 

[jerryjerry05]

Re: Do I need a fuel/water separator?

Yes put one in before the squeezie.Put in a 2 way valve and hard wire all the hoses.That way when you run low on 1 tank just turn the valve and switch to the second tank.J

 

[Dave1027]

Re: Do I need a fuel/water separator?

Yes

22 years on my motor and never had a water separator.
Why does he "need" one? I'm not being argumentative. I sincerely want to know. My guess would be, in case he gets swapped and water get into the tank and then he can get back to the dock?

 

[eye on future]

Re: Do I need a fuel/water separator?

I did not have a water seperator on my mariner 70hp and left the tanks in the boat for the next time, it rained and some water found its way into the tank. I know this because acording to my mechanic that's why when running accross the lake the motor went from 3/4 speed to nothing instantly. On pulling the top plug there was aluminum all over the end of it. Limped back to the launch and did a compression test and was 15 lbs light in that cyl. took some off the top of the piston but did not destroy it. The motor still runs well and I now have a water seperator ( from walmart ) on it. Just in case I would always put one on from now on from what I experienced and what I was told. It was a long walk back to the launch and my water walking shoes were in the garage.

 

[8hygro]

Re: Do I need a fuel/water separator?

The fact is that blended fuels are hygroscopic. In short that means they will absorb moisture right out of the air if it is present. Depending on the transportation and storage of the fuel the problem grows with many uncontrolable variables. If the humidity allows it the fuel will contain water...it is just a matter of how much and where that particular water will end-up and in what quanity.

Water displaces oil. So in a 2 stroke this is an even larger problem. Understanding these fuels have become the standard and not the excetption, I do not know how any manufacturer can not make fuel water seperators standard equipment. I consider it irresponsible.

8hygro

 

[jtsailjt]

Re: Do I need a fuel/water separator?

22 years on my motor and never had a water separator.
Why does he "need" one? I'm not being argumentative. I sincerely want to know. My guess would be, in case he gets swapped and water get into the tank and then he can get back to the dock?

The water in gas usually comes from condensation. That can be from your tanks just sitting in a humid environment (almost anywhere near where you might go boating unless you live in Las Vegas), but it can also come from condensation in the fuel tanks where you buy your gas. When it's warm out, humidity laden air gets in your fuel tank and all would be fine if it stayed warm and in the air. But night invariably comes along and the temperature goes down so less water can stay in the air, so the moisture condenses on the inside walls of the fuel tank and runs down the side to mix with the fuel and sinks to the bottom of the tank where it's trapped and can't evaporate when it all warms up the next day. So when it does warm up the next day, more warm, moister air comes in through your tank vent and the process repeats. Then, you get in your boat and start up your engine and it starts sucking from the bottom of your fuel tank.

You can minimize this effect if you keep your tanks with no room for air (moisture that will condense out) in them when you leave the boat for any length of time, but now using fuel with more of a propensity to separate, you have to be careful about doing that for any extended period of time. Basically, it's inevitable that water will find it's way in. Modern engines REALLY dislike to be fed water even more than their predecessors did!

A water separating fuel filter is a pretty small price to buy some insurance for your engine and I wouldn't have a boat without having one installed.