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  1. #1
    Lieutenant Commander flashback's Avatar
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    Default fuel filter/water separator question

    A couple actually.. Have any of you guys ever cut one open, how do they separate the water from the fuel? The other question is can i reuse one that has loaded up with water and not separating anymore if I empty it and let it dry out for a while...? This is on a 1979 350 merc I/O
    The Devil to pay, and no pitch hot!

  2. #2
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    Default Re: fuel filter/water separator question

    I haven't bothered to cut open a fuel filter, I have opened oil filters looking for see if metal particles where present from excessive wear.

    Think of a filter as a VERY fine window screen, the 'holes' are so small that they filter out everything too large to pass. Most filters are made of a paper material, the water droplets are larger than gasoline and are filtered out, a certain amount of water is also absorbed in the paper, causing it to swell, reducing the size of the holes until nothing can pass through it.

    Poring out the water and allowing an adequate amount of tiime you 'may' restore a small amount of 'flow' however the paper will NEVER recover its original flow capacity, you will NOT get full flow and may end up running the engine 'lean' which will damage the engine, bad.

    Replace the filter and carry a 'spare', cause its just a matter of time, you will need to change it again.

  3. #3
    Lieutenant Junior Grade sickwilly's Avatar
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    Default Re: fuel filter/water separator question

    I put a screwdriver through mine to remove it, but it seemed like gas and not water poured out.
    2004 Stingray 190LX, 4.3 Merc, carb, SE Sport Hydrofoil

  4. #4
    Moderator achris's Avatar
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    Default Re: fuel filter/water separator question

    Quote Originally Posted by flashback View Post
    ...can i reuse one that has loaded up with water and not separating anymore if I empty it and let it dry out for a while...? ....
    You're willing to risk several thousand dollars worth of engine just to save $10 on a filter.... You deserve all you get!!!

  5. #5
    Petty Officer 1st Class wil7483's Avatar
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    Default Re: fuel filter/water separator question

    Ditto..............what is the point of trying to reuse it? It is an expendable item meant to be thrown away and replaced. Spend the 10 bucks and buy another one. Heck, like the previous poster said, buy 2, have a spare one on hand.


    1988 Wellcraft Elite 222 XL w/ 350 5.7 SBC and Alpha One

  6. #6
    Moderator Bondo's Avatar
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    Default Re: fuel filter/water separator question

    Ayuh,....

    The short answer is,.. No..... just like everybody is saying.....

    But,.... I'll tell ya alittle Story.............

    Years back when I went thru the Maineiac the 1st time,....
    I replaced All of the rubber parts in the fuel system,... When I put the fuel tank vent line in, I put it Straight to the vent fitting..... I suffered thru Wet filters forever,... I would rotate them thru use, by the time the 3rd, or 4th were full of water, the 1st 1 would be Dried out,.....
    Finally,.....
    I pulled the vent lines,+ put a Loop in them,......
    No more wave splashs washing into the fuel tanks,... No more need to rotate dirty filters.....
    Now I replace,+ toss the old 1s, a couple of times a year..............
    After I dump it to See what's hiding in there of course..............
    Any Grease is Better,..... Than No Grease at All.......

  7. #7
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: fuel filter/water separator question

    And in the process of dumping out the old dirty, watery, fuel from the old filter. 9 times out of 10 dirt gets moved to the wrong side of the filter so it heads for the fuel pump and carb.
    You might get away with reusing for a while, but it will catch up, and it may be what costs you a new carb. You can buy a LOT of filters for the price of a carb these days.
    Don S.


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  8. #8
    Lieutenant Commander flashback's Avatar
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    Default Re: fuel filter/water separator question

    Thanks for the info folks,,,Pretty much what I expected but I just wanted to ask....Last year I had just put a new one on, and the next week, got a hold of some watered down gas and had to replace it,,, I emptied it and set it on a shelf in my basment and was looking at it the other day and, well you know...
    The Devil to pay, and no pitch hot!

  9. #9
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: fuel filter/water separator question

    Get the water out of your tank, then you wont be getting your filter full of water. That water will also corrode the INSIDE of the tank.

    If you have water in the tank, see if this thread will help.
    http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/water-fuel-212830.html
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
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  10. #10
    Lieutenant Commander flashback's Avatar
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    Default Re: fuel filter/water separator question

    Hey Don, Thanks for the tip, I have a full tank at the moment and the boat is pretty much buttoned up right now.. I happen to have a fuel pump laying around somewhere, (just gotta find it)..Once the weather breaks, I'll run some gas out and give it a shot... Good to be back, Had a lot of crap going on last year and sorta lost touch..
    The Devil to pay, and no pitch hot!

  11. #11
    Lieutenant Commander flashback's Avatar
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    Default Re: fuel filter/water separator question

    Quote Originally Posted by achris View Post
    You're willing to risk several thousand dollars worth of engine just to save $10 on a filter.... You deserve all you get!!!
    Chris, your still just as salty as you ever were...
    The Devil to pay, and no pitch hot!

  12. #12
    Lieutenant Commander flashback's Avatar
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    Default Re: fuel filter/water separator question

    Quote Originally Posted by Bond-o View Post
    Ayuh,....

    The short answer is,.. No..... just like everybody is saying.....

    But,.... I'll tell ya alittle Story.............

    Years back when I went thru the Maineiac the 1st time,....
    I replaced All of the rubber parts in the fuel system,... When I put the fuel tank vent line in, I put it Straight to the vent fitting..... I suffered thru Wet filters forever,... I would rotate them thru use, by the time the 3rd, or 4th were full of water, the 1st 1 would be Dried out,.....
    Finally,.....
    I pulled the vent lines,+ put a Loop in them,......
    No more wave splashs washing into the fuel tanks,... No more need to rotate dirty filters.....
    Now I replace,+ toss the old 1s, a couple of times a year..............
    After I dump it to See what's hiding in there of course..............
    I'm pretty sure I got the water at the pump, as I have not ever had a problem before, This happened early in the season last year, The marina has an above ground tank and I suspect they picked up a little water over the winter..I did have a spare with me, and it worked fine the rest of the summer, but I'll get in there and pump the bottom out just to be sure..Hey how did you ever come out on that house jacking project you had?
    The Devil to pay, and no pitch hot!

  13. #13
    Commander Lou C's Avatar
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    Default Re: fuel filter/water separator question

    Trailer boats mag had a test on those filters some time back, it's floating around somewhere on the net, I recall that they could hold between 15-22 oz of water before passing water into the fuel. The way they are made, the paper filter portion extends about 2/3 down from the top, below that is an empty space where the water drops to by gravity and water molecules are heavier than gas. But if that area fills up, then water will be passed thru into the fuel. The RACOR filter held the most, if you use one in an IO you need to use the metal bowl version, nice thing is you can drain it from the bottom without removig the filter, but they are a lot more expensive and take up more room.
    1988 Four Winns 200 Horizon
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  14. #14
    Moderator Bondo's Avatar
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    Default Re: fuel filter/water separator question

    Hey how did you ever come out on that house jacking project you had?
    Ayuh,..... Still pecking away at it,..... Been doing my best to stabilize the structure that's going up,+ removing the stuff that isn't.....

    Biggest problem is things like other projects,+ Work keep getting in the way......
    While I'd hoped that things would be farther along by now,... I'm still within my 3 to 5 year time frame....
    Any Grease is Better,..... Than No Grease at All.......

  15. #15
    Petty Officer 1st Class ted655's Avatar
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    Default Re: fuel filter/water separator question

    One of the best things to own is a "Baha" funnel. I own a cheap ($20) plastic 8" type. Nothing goes into my tanks unless it passes through the funnel.
    Ted says, "IF, it has tits, tires or a transom, there's gonna be problems!"

  16. #16
    Lieutenant Commander flashback's Avatar
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    Default Re: fuel filter/water separator question

    Quote Originally Posted by ted655 View Post
    One of the best things to own is a "Baha" funnel. I own a cheap ($20) plastic 8" type. Nothing goes into my tanks unless it passes through the funnel.
    Thanks Ted, I have one now.. west sells them for about 15 bucks if anyone is interested...
    The Devil to pay, and no pitch hot!

  17. #17
    Lieutenant Commander flashback's Avatar
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    Default Re: fuel filter/water separator question

    Quote Originally Posted by Bond-o View Post
    Ayuh,..... Still pecking away at it,..... Been doing my best to stabilize the structure that's going up,+ removing the stuff that isn't.....

    Biggest problem is things like other projects,+ Work keep getting in the way......
    While I'd hoped that things would be farther along by now,... I'm still within my 3 to 5 year time frame....
    Yea, traveling around the lakes in that houseboat does take up a lot of time..
    The Devil to pay, and no pitch hot!

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