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Catalina/Capri 25/250 Sailor's Forums

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Fuel Filter/Water Separator

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OLarryR
Master Marine Consultant

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USA
3429 Posts

Initially Posted - 12/28/2007 : 11:34:14

I was talking yesterday with a co-worker who has a motorboat with an outboard motor. We got around to talking about water separators. Is this found to be an important thing to have ?

I have a 3 gallon tank with a 2006 Honda that runs flawlessly. In practice, I add ..believe it is called Startron or something to each fill-up. It is an enzyme based product that keeps water from forming and prevents the gas from turning to shellac in the gas lines. I also when returning to the dock, always run the gas out of the motor by allowing the motor to run without the gas line hooked up to it. The gas generally never sits in the tank for longer than about 1 1/2 mos and that is more during the winter season.

If having a separator is a good thing to install in the line, what have others used and where did you connect it into the line ? Is it mounted against a sidewall ? How often is the maintenance to this thing or you just look at it and see if there is water in it ?

Not really knowledgeable on this - have not looked into it. Should I ?

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/28/2007 : 12:18:01

IMHO: Keep your fuel tanks full and water contamination shouldn't be a problem. Most of the water entering the fuel system comes from condensation of atmospheric moisture on the interior surface of the fuel tanks.

Minimizing the amount of air in the tank minimizes the amount of moisture that can condense.

Edited by - on

GaryB
Master Marine Consultant

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USA
4300 Posts

Response Posted - 12/28/2007 : 12:54:21

Larry,

I don't think a water seperator is needed under the conditions your using you motor. Unless you have a built in tank of larger capacity (20-100 gallons) than we use on our boats and/or you don't use it regularly you might have a problem with water. I've had a 21' SeaRay with a 44 gallon built-in tank since 1989 and I've NEVER had a problem with water in the fuel. Even after letting it sit all winter.

On my C25 I'll run my 4 gallon tank down almost to empty every couple of months and then dump what's left into a gas can I use for my lawn mower. I haven't been using any kind of fuel conditioner but plan to in the future.

BTW, diesel fuel requires you use a water seperator because the fuel injection pumps can be destroyed with even small amounts of water and a biocide is necessary to keep algae from growing in the fuel and tank.

GaryB
'89 SR/WK #5862
Kemah,TX

Edited by - GaryB on 12/28/2007 12:55:19

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 12/28/2007 : 13:43:31

I don't think you need to run the gas out of the carb after each and every outing, especially if you are sailing three or four times a week. I run the gas out only at the end of the season and have never had any problems.

Edited by - on

DaveR
Master Marine Consultant

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USA
2015 Posts

Response Posted - 12/28/2007 : 14:00:11

In salt water you might as well run the gas out of the float bowl because you need to run fresh water through the motor anyway and it's a good habit to be in. But I believe Larry is in fresh and sails quite often so neither the separator or running the gas out is absolutely necessary. Still,

in 10 years time I'll bet I can easily tell the difference in a carb that HAS run the gas out each use verses one that hasn't.

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 12/28/2007 : 14:41:57

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DaveR
 Still,

in 10 years time I'll bet I can easily tell the difference in a carb that HAS run the gas out each use verses one that hasn't.<hr height="1" noshade id="quote"></blockquote id="quote">

Dave,

Last year, I dismantled the carb for the first time on my 11 year old outboard and I was amazed at how good it looked. It looked brand spankin' new on the inside with no varnish, no gunk, no nothin'.

If you apply what Clambeach stated about keeping things full of fuel, what would be better, to have your float bowl, fuel lines, and fuel filter filled with fuel or moist air?

(Personally, I think the "running out the fuel after every use" is a bit of an old wives tale and a waste of gas.)

Edited by - on

OLarryR
Master Marine Consultant

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USA
3429 Posts

Response Posted - 12/28/2007 : 15:02:07

Hmmm.....a number of good points. okay..so no separator. But...I now have to rethink this thing with running the gas out of the engine. I understand the point made...why not have fuel in there versus air that could then cause moisture/condensation. This also being the case regarding the fuel tank. I am in the habit of running the gas out...in fact...oftentimes I take the fuel line off the motor as I am approaching my slip. Yeah...I know that makes no real sense except by the time I get ready to leave the boat, the motor then konks out and I can raise it and that's that for the day. Probably all-around better idea to leave the line on till I am tied up and then just shut the motor off and disconnect the line.

I'll do it !

Edited by - OLarryR on 12/28/2007 15:03:08

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 12/28/2007 : 15:36:47

The thinking behind the old 'run the gas out of the carb' advice was that evaporating fuel leaves behind a slight residue of oil and other compounds that dry to produce a thin brown film called 'varnish'.

Repeated carb drying cycles would 'varnish the carb up'. I haven't found this to be a problem with modern fuels and engines. I just shut my engine off, then disconnect the gas.

Edited by - on

glivs
Admiral

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USA
836 Posts

Response Posted - 12/28/2007 : 17:48:12

Larry,
Do a search for "inline filter" from last year.
After having condensation problems one year, I top the tank off periodically through the season. I'm also a firm believer in a simple inline filter to trap particulates. So far so good...

Not to steal this thread, but anyone know how I can assign the search result link to text I want to avoid pasting in a long address, i.e.
inline filter as opposed to:"http://www.catalina-capri-25s.org/forum/topic.asp?......

Edited by - on

jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 12/28/2007 : 19:25:40

OK - so I'm confused - given the above testimony...the 2007 Merc 4/s, 8HP o/b I got at the beginning of the season last year recommends runnning the engine dry...why would they suggest that?

Edited by - jerlim on 12/28/2007 19:26:39

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 12/28/2007 : 19:29:10

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jerlim
 OK - so I'm confused - given the above testimony...the 2007 Merc 4/s, 8HP o/b I got at the beginning of the season last year recommends running the engine dry...why would they suggest that?
<hr height="1" noshade id="quote"></blockquote id="quote">

After each use?

The Honda manuals I've read only say to drain the bowl at season's end. I didn't see anything recommending running the engine until dry.

Edited by - dlucier on 12/28/2007 19:38:14

Leon Sisson
Master Marine Consultant

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USA
1892 Posts

Response Posted - 12/29/2007 : 00:18:40

Well, to further muddy the water (in your fuel systems

), here are my thoughts on water based gas contamination. A whole lot depends on the specifics of your individual situation, which may be one reason why the advice and testimonials are all over the map (so to speak).

I live in a tropical climate a few blocks from the ocean, which is the context for my experiences and recommendations. Here, humidity is not only high, it's frequently at or above 100% in the form of mist with high concentrations of salt. I used to have terrible problems with water in my portable outboard fuel tank. I tried the glass-bodied inline fuel filters about the size of flashlight batteries, even two in series. The crud at the bottom of the tank would still overwhelm their capacity. I finally resorted to a Racor-style remote filter with spin-on element and clear sediment bowl. I also became fanatical about running the carb float bowl dry after each use. Since then, I haven't had any significant reliability issues caused by fuel contamination.

As engines become more fuel-efficient, the fuel metering orifices get smaller and more sensitive to contamination. Even if you didn't have a problem with your old 2-stroke, don't count on the same fuel contamination management practices to keep your new 4-stroke happy.

-- Leon S

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 12/29/2007 : 11:25:30

Like Leon, I installed a good-sized Racor in Passage--as insurance. The mechanic at my dealer (who writes for some boating mag) told me that the latest thinking, because of E-10 gas, is to put Startron and a half-dose of stabilizer in with every fill during the season, and definitely to not run the carb dry. The belief is that the stabilized fuel in the carb is better than the film of fuel that remains and then evaporates, creating varnish after you run it "dry".

Untreated E-10 gas loses a very large percentage of its octane in a very short time--I don't remember the stats, but they're startling. Also, the ethanol tends to attract and combine with water vapor, and then at a particular saturation point and temperature, "dump" the water--it's called "phase separation." Startron and stabilizer in combination (they're two different things) supposedly minimize these issues. If you go through your gas in a couple of weeks, you probably have little to worry about (except marinas with water in their tanks, which is one reason for having a Racor).

Edited by - on

OLarryR
Master Marine Consultant

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USA
3429 Posts

Response Posted - 12/29/2007 : 11:28:44

Well now this issue gets a little bit more confusing with the addl comments and then Leon makes a good case about the environment in which you keep the boat. The thing is that he runs the engine dry and he is in a very humid area. So...then what about the air that is in the carb and the potential for water formation based on the severe humidity conditions. Seems like he has no problems.

I sail in fresh water and at most, maybe do not run the motor for 2 weeks if bad weather , etc keeps me from getting on the boat. Last year was an exception when the Potomac froze over for 1 1/2 months, the year before it did not freeze. So...maybe since I run the motor frequently, probably no reason to run the gas out of the motor...it isn't in there for very long. Maybe water would sometimes condense out of the air if I do run the gas out. No separator or other device needed.

Okay...good day today...I'm outta here goin to go sailing. Weather in the 50s today and then a cold front moves in.

Heading up to Long Beach Island, NJ just north of Atlantic City tomorrow and will be there thru New Years with friends.

Thanks guys for the comments in this thread.

Edited by - on

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