Fuel Water separator question

drod624

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Apr 1, 2015
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2
Hello experts! I'm trying to figure out the right way to change the fuel water separator on my 2000 Mercruiser 4.3. The Seloc manual I have says that I just have to unscrew it, lube the gasket and put it back on. I've heard other things like needing to clamp off the fuel line and having to fill the new filter with clean gas before reinstalling. Would anyone know what the correct method is?

Thank you,
Dennis
 

Bondo

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Apr 17, 2002
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70,465
Hello experts! I'm trying to figure out the right way to change the fuel water separator on my 2000 Mercruiser 4.3. The Seloc manual I have says that I just have to unscrew it, lube the gasket and put it back on. I've heard other things like needing to clamp off the fuel line and having to fill the new filter with clean gas before reinstalling. Would anyone know what the correct method is?

Thank you,
Dennis

Ayuh,.... Welcome Aboard,..... Donno's it's right or wrong, but I'll tell ya how I do it,.....

I crack the ole filter loose with my filter wrench, righty is loosen, as it's upside-down perspective,.....
I slip a qt. size zip-lock freezer baggie 'round it, 'n spin it off, droppin' into the baggie,..... drippage is minimal, no clampin' lines,....
Seal the baggie up, 'n dump the contents of the filter into the baggie, 'n look for water, 'n crud,....

Take the new filter, fill it 'bout 1/2 to 3/4s full, pull the dipstick outa the motor, oil the o-ring with it, 'n screw the new filter on,....
When the gasket/ o-ring contacts, 'bout another 1/4 turn,....

Take care of my tools, toss the old filter, 'n Go Boatin',....

The baggie is a Big help in spillage into the bilge,...
Pre-fillin' the filter, Not full, also helps, less spillage, 'n less work for the fuel pump to prime it again,....
 

drod624

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Apr 1, 2015
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Thank you Bondo!. That zip-lock trick sounds awesome. I didn't even think about the spillage. Much appreciated!
 

stonyloam

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Mar 13, 2009
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5,827
Hey Bondo, do you think you would need to fill the filter on an injected engine? I know on my diesel farm equipment I need to fill the filters before instillation, because it is much more difficult to purge the air from the system. Just wondering if an injected gasoline boat engine would be the same.
 

Bondo

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Apr 17, 2002
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Hey Bondo, do you think you would need to fill the filter on an injected engine? I know on my diesel farm equipment I need to fill the filters before instillation, because it is much more difficult to purge the air from the system. Just wondering if an injected gasoline boat engine would be the same.

Naw, the injectors will self-purge,.... But,....

I have had problems with Efi motors Not reprimin', which is why I started prefillin' all the filters I change,....

The Efi primary fuel pump just wouldn't fill the filter,...
Nothin' to do with the system downstream to the injector, once the filter filled, 'n the pump could Push fuel,...

I live in a Diesel world, I know what runnin' a diesel outa fuel means, Believe me,.... :rolleyes:
Always prefill those filters, except the ole John Deere side mounted glass jobbers,...
 

airshot

Rear Admiral
Joined
Jul 22, 2008
Messages
4,219
I follow Bondo's method with the exception of not prefilling the new filter, my boat has a very long fuel line from tank to engine and if it goes unused for a few weeks it can be hard starting so I added a squeeze ball like those used in outboard motors in my fuel line. A couple squeezes moves the fuel up the line for easier starts and will also fill the new filter after it is installed so I don't spill when replacing it.
 

Outsider

Lieutenant Junior Grade
Joined
Apr 24, 2007
Messages
1,022
I have two canister f/w filters, one on the bulkhead and integral with the fuel pump. I fill each about 3/4, the pump pressurizes fairly quickly when the key comes on, and it's TBI. Losing prime is not an issue, but running dry could be which is why I give the filters a head start ... ;)
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
I added a squeeze ball like those used in outboard motors in my fuel line.
Illegal to have those in a bilge so you never use them on an inboard motor.

I just pre fill the filter.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Just out of curiosity.......how/why is it illegal?
All fuel line in an enclosed area need to be a certain type which is USCG type A1. It has a fire resistant cover. A fuel primer bulb is not certified to be this type. That is why you only see them on outboards and never below deck.

Also the same reason you are not allowed to use those clear plastic inline filters.
 
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